First Aid - Presentations 2

Adhesion (fibrous band of scar tissue, usually after surgery --> most common cause of small bowel obstruction)

Abdominal XR shows multiple dilated small bowel loops

Pulmonary hypertension

Loud P2 (pulmonic component of S2)

Rabies (caused by Rhabdovirus, an enveloped linear negative-sense ssRNA virus with helical capsid that is bullet-shaped --> transmitted via contaminated saliva from bat/raccoon/skunk bite --> penetration of epidermis allows viral glycoprotein-spiked enveloped to attach to nACh receptor of muscles and replicate within muscle cells for several days-weeks --> then spreads RETROGRADE by traveling up peripheral nerve axons until reaching CNS --> causes accumulation of viral ribonuclear proteins within Purkinje cells of cerebellum and pyramidal hippocampal neurons --> presents with initial prodrome of fever/chills/malaise/ paresthesias and then progresses to acute neurologic symptoms such as painful pharyngeal spasms, hydrophobia, hypersalivation, agitation, hyperactivity or ascending paralysis --> brain biopsy shows Negri bodies, aka eosinophilic neuronal cytoplasmic inclusions, within Purkinje cells of cerebellum and pyramidal neurons of hippocampus --> complications: coma and death --> post-exposure prophylaxis includes wound cleaning + Rabies killed vaccine + preformed anti-rabies Ig)

Low-grade fever, headache, malaise, myalgia, difficulty swallowing and painful pharyngeal spasms, muscle spasticity, brain biopsy shows diffuse mononuclear infiltrate and eosinophilic round cytoplasmic inclusions in neurons

Small cell lung carcinoma (SCLC: highly aggressive malignant neoplasm arising from Kulchitsky cells of lung, usually forms from major bronchi in CENTRAL lung --> presents in SMOKERS as hilar mass, SIADH, Cushing syndrome, Lambert-Eaton myasthenia, and/or cerebellar degeneration due to multiple paraneoplastic syndromes --> lung biopsy shows undifferentiated neuroendocrine cells with scant neoplasm and hyperchromatic nuclei --> diagnosis: positive for chromogranin A, synaptophysin, neuron-specific enolase/NSE, and LMYC --> highly aggressive tumor with poor prognosis --> treat with chemotherapy and/or radiation)

Lung biopsy shows flat oval-shaped cells with scant cytoplasm and hyperchromatic nuclei

Lung adenocarcinoma (most common 1° lung cancer, associated with NON-SMOKERS and FEMALE SMOKERS --> presents with solitary "coin lesion" in peripheral lung close to pleura, clubbing and periostosis of small hand bones due to hypertrophic osteoarthropathy, arthralgias, recurrent pleural effusions --> lung biopsy shows well-differentiated glands or papillae with short pump microvilli --> diagnosis: positive for mucin and KRAS/EGFR/ALK mutations --> treat with surgical resection)

Lung biopsy shows invasive cells with abundant cytoplasm and eccentrically placed nuclei that form irregular glandular elements

Lung hamartoma (pulmonary chondroma: excessive growth of a pulmonary tissue native to lung --> usually presents on CXR as solitary lung nodule/coin lesion with "popcorn calcifications" --> biopsy shows disorganized cartilage, fibrous tissue, and adipose tissue)

Lung biopsy shows islands of mature hyaline cartilage, fat, smooth muscle, and clefts lined by respiratory epithelium

Heart failure (lung biopsy shows heart failure cells, aka hemosiderin-laden macrophages/siderophages: occur due to LV dysfunction and impaired forward pumping --> increased pooling of blood within LV, causing increased pulmonary capillary pressure and repeated episodes of pulmonary edema --> increased pressure causes increased permeability of capillary wall and disruption of alveolar-capillary barrier --> extravasation of RBCs into alveoli, causing alveolar hemorrhage --> RBCs phagocytosed by macrophages, and iron from Hb converted to hemosiderin --> iron can be stained with Prussian blue via conversion of colorless K+ ferrocyanide into blue-black ferric ferrocyanide)

Lung biopsy shows macrophages containing golden cytoplasmic granules that turn dark blue with Prussian blue staining

Squamous cell carcinoma of lung (SCC of lung: arises from major bronchi in CENTRAL lung --> presents in MALE SMOKERS as hilar cavitation and hypercalcemia, due to paraneoplastic secretion of PTHrP --> lung biopsy shows well-differentiated epithelial cells with desmosomes and keratinization/keratin pearls --> diagnosis: positive for cytokeratin)

Lung biopsy shows malignant epithelial cells with intercellular bridges and keratin pearls

Fitz-Hugh-Curtis syndrome (perihepatitis: progression of pelvic inflammatory disease to infect liver capsule --> causes inflammation and "violin string" adhesions between liver capsule and peritoneum --> caused by C. trachomatis subacutely or N. gonorrhoeae acutely)

"Violin string" adhesions of peritoneum to liver

Crohn disease (IBD characterized by patchy inflammation that can occur throughout entire GI tract --> present with relapsing/remitting abdominal pain and diarrhea that may or may not be bloody --> typically involves ileum, and inflammation is transmural/segmental in nature --> gross colon will show skip lesions aka sharply delinated ulcerations surrounding normal bowel, cobblestone mucosa, creeping fat, bowel wall thickening, and fissures --> histology will show non-caseating granulomas and lymphoid aggregates --> complications: abscesses, strictures, fistulas)

(+) ASCA (anti-Saccharomyces cerevisiae antibodies)

Multiple sclerosis (autoimmune inflammation/destruction of oligodendrocytes and CNS myelin, mediated by CD4+ T cells activated by myelin basic protein --> associated with HLA-DR2 and usually affecting women in 20s-30s living far away from equator --> results in demyelination of CNS with axonal damage --> presents with acute optic neuritis manifesting as painful unilateral vision loss with Marcus Gunn pupil, brainstem/cerebellar syndromes with intention tremor/scanning speech/ nystagmus/bilateral internuclear ophthalmoplegia, pyramidal tract demyelination with muscle weakness and spasticity, and spinal cord syndromes such as Lhermitte phenomenon/neurogenic bladder/paraparesis/ sensory manifestations --> diagnosis: MRI shows periventricular plaques with "graying" of white matter containing areas of oligodendrocyte loss/reactive gliosis --> treat acute flares with IV steroids, slow progression with IFN-beta therapy)

(+) CD4 T cells activated by myelin basic protein

Hypertrophic pyloric stenosis (congenital gastric outlet obstruction: causes palpable olive-shaped mass in epigastric region due to build up of bolus attempting to enter stomach --> associated with firstborn males and exposure to macrolides during pregnancy --> presents in INFANTS 2-6wks old with palpable epigastric mass, visible peristaltic waves, and non-bilious projectile vomiting --> ultrasound shows thickened and lengthened pylorus --> complication: hypokalemic hypochloremic metabolic alkalosis due to vomiting of gastric acid and subsequent volume contraction --> treat with surgical incision, aka pyloromyotomy)

1-month-old infant with palpable mass in epigastric region, visible peristaltic waves, and non-bilious projectile vomiting

Pulsus paradoxus (inspiration normally causes slight <10mmHg decreased systolic BP/increased HR due to increased venous return to right heart causing a slight bulge of IV septum, thus reducing SV from left heart --> pulsus paradoxus occurs during external compression of ventricles, which constricts left heart during diastolic filling and exaggerates the drop in SV that occurs during inspiration --> in cardiac tamponade and constrictive pericarditis, restricted heart expansion prevents ventricular filling --> in asthma/COPD/ obstructive sleep apnea/croup, upper airway obstruction causes lung hyperinflation during inspiration, which puts pressure on LV and decreases ventricular filling/SV)

>10mmHg drop in systolic BP upon inspiration

Caudate lesion (part of basal ganglia: usually damaged due to lacunar infarcts from uncontrolled HTN or diabetes --> increased stress on endothelium causes leakage of plasma proteins, which causes hyaline thickening of vascular wall, collagenous sclerosis, and accumulation of mural foamy macrophages --> accumulation of foamy macrophages within intimal layer of artery results in microatheromas, which predispose to small vessel occlusion --> usually occludes small penetrating arteries supplying deep brain structures, such as lenticulostriate arteries --> caudate infarct causes symptoms similar to Huntington disease)

Acute onset of agitation, psychosis, abulia, resting tremor, rapid involuntary movements of hand/feet, and slow writhing movements of fingers/toes

AICA infarct (lateral pontine syndrome: caused by obstructed flow in anterior inferior cerebellar artery/AICA, which supplies the LATERAL PONS --> damage to facial nucleus results in ipsilateral facial paralysis with decreased lacrimation/salivation/taste from anterior 2/3 of tongue --> damage to spinal trigeminal nucleus results in ipsilateral loss of pain/temp in face --> damage to vestibular nuclei results in vomiting, vertigo, nystagmus --> damage to labyrinthine artery results in ipsilateral sensorineural deafness and vertigo --> damage to SNS results in Horner's syndrome --> damage to middle/inferior cerebellar peduncles results in ipsilateral ataxia and dysmetria --> and damage to ALS results in loss of pain/temp sensation to CONTRALATERAL body)

Acute onset of ataxia, dysmetria, unilateral loss of lacrimation/salivation/taste, loss of pain/temp sensation of face, deafness and vertigo, loss of pain/temp sensation of trunk/extremities on OTHER side

PICA infarct (lateral medullary syndrome, aka Wallenberg syndrome: caused by obstructed flow in posterior inferior cerebellar artery/PICA, which supplies the LATERAL MEDULLA --> damage to nucleus ambiguus mostly damages vagus nerve/CN10 resulting in dysphagia, hoarseness, loss of gag reflex, hiccups --> damage to vestibular nuclei results in vomiting/vertigo/nystagmus --> damage to ALS and spinal trigeminal nucleus results in loss of pain/temp over IPSILATERAL face and CONTRALATERAL body--> damage to SNS fibers results in Horner's syndrome, aka ptosis/miosis/anhidrosis--> damage to inferior cerebellar peduncle results in IPSILATERAL limb ataxia)

Acute onset of dysphagia, hoarseness, hiccups, loss of gag reflex, unilateral loss of pain/temp sensation in face, loss of pain/temp sensation of body on OTHER side

Lateral prefrontal cortex lesion (usually associated with carotid atherosclerosis or mitral valve emboli --> associated with deficits in attention, and impaired executive function such as planning/organizing, decision making, and purposeful actions)

Acute onset of inability to concentrate, difficulty planning/decision making, re-emergence of primitive reflexes

Anterior spinal artery infarct (medial medullary syndrome: caused by infarct of paramedian branches of ASA and/or vertebral arteries --> damage to lateral CST results in CONTRALATERAL paralysis of upper/lower limbs --> damage to DCML results in CONTRALATERAL loss of touch/vibration sensation in upper/lower limbs --> damage to hypoglossal nerve/CN12 in caudal medulla causes tongue to deviate TOWARD side of lesion)

Acute onset of unilateral paralysis of upper/lower limbs, unilateral loss of touch/vibration sensation in both upper and lower limbs, and tongue deviation

Thalamic stroke (usually damaged due to lacunar infarcts from uncontrolled HTN or diabetes --> increased stress on endothelium causes leakage of plasma proteins, which causes hyaline thickening of vascular wall, collagenous sclerosis, and accumulation of mural foamy macrophages --> accumulation of foamy macrophages within intimal layer of artery results in microatheromas, which predispose to small vessel occlusion --> usually occludes small penetrating arteries supplying deep brain structures, such as lenticulostriate arteries --> damage to VPL nucleus blocks DCML, causing CONTRALATERAL loss of touch/vibration and proprioception, and blocks ALS, causing CONTRALATERAL loss of pain/temp sensation --> damage to VPM causes CONTRALATERAL loss of pain/temp/touch sensation of face)

Acute onset of unsteady gait and complete loss of touch, pain/temp, vibration sense on one side of body

Boerhaave syndrome (esophageal TRANSMURAL tear: increased intragastric pressure during forceful vomiting causes FULL thickness longitudinal lacerations of esophageal wall, associated with ALCOHOLICS and BULIMICS --> caused by severe vomiting, which results in rapid increase in intraabdominal and intraluminal gastric pressure that is transmitted to esophagus via tight LES --> leads to formation of TRANSMURAL tears in distal esophagus that can cause esophageal air/fluid leakage into mediastinum and pleura --> presents with vomiting, chest/upper abdominal pain, and crepitus in neck region or chest wall due to subcutaneous emphysema with dissecting air --> CXR may show pneumomediastinum, aka air in mediastinum --> complications: fever, dyspnea, and septic shock)

Alcoholic patient presents with chest/upper abdominal pain and crepitus in neck region after vomiting, endoscopy shows longitudinal tears in distal eshopagus

Mallory-Weiss syndrome (upper GI MUCOSAL tear: increased intragastric pressure during forceful vomiting causes PARTIAL thickness longitudinal lacerations of GE junction confined to mucosa/submucosa, associated with ALCOHOLICS and BULIMICS --> caused by severe vomiting, which results in rapid increase in intraabdominal and intraluminal gastric pressure that is transmitted to esophagus thru tight LES and leads to formation of mucosal tears in GE junction --> also associated with coughing, hiccuping, repeated abdominal straining during defecation/heavy lifting, and abdominal trauma --> can be asymptomatic or lead to GI hemorrhage with hematemesis --> account for 10% of cases with upper GI bleeding)

Alcoholic patient presents with epigastric pain and hematemesis from vomiting, endoscopy shows longitudinal tears at GE junction

Brugada syndrome (autosomal DOMINANT disorder most common in Asian males --> baseline EKG shows pseudo-RBBB and ST elevations in V1-V3 --> complications: risk of ventricular tacyharrhythmias and sudden cardiac death --> treatment: ICD)

Asian male with baseline EKG showing pseudo-right bundle branch block and ST elevations in V1-V3

Anterior urethral injury (usually associated with PERINEAL STRADDLE INJURY: causes injury to bulbar/spongy urethra --> causes blood to accumulate in scrotum, resulting in scrotal hematoma --> if deep penile/Buck fascia is torn, urine can escape into perineal space --> presents with scrotal hematoma and blood at urethral meatus --> Foley catheter is CONTRAINDICATED because it can worsen injury --> diagnosis: retrograde urethrogram --> NOTE: membranous urethra can be injured in pelvic fractures, while penile urethra can be injured in penetrating trauma or instrumentation)

Avid cyclist presents with scrotal hematoma and blood at urethral meatus

Cauda equina syndrome (compression of spinal roots at and below L2 --> caused by IV disc herniation or tumor --> presents with severe bilateral radicular pain, absent knee/ankle reflexes, saddle anesthesia, and loss of bladder/anal sphincter control --> treat with emergent surgery and steroids)

Back pain that radiates bilaterally down buttocks and posterior thigh, absent knee and ankle reflexes, saddle anesthesia, and loss of bladder and anal sphincter control

C. perfringens, ETEC, V. cholerae (C. perfringens: obligate anaerobic, spore-forming, gram-positive rod whose spores produce heat-labile enterotoxin that cause delayed-onset food poisoning 10-12hrs after ingestion, associated with COOKED food that has been left standing --> ETEC: enterotoxigenic E. coli that is an indole-positive, sorbitol-fermenting, lactose-fermenting gram-negative rod that causes travelers diarrhea, with heat-labile toxin increasing cAMP and Cl- secretion into intestinal lumen, as well as heat-stable toxin increasing cGMP and decreases NaCl absorption intestinal lumen --> V. cholerae: oxidase-positive gram-negative curved rod that grows in alkaline media and is endemic to developing countries, produces cholera toxin that permanently activates Gs to increase Cl- secretion into lumen)

Bacteria that produce enterotoxins within intestine

Diffuse esophageal spasm (spontaneous non-peristaltic contractions of esophagus with normal LES pressure --> presents with episodic dysphagia and angina-like chest pain --> diagnosis: manometry --> treatment: nitrates and Ca2+ channel blockers)

Barium swallow shows "corkscrew" esophagus

Schatzki rings (formation of esophageal rings at GE junction, typically due to chronic acid reflux --> presents with dysphagia)

Barium swallow shows esophageal rings at gastroesophageal (GE) junction

Wolff Parkinson White syndrome (WPW:

Baseline EKG shows delta waves, wide QRS complex, and shortened PR interval

HOCM (hypertrophic obstructive cardiomyopathy)

Bifid carotid pulse with brisk upstroke

Bacillus anthracis (large, non-motile, non-hemolytic, spore-forming gram-positive rod that forms colonies with multiple curled extensions at edges that resemble "Medusa head" --> transmission occurs thru inhalation of spores/inoculation into skin from soil contaminated manure, associated with animal hides/skin and mail workers --> can cause CUTANEOUS anthrax with painless papule surrounded by vesicles that ulcerate and form black escars --> can also cause PULMONARY anthrax in which alveolar macrophages phagocytose spores and bring them to mediastinal lymph nodes, where spores germinate into vegetative rods and multiply --> B. anthracis rods contain D-glutamate polypeptide capsule that is antiphagocytic, and contain exotoxin complex with edema factor, lethal factor, and protective antigen that enters host cells and causes cell death --> presents with hemorrhagic mediastinitis, aka widened mediastinum with shock, brain edema/hemorrhage, and death)

Blood culture shows large, gram-positive rods that form colonies resembling "Medusa head"

Cystic medial degeneration (myxomatous degeneration media of large arteries: associated with Marfan syndrome, in which fibrillin-1 defect causes defective formation of ECM microfibrils and elastic fiber scaffolding --> also associated with beta-aminopropionitrile, a chemical found in certain kinds of sweet peas, that inhibits lysyl oxidase in elastin/collagen cross-linking and can also cause myxomatous degeneration of aorta --> results in fragmentation of elastic tissue with "basket-wave" pattern, formation of small cleft-like spaces filled in amorphous ECM in tunica media, and separation of elastic/fibromuscular components of tunica media --> results in THORACIC aortic aneurysms and aortic dissections)

Blood vessel biopsy shows fragmentation of elastic tissue and pooling of proteglycans in tunica media

Granulomatosis with polyangiitis (small-vessel vasculitis: focal necrotizing vasculitis in nasopharynx, lungs, and kidney --> presents in MIDDLE-AGED MALES with sinusitis, hemoptysis, hematuria --> in URI: causes perforated nasal septum, chronic sinusitis, otitis media, mastoiditis --> in lungs: causes necrotizing granulomas with bilateral nodular densities on CXR, presenting as hemoptysis/cough/dyspnea --> in kidneys: causes RPGN with glomerular crescents on LM and negative IF presenting as hematuria and RBC casts --> diagnosis: C-ANCA, aka anti-proteinase 3 --> treat with cyclophosphamide and prednisone, although relapses are quite common)

Blood vessel biopsy shows large necrotizing granulomas with adjacent necrotizing vasculitis

Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis: small-vessel vasculitis in patients with history of airway allergic hypersensitivity --> presents with asthma, sinusitis, skin nodules/purpura, peripheral neuropathy such as wrist/foot drop, and eosinophilia --> can involve heart, GI, and kidneys causing RPGN with kidney LM showing crescents in Bowman's space and negative IF --> diagnosis: positive P-ANCA/MPO-ANCA, ↑eosinophils, ↑IgE)

Blood vessel biopsy shows large necrotizing granulomas with adjacent necrotizing vasculitis and eosinophilia

Buerger disease (thromboangiitis obliterans: segmental medium-vessel vasculitis due to SMOKING, which causes acute inflammation of arteries and endothelial damage in fingers/toes --> presents in ADULT HEAVY SMOKERS <40y/o with intermittent claudication and small circular deep ulcers on FINGERS and TOES, usually with Raynaud phenomenon ---> arterial biopsy shows segmental thrombosing vasculitis with vein/nerve involvement, often extends into contiguous veins/nerves --> complications: small circular deep ulcers, gangrene, auto-amputation of digits, superficial nodular phlebitis --> treatment: smoking cessation)

Blood vessel biopsy shows segmental thrombosing vasculitis with vein and nerve involvement

Polyarteritis nodosa (PAN: medium-vessel vasculitis that causes necrotizing vasculitis in most organs EXCEPT LUNG: usually seen in middle-aged men and associated with HEPATITIS B in 30% of patients --> often involves renal and mesenteric arteries --> presents with fever, weight loss, malaise, headache, abdominal pain, melena --> biopsy of arterial wall shows transmural inflammation and fibrinoid necrosis --> arteriogram shows innumerable renal microaneurysms and spasms that look like "beads on a string" --> complications: elevated GFR and kidney damage --> treat with corticosteroids and cyclophosphamide)

Blood vessel biopsy shows transmural inflammation with fibrinoid necrosis and alternating dilation/fibrosis

Biotin deficiency (vitamin B7 deficiency: unable to perform carboxylase reactions such as pyruvate carboxylase into oxaloacetate, acetyl CoA carboxylase into malonyl CoA, and propionyl-CoA carboxylase into methylmalonyl-CoA --> causes inability to adequately perform gluconeogenesis, fatty acid synthesis, and fatty acid oxidation --> presents with changes in mental status, myalgia, anorexia, macular dermatitis, enteritis, alopecia, and metabolic acidosis as a result of increase pyruvate entering lactate dehydrogenase pathway)

Bodybuilder who consumes a large amount of raw egg whites presents with myalgia, anorexia, skin rash, macular dermatitis of extremities, hair loss

Paget disease of bone (OSTEOLYTIC PHASE: localized disorder of bone remodeling caused by increased osteoclastic activity, followed by increasing osteoblastic activity that forms poor-quality bone with high risk of fractures --> initial osteolytic phase characterized by abnormally large osteoclasts with >100 nuclei with increased resorption --> mixed phase defined by rapid increase in osteoblast bone formation with persistent osteoclast activity, with interspersed areas of disorganized lamellar/woven bone --> later osteosclerotic phase defined by continued osteoblast bone formation and remodeling that results in dense, hypovascular, mosaic pattern of lamellar bone with irregular haphazardly oriented sections separated by prominent cement lines --> presents with localized bone pain, hearing loss, increasing hat size, recurrent long bone chalk-stick fractures --> lab findings: normal Ca2+/phosphorus/PTH but isolated elevated AlkPhos --> complications: high-output HF from AV shunts and risk of osteosarcoma --> treat with bisphosphonates)

Bone biopsy shows abnormally large osteoclasts with >100 nuclei

Paget disease of bone (OSTEOSCLEROTIC PHASE: localized disorder of bone remodeling caused by increased osteoclastic activity, followed by increasing osteoblastic activity that forms poor-quality bone with high risk of fractures --> initial osteolytic phase characterized by abnormally large osteoclasts with >100 nuclei with increased resorption --> mixed phase defined by rapid increase in osteoblast bone formation with persistent osteoclast activity, with interspersed areas of disorganized lamellar/woven bone --> later osteosclerotic phase defined by continued osteoblast bone formation and remodeling that results in dense, hypovascular, mosaic pattern of lamellar bone with irregular haphazardly oriented sections separated by prominent cement lines --> presents with localized bone pain, hearing loss, increasing hat size, recurrent long bone chalk-stick fractures --> lab findings: normal Ca2+/phosphorus/PTH but isolated elevated AlkPhos --> complications: high-output HF from AV shunts and risk of osteosarcoma --> treat with bisphosphonates)

Bone biopsy shows haphazardly oriented segments of lamellar bone with prominent cement lines

Chondrosarcoma (rare malignant proliferation of chondrocytes --> typically occurs in MEDULLA of pelvis, proximal femur, or proximal humerus --> usually arises de novo, but can sometimes transform from osteochondroma --> bone biopsy shows neoplastic chondrocytes in hyaline cartilage matrix with small calcifications)

Bone biopsy shows neoplastic chondrocytes in hyaline cartilage matrix with small calcifications

Osteosarcoma (malignant proliferation of OSTEOBLASTS that typically occurs in METAPHYSIS of long bones, often in KNEE region --> most common primary bone malignancy, occurs in YOUNG BOYS <20y/o --> can also occur in elderly with Paget disease of bone, bone infarcts, radiation therapy, familial retinoblastoma, and Li-Fraumeni syndrome --> presents as painful enlarging mass or recurrent pathologic fracture of bone --> CXR shows Codman triangle with elevation of periosteum, or sunburst pattern --> aggressive tumor but usually responsible to surgery/chemo)

Bone biopsy shows pleomorphic spindle-shaped cells that produce new osteoid and bone

Ewing sarcoma (primitive undifferentiated tumor that arises from neuroectoderm OR mesechymal stem cells --> 2nd most common childhood bone malignancy after osteosarcoma --> usually occurs in DIAPHYSIS of long bones/femur, pelvic bones, and flat bones --> CXR shows "onion skin" periosteal reaction --> diagnosis: positive for t11:22 translocation and EWS-FL11 fusion protein --> aggressive tumor with early metastases to lungs/other bones, but responds well to chemotherapy)

Bone biopsy shows sheets of small uniform round cells with scant clear cytoplasm, interrupted by vascular fibrous septae, with patches of necrosis and hemorrhage

ITP (immune thrombocytopenic purpura: formation of antibodies against Gp2b/3a from spleen --> causes destruction of platelets by splenic macrophages --> can be idiopathic or associated with SLE, viral illnesses such as HIV/HCV, cancer such as SLL, or drug reactions --> lab findings: ↓platelet count, ↑bleeding time --> bone marrow biopsy shows increased # of megakaryocytes --> treat with steroids, IVIG, rituximab, TPO, or splenectomy to eliminate both SOURCE of auto-antibodies and SITE of destruction)

Bone marrow biopsy shows increased number of megakaryocytes

Hemangioblastoma (adult brain tumor arising from blood vessels, most often occurs in CEREBELLUM --> associated with VHL syndrome when found with retinal angiomas --> can produce EPO and cause paraneoplastic polycythemia --> brain biopsy shows highly vascular architecture with hyperchromatic nuclei)

Brain biopsy shows closely arranged thin-walled capillaries with minimal intervening parenchyma

Schwannoma (adult brain tumor arising from Schwann cells, classically found at CEREBELLOPONTINE ANGLE --> can be along any peripheral nerve, but often involves both CN7 and CN8 --> most commonly presents with CN8 tumor in internal acoustic meatus, causing vestibular schwannoma that presents with unilateral sensorineural hearing loss/tinnitus/vertigo --> BILATERAL schwannomas associated with NF2 --> biopsy shows spindle cells with palisading nuclei arranged around Verocay bodies composed of eosinophilic cores/Antoni A pattern, alternating with hypocellular myxoid stroma/Antoni B pattern --> IHC: positive for S100 --> treat with resection or stereotactic radiosurgery)

Brain biopsy shows dense hypercellular areas containing spindle cells, alternating with hypocellular myxoid areas

Multiple sclerosis (MS: autoimmune disorder that causes inflammation and demyelination of CNS with subsequent axonal damage --> formation of active MS plaques, aka periventricular plaques composed of autoreactive T cells and macrophages against myelin components --> extensive inflammation causes leaky BBB, allowing B cells in perivascular spaces that form myelin-specific antibodies --> causes patchy demyelination and hyertrophy/hyperplasia of astrocytes, aka reactive gliosis --> initially presents in YOUNG ADULT WOMEN with reduced reduced sensation/spasticity in lower extremities, blurry vision, severe fatigue during exercise/hot baths --> eventually damage becomes widespread and can present with diplopia, ataxia, scanning speech, intention tremor, nystagmus/INO, spastic bladder/urge incontinence, parapresis --> screening: CSF shows increased IgG, myelin basic protein, and oligoclonal banding --> diagnosis: MRI shows multiple white matter lesions and periventricular plaques, aka areas with oligodendrocyte loss and reactive gliosis --> treat with IFN-gamma, glatiramer, natalizumab to slow progression of disease --> treat neurogenic bladder with oxybutynin, spasticity with baclofen, and pain with TCA/gabapentin)

Brain biopsy shows focal perivenular inflammatory infiltrates with relative axonal sparing

Glioblastoma (adult brain tumor considered grade IV astrocytoma: highly malignant proliferation of astrocytes found in frontal/temporal/parietal WHITE MATTER --> usually located within cerebral hemispheres and become very LARGE, causing mass effect with MIDLINE SHIFT and may cross corpus callosum causing aka "butterfly glioma" --> gross tumor appears soft with poorly defined areas of necrosis and hemorrhage --> biopsy shows "pseudopalisading" pleomorphic astrocytes bordering central areas of NECROSIS, also associated with abundant neovascular proliferation/hemorrhage --> IHC: positive for GFAP --> highly malignant with ~1yr median survival, can sometimes treat with nitrosureas that cross-link DNA in CNS)

Brain biopsy shows hypercellular areas of atypical astrocytes bordering regions of necrosis

Crutzfeldt-Jakob disease (CJD: prion disease that causes rapidly progressive dementia --> occurs due to conversion of normal alpha-helical prion protein PrP-C to beta-bleated abnormal form PrP-SC, which is resistant to protease degradation AND facilitates conversion of more normal PrP-C to abnormal PrP-SC --> occurs sporadically or infectiously from CNS procedures such as corneal transplants/implantable electrodes/growth hormone prep, as prions are resistant to standard sterilizing procedures such as autoclaving --> presents as RAPIDLY progressive dementia occurring over weeks with myoclonic jerks and ataxia --> EEG: shows periodic sharp waves --> diagnosis: CSF positive for 14-3-3 protein, and brain biopsy shows spongiform encephalopathy with large intracytoplasmic vacuoles within neurons --> no treatment, rapidly fatal)

Brain biopsy shows large intracytoplasmic vacuoles within neurons

Craniopharynioma (childhood brain tumor derived from Rathke's pouch, a remnant of oral ectoderm --> most common childhood SUPRATENTORIAL tumor --> presents in CHILDREN with bitemporal hemianopsia and possible hypopituitarism due to mass effect --> biopsy shows calcifications and cholesterol crystals found in "motor oil-like" fluid within tumor, sometimes called "wet" lamellar keratin)

Brain biopsy shows nests of palisading squamous epithelium with central lamellar keratin

Cavernous hemangioma (BENIGN malformation of blood vessels often involving deeper tissues of body, especially LIVER and BRAIN, and typically occurs in MIDDLE-AGED PATIENTS age 30-50y/o --> grossly appear as a "mullberry-like" mass composed of engorged purplish clusters --> biopsy shows abnormal dilated blood vessels with thin adventitia lacking elastic fibers and smooth muscles --> reduced structural support of blood vessels causes recurrent hemorrhage --> usually asymptomatic, but hemangiomas in brain can cause neurologic defects/seizures due to compression of surrounding tissue and irritation from recurrent bleeding --> also liver biopsy CONTRAINDICATED due to high risk of hemorrhage)

Brain biopsy shows numerous dilated capillaries with an endothelial lining separated by a thin layer of fibrous connective tissue

Ependymoma (brain tumor arising from ependymal cells that surround ventricles: occurs infratentorially around 4th ventricle in CHILDREN, while occurring with spinal central canal in ADULTS --> presents with non-communicating hydrocephalus due to tumor obstructing flow of CSF --> biopsy shows perivascular pseudorosettes, aka tumor cells arranged around blood vessel with thin processes directed toward vessel wall, with rod-shaped blepharoplasts/basal ciliary bodies found near nucleus)

Brain biopsy shows perivascular pseudorosettes and rod-shaped blepharoplasts

Oligodendroglioma (adult brain tumor arising from oligodendrocytes, most often occurs in FRONTAL LOBES --> typically seen in WHITER MATTER of cerebral hemispheres, often CALCIFIED --> gross tumor appears as well-circumscribed gray mass with calcification --> biopsy shows "fried-egg" tumor cells with round nuclei/clear cytoplasm, surrounded by anastomosing capillaries arranged in "chicken-wire" pattern --> CT scan shows solitary calcified mass in frontal lobe --> relatively rare tumor that is slow-growing)

Brain biopsy shows round nuclei surrounded by halo of clear cytoplasm

Red neurons (occurs 12-24hrs after ischemic stroke --> irreversible cell injury to neurons results in nuclear degradation beginning with pyknosis, aka nuclear condensation --> also associated with eosinophilic cytoplasm due to loss of Nissl bodies/RER, which provided the blue staining)

Brain biopsy shows shrunken neurons with intense cytoplasmic eosinophilia and pyknosis of nucleus

Medulloblastoma (most common malignant childhood brain tumor --> arises from primitive neuroectoderm and commonly involves cerebellum near 4th ventricle --> presents in CHILDREN with headaches and papilledema due to non-communicating hydrocephalus from pressure of 4th ventricle --> biopsy shows small cells with hyperchromatic nuclei--primitive neuroectoderm--with Homer-Wright rosettes, aka groupings of cells surrounding the neuropil --> MRI shows SOLID lesion within cerebellum that often causes hydrocephalus --> complication: can send "drop metastases" to spinal cord)

Brain biopsy shows small round blue cells surrounding neuropil

Pilocytic astrocytomas (most common childhood brain tumor: low-grade astrocytoma due to benign proliferation of astrocytes, often found in CEREBELLUM within posterior fossa but may be supratentorial --> presents in CHILDREN with headaches, ataxia, incoordination, other cerebellar findings --> brain biopsy shows well-differentiated bundles of spindle cells with elongated hairlike processes, Rosenthal fibers aka eosinophilic intracytoplasmic inclusions, and granular eosinophilic bodies --> IHC: positive for GFAP --> MRI shows heterogenous, well-circumscribed CYSTIC tumor with mural nodule in cerebellum --> treat with surgical resection, good prognosis)

Brain biopsy shows well-differentiated bundles of spindle cells with hair-like glial processes, eosinophilic intracytoplasmic inclusions, and granular eosinophilic bodies

Meningioma (slow-growing BENIGN adult brain tumor arising from meningothelial cells of arachnoid mater --> form well-circumscribed round mass attached to dura, commonly found within FISSURES/areas of dural reflection, such as parasagittal or lateral convexity regions of brain --> can be asymptomatic, or can compress cerebral cortex and increase ICP --> present in ADULT FEMALES with seizures, headaches, nausea, vomiting that worsens lying down and during sleep --> MRI shows round enhancing lesions within interhemispheric fissures/sulci --> biopsy shows syncytial nests with whorled concentric spindle cell growth and Psammoma bodies, aka round eosinophilic laminar calcified structures --> treat with resection and/or radiosurgery)

Brain biopsy shows whorled concentrically-arranged cells and round laminated calcifications

Bacterial meningitis (inflammation of leptomeninges, aka arachnoid and pia mater: caused by GBS/E coli/Listeria in neonates, H. influenzae in unvaccinated infants, Neisseria gonorrhea in children/teens, S. pneumoniae in adults/elderly, and Listeria in immunocompromised --> presents with fever, headache, nuchal rigidity, photophobia --> diagnose via lumbar puncture at L4/L5 --> complications: brain herniation due to increased ICP, hydrocephalus, hearing loss, seizures due to healing/fibrosis in brain)

CSF findings: non-hemorrhagic neutrophilic pleocytosis, ↑protein, ↑glucose

HSV encephalitis (caused by infection with HSV-1 virus, which is part of herpesvirus family and is enveloped, linear, dsDNA virus --> most common cause of sporadic encephalitis --> presents with acute/subacute changes in mental status, seizures, headaches, focal neurologic deficits --> MRI shows abnormal signal in BILATERAL temporal lobes --> treat with IV acyclovir)

CSF findings: ↑opening pressure, hemorrhagic lymphocytic pleocytosis, ↑protein, normal glucose

Multiple sclerosis (autoimmune inflammation/destruction of oligodendrocytes and CNS myelin, associated with HLA-DR2 and usually affecting women in 20s-30s living far away from equator --> results in demyelination of CNS with axonal damage --> presents with intention tremor, scanning speech, nystagmus, bilateral internuclear ophthalmoplegia --> diagnosis: MRI shows periventricular plaques with "graying" of white matter containing areas of oligodendrocyte loss/reactive gliosis --> treat acute flares with IV steroids, slow progression with IFN-beta therapy)

CSF shows increased IgG, myelin basic protein, and oligoclonal banding

Guillain Barre syndrome (albuminocytologic dissociation: caused by infection with Campylobacter jejuni, an oxidase-positive, comma-shaped gram-negative bacteria with polar flagella that grows in heat/42°C --> transmitted fecal-orally or thru ingestion of undercooked contaminated poultry/meat/milk, also infected animals --> major cause of bloody diarrhea, especially in children --> can lead to molecular mimicry, aka antibodies against C. jejuni also begin attacking GM1 gangliosides in Schwann cells/myelin sheath of peripheral nerves --> myelin sheath stripped from axon at its terminals, leading to loss of neuronal conductivity/ASCENDING axonal degeneration --> presents with lower extremity weakness/paralysis with decreased DTRs with possible autonomic dysregulation or sensory abnormalities --> nerve cell biopsy would show endoneurial inflammation, segmental demyelination, and axon damage)

CSF shows increased protein with normal cell count

Subarachnoid hemorrhage (usually a result of saccular/berry aneurysm rupture associated with ADPKD and Marfan/Ehlers-Danlos --> these connective tissue disorders cause arteries at branch points with turbulent flow occurs at branch points in circle of Willis, usually at anterior communicating artery but can also occur at posterior communicating arteries or MCA --> presents with "thunderclap headache" and nuchal rigidity --> diagnosis: CSF shows blood or yellow xanthrochromia --> sequelae: cerebral vasospasm 3-10 days later causing ischemic infarct, prevent with nimodipine --> complications: communicating or non-communicating hydrocephalus)

CT scan shows hyperattenuation of sulci and basal cisterns

Hypoxic encephalopathy (global cerebral ischemia/GCI or hypoxic stroke: occurs due to GLOBAL interruption of cerebral blood supply due to cardiac arrest, shock, atherosclerotic embolism, anemia, or insulinoma/episodic hypoglycemia --> can be MILD with transient confusion and complete recovery, usually associated with insulinoma --> can be MODERATE with damage to highly vulnerable neurons in layers 3/5/6 of cortex and pyramidal neurons of hippocampus --> can be SEVERE with diffuse liquefactive necrosis of brain and presents with coma/vegetative state/death --> treat with reperfusion, but risk of reperfusion injury due to O2 free radicals)

CT scan shows watershed infarcts at border of perfusion zones

Subdural hematoma (rupture of bridging veins between dura and arachnoid: caused by either high-energy impact trauma or brain atrophy in elderly/alcoholics, and also seen in shaken babies --> presents with progressive neurological deficits --> CT scan may show both acute and chronic hemorrhages --> complication: brain herniation)

CT shows crescent-shaped hemorrhage that crosses suture lines

Epidural hematoma (middle meningeal artery rupture: most commonly caused by injury to pterion region in temporal bone --> collection of blood between dura and skull --> presents with lucid interval before neurologic deficits --> results in rapid intracranial expansion under systemic arterial pressure --> complications: CN3 palsy and transentorial herniation, leading to death)

CT shows lens-shaped hyperdense blood collection that does not cross suture lines

Paget disease of bone (osteitis deformans: localized disorder of bone remodeling seen in ELDERLY --> caused by initial increased osteoclastic activity, followed by increased osteoblastic activity --> results in poor-quality bone that is thick/sclerotic but fractures easily --> presents with bone pain, long bone chalk-stick fractures, increasing hat size, hearing loss, lion-like faces --> osteolytic phase histology shows numerous multinucleated osteoclasts with >100 nuclei, while osteosclerotic phase shows mosaic pattern of lamellar bone with prominent cement lines --> CXR of spine shows "picture frame" vertebrae with cortical thickening of vertebral end-plates --> lab findings: isolated ↑AlkPhos with normal Ca2+, phosphate, PTH --> complications: high-output cardiac failure due to formation of AV shunts and osteosarcoma)

CXR of spine shows vertebral cortical thickening of end-plates, creating "picture frame" vertebrae

Pleural effusion

CXR shows blunting of costophrenic angle

Aortic dissection

CXR shows cardiomegaly, abnormal aortic contour, and widened superior mediastinum

Pulmonary arterial hypertension (PAH: pulmonary blood pressure >25mmHg --> if inherited, due to inactivating mutation in BMPR2 gene causing excess proliferation of vascular smooth muscle --> pulmonary vascular endothelial dysfunction due to increased vasoconstrictors/endothelin + decreased vasodilators such as NO/prostacyclins --> causes thickening of smooth muscle media and hyperplasia of intima in small pulmonary arteries/arterioles --> progressive intimal fibrosis takes place in concentric "onion skin" nature that eventually develops plexiform lesions --> increased vascular resistance in pulmonary arteries leads to increased pulmonary BP --> presents in YOUNG FEMALES with exertional dyspnea --> complications: RV heave due to RVH, loud P2, and cor pulmonale associated with JVD/hepatomegaly/peripheral edema)

CXR shows enlarged pulmonary arteries, enlarged RV, and no pulmonary edema

Emphysema ("pink puffers": imbalance of elastases and anti-elastases in lung causes INCREASED elastase activity --> loss of elastic fibers holding alveolar air sacs together --> breakdown of elastic fibers in interstitium DECREASES the "elastic springs" within interstitium that help open airways, thus DECREASING lung elastic recoil and DECREASING radial traction, resulting in compression of airways and low expiratory flow rates --> loss of elastic fibers also ↑compliance, which allows MORE air to fill alveoli and further compresses the airways/bronchioles --> can be centroacinar in smokers in UPPER LOBES, or panacinar with α1-antitrypsin deficiency in LOWER LOBES --> presents with pink complexion, dyspnea, hyperventilation --> lab findings: ↑FRC, ↑RV, ↑TLC, ↓FEV1/FVC ratio, ↓DLCO)

CXR shows increased AP diameter, flattened diaphragm, and increased lung field lucency

Acute decompensated HF

CXR shows prominent pulmonary vessels, patchy bilateral airspace opacities, and blunting of costophrenic angles

Failure to recanalize (duodenal atresia: failure to recanalize after endothelial proliferation during 8th-10th week of gestation, associated with Down syndrome --> presents in NEWBORNS with bilious vomiting and abdominal distension --> CXR shows "double bubble" sign with dilated stomach and proximal duodenum)

Cause of duodenal atresia

Vascular occlusion (usually of SMA: disruption of mesenteric vessels causes ischemic necrosis of fetal intestinal segment --> causes luminal narrowing/stenosis or obliteration/atresia --> results in PROXIMAL segment ending in a blind pouch, followed by an area of absent small bowel/associated dorsal mesentery, and distal segment assuming spiral configuration around an ileocolic vessel known as "christmas tree" or "apple peel" deformity --> CXR shows dilated loops of small bowel with air-fluid levels)

Cause of jejunal/ileal atresia

Upper trunk compression (damage to musculocutaneous trunk/C5-C7: decreased biceps or triceps reflex, weakness of forearm FLEXION/SUPINATION, loss of sensation over LATERAL forearm)

Cause of musculocutaneous nerve injury

EUS dysfunction (stress incontinence: leakage with increased intra-abdominal pressure such as sneezing, lifting, coughing due to dysfunctional external urethral sphincter --> associated with EUS trauma or pudendal nerve injury during vaginal childbirth, estrogen deficiency/post-menopause, obesity, GU surgery, prostate surgery --> diagnosis: positive bladder stress test, aka directly observing leakage from urethra upon coughing or Valsava maneuver --> treat with pelvic floor muscle strengthening exercises such as Kegels, weight loss, pessaries)

Cause of stress incontinence

Constrictive pericarditis, restrictive cardiomyopathy, RA tumor, or RV tumor

Causes of Kussmaul sign (increased JVP upon inspiration)

Uterine polyp, endometrial hyperplasia, endometrial carcinoma, adenomyosis, leiomyoma, endometriosis (uterine polyp: usually asymptomatic or causes painless AUB --> endometrial hyperplasia: causes non-tender uterus with postmenopausal vaginal bleeding --> endometrial carcinoma: causes non-tender uterus with irregular intermenstrual bleeding --> adenomysosis: causes uniformly enlarged soft globular uterus with AUB, dysmenorrhea, heavy menses --> leiomyoma: causes enlarged uterus with AUB, heavy meses, constipation, urinary frequency, pelvic pain/heaviness --> endometriosis: causes normal-sized uterus with AUB, dysmenorrhea with cyclic pelvic pain, heavy menses, dyspareunia, pain with defection, infertility)

Causes of abnormal menstrual bleeding (AUB)

Fractured surgical neck and anterior dislocation of humerus (damage to axillary nerve/C5-C6 --> causes flattened deltoid, loss of arm abduction at shoulder >15°, and loss of sensation over deltoid/lateral arm)

Causes of axillary nerve injury

Toxoplasma gondii, Neurocysticercosis, CMV, Sturge-Weber syndrome, oligodendroglioma, meningioma, craniopharyngioma (Toxoplasma gondii: CNS protozoa that causes intracranial calcifications in CONGENITAL disease --> neurocysticercosis: caused by tapeworm Taenia solium that causes cystic CNS lesions and seizures --> CMV: causes periventicular calcifications in CONGENITAL disease --> Sturge-Weber syndrome: non-hereditary disorder with GNAQ mutation causing angiomas and hemangiomas in capillary-sized blood vessels --> oligodendroglioma: adult brain tumor most often in frontal lobe --> meningioma: extra-axial adult brain tumor usually found within fissures --> craniopharyngioma: childhood brain tumor derived from Rathke's pouch and found in suprasellar region)

Causes of calcification within the brain

Ischemia, drugs, toxins, fulminant hepatitis (centrilobular region/zone III surrounds terminal hepatic vein and is LEAST oxygenated so highly vulnerable to ischemia --> also contains highest concentration of CYP450 enzymes so most sensitive to metabolic toxins --> ischemia: can be caused by right-sided heart failure or Budd-Chiari syndrome --> drugs: rifampin --> toxins: acetaminophen, CCl4, ethanol, halothane --> fulminant hepatitis: caused by HEV in pregnant women, Vibrio vulnificus in patients with pre-existing liver damage, or halothane injury)

Causes of centrilobular necrosis on liver biopsy

HSV, Mycoplasma, sulfa drugs, penicillin, phenytoin, cancer, SLE (erythema multiforme: cell-mediated immune reaction in which CD8+ T-cells attack antigens deposited within the skin --> NOT a disseminated infection, but rather a systemic immune response to a localized infection --> causes maculopapular rash that evolves into TARGETOID LESIONS with dusky central area, a dark red inflammatory zone surrounded by pale ring, and an erythematous halo in lesion's periphery)

Causes of erythema multiforme

Ethanol, obesity, HCV, Reye syndrome (ethanol: increases NADH/NAD+ ratio in liver, driving conversion of DHAP into glycerol-3-P and acetyl-CoA into fatty acid synthesis, thus increasing TG synthesis and causing macrovesicular fatty change --> obesity: causes fatty infiltration of hepatocytes, resulting in cellular "ballooning" and macrovesicular fatty change --> HCV: mostly associated with periportal necrosis, but also chronic infection causes lymphoid aggregates with focal areas of macrovesicular steatosis --> Reye syndrome: aspirin use in children decreases fatty acid oxidation, causing microvesicular fatty change in liver)

Causes of fatty change in liver (steatosis)

Retinoblastoma, congenital cataracts, toxocariasis

Causes of leukoria (loss of red reflex)

Supracondylar fracture of humerus, carpal tunnel syndrome, and wrist laceration (damage to median nerve/C5-T1 --> causes "ape's hand" and "pope's blessing" --> loss of wrist/lateral finger flexion, loss of thumb opposition, loss of sensation over thenar eminance and dorsal/palmar aspects of first 3 fingers)

Causes of median nerve injury

Detrusor hypotonia or urethral obstruction (overflow incontinence: incomplete emptying causes leakage with overfilling of bladder --> detrusor hypotonia associated with diabetic neuropathy or neurogenic bladder in multiple sclerosis --> urethral obstruction associated with BPH or tumor --> diagnosis: increased post-void residual volume, indicating delayed bladder emptying --> treat with catheterization and relief of obstruction)

Causes of overflow incontinence

Chronic cholestasis, chronic viral hepatitis, A1AT deficiency (periportal region/zone I surrounds portal triad of hepatic artery branches/portal vein branches/bile ductules and is BEST oxygenated but most affected by bloodborne agents and bile duct abnormalities --> chronic cholestasis: due to primary sclerosing cholangitis or primary biliary cholangitis --> chronic viral hepatitis: HBV causes ground-glass hepatocytes while HCV causes abundance of fat/macrovesicular steatosis --> A1AT deficiency: due to buildup of misfolded A1AT protein within hepatocyte ER)

Causes of periportal fibrosis on lung biopsy

Cardiac tamponade, constrictive pericarditis, asthma, obstructive sleep apnea, croup

Causes of pulsus paradoxus

Axilla compression, midshaft fracture of humerus, repetitive screwdriver use (damage to radial nerve/C5-T1 --> cause wrist drop with loss of elbow/wrist/finger extension, loss of grip strength, and loss of sensation over POSTERIOR arm/forearm and dorsal hand)

Causes of radial nerve injury

S. aureus and B. cereus (contain PREFORMED ENTEROTOXIN that is ingested and causes rapid-onset nausea, vomiting, abdominal pain, mild fever, diarrhea with symptoms resolving within a few hours --> Staph aureus: catalase-positive, coagulase-positive, gram-positive cocci in chains that is associated with contaminated meats/mayonnaise/custard, especially if it has been sitting at room temp for extended periods such as picnic/pot luck meals --> Bacillus cereus: spore-forming gram-positive rod whose spores survive in REHEATED RICE and form preformed toxin cerelide, which causes EITHER nausea/vomiting within 1-5hrs OR watery diarrhea/GI pain within 8-18hrs)

Causes of rapid-onset food poisoning (within 1-6hrs)

Medial epicondyle fracture of humerus and fractured hook of hamate (damage to ulnar nerve/C8-T1 --> causes "ulnar claw" with radial deviation of wrist upon flexion, loss of wrist/medial finger flexion, loss of abduction/adduction of fingers due to loss of interossei muscles, and loss of sensation over hypothenar eminance, 1/2 ring finger, and pinky finger)

Causes of ulnar nerve injury

Detrusor hypertonia (overactive bladder: leakage with urge to void immediately --> associated with UTIs,neurogenic bladder in multiple sclerosis, or loss of inhibitory CNS input to bladder due to frontal lobe/internal capsule infarcts causing detrusor hyperreflexia --> treat with Kegel exercises, bladder training, and oxybutynin)

Causes of urge incontinence

Minimal change disease (most common cause of nephrotic syndrome in YOUNG CHILDREN --> can be idiopathic or be caused by inciting event such as respiratory infection/vaccination/inset sting/bite --> results in T cell dysfunction that produces glomerular permeability factor, which damages podocytes and decreases anionic charge of GBM --> loss of negative charge causes selective loss of albumin in urine, causing hypoalbuminemia and edema --> LM shows normal glomeruli --> negative IF --> EM shows diffuse effacement of podocyte foot processes/fusion --> treat with corticosteroids)

Child with an anaphylaxis-causing bee sting 2 weeks ago presents with progressive pitting edema of hands/feet, periorbital edema, mild ascites, and massive proteinuria with frothy urine

Thyroglossal duct cyst (cystic dilation of thyroglossal duct remnant, which connects thyroid to tongue during embryologic development --> located ANTERIOR/MIDLINE and MOVES with swallowing, compared to lateral and fixed persistent cervical sinus)

Child with anterior midline neck mass that moves with swallowing or protrusion of tongue

Kawasaki disease (mucucutaneous lymph node syndrome: medium-vessel vasculitis often seen in ASIAN CHILDREN <4y/o --> characterized by conjunctivitis, desquamating polymorphous rash on palms and soles, cervical lymphadenopathy, strawberry tongue, perioral erythema/fissuring, and hand/foot changes such as edema and periungual desquamation --> often occurs in CORONARY ARTERY, resulting in either coronary artery aneurysm or thrombosis that can manifest as acute MI --> treat with ASPIRIN and IVIG)

Child with cervical lymphadenopathy, desquamating rash on palms and soles, red swollen eyes, bright red tongue

Measles (caused by rubeola virus: part of paramyxovirus family, aka enveloped linear negative-sense ssRNA virus with helical capsid --> transmitted via respiratory droplets, presents in UNVACCINATED children --> contains HA, which mediating cell surface adhesion, and matrix protein, which is involved in viral assembly --> causes initial prodrome of cough/coryza/conjunctivitis and Koplik spots, aka bright red spots with blue-white center on buccal mucosa --> 1-2 days after, development of dark pink confluent maculopapular rash that starts on head/neck and spreads downward --> lymph node biopsy shows Warthin-Finkeldey giant cells in background of paracortical hyperplasia --> complications: subacute sclerosing panencephalitis/SSPE and giant cell pneumonia --> treat with vitamin A supplement)

Child with cough, runny nose, red itchy eyes, and cheek ulcers followed by dark confluent maculopapular rash that starts on face and spreads downward

Chickenpox (caused by VZV/HHV-3: part of herpesvirus family, aka enveloped, linear, dsDNA virus --> transmitted via respiratory secretions or contact with vesicular fluid --> presents in UNVACCINATED children with fever, headache, vesicular rash with erythematous base that starts on trunk and spreads centrifugally to involve face and extremities, lesions seen at DIFFERENT stages of papules/vesicles/pustules/ scabs --> causes initial skin infection, then virus travels via RETROGRADE axonal transport to remain latent in dorsal root/trigeminal ganglia --> can reactivate during times of stress/infection to cause shingles)

Child with fever, headache, vesicular rash with erythematous base that starts on trunk and spreads centrifugally to involve face and extremities

Herpetic gingivostomatitis (caused by HSV-1: herpesvirus, aka enveloped linear dsDNA virus --> causes primary mouth/gingival infection in CHILDREN from 6 months-5yrs --> transmitted via respiratory secretions and saliva --> initially presents as prodrome of fever/chills/malaise --> child later develops painful vesicles extensively covering lips/gingiva that can also spread to palate, tongue, or oropharynx --> vesicles organize into extensive ulcers and resolve within 1-2wks --> screening: Tzanck smear from ulcer base shows multinucleated giant cells and intranuclear eosinophilic Cowdry A inclusion bodies --> diagnosis: PCR of skin lesion --> complication: DEHYDRATION due to pain from gigivostomatitis preventing children eating/drinking anything, also remains latent in trigeminal ganglia and can cause REACTIVATED herpes labialis which is limited to lips, aka cold sores --> treat with acyclovir, or foscarnet/cidofovir if resistant)

Child with fever, irritability, painful ulcers on tongue and gingiva, swollen gums, cervical lymphadenopathy

B-cell ALL (B-cell acute lymphocytic leukemia: unregulated growth and differentiation of B-lymphoblasts in bone marrow --> causes marrow failure with low RBCs, low mature WBCs, and low platelets --> presents in CHILDREN with anemia, recurrent infections, and thrombocytopenia with hemorrhage --> peripheral smear shows increased # of blasts --> IHC: blasts positive for TdT, CD19, CD20, CD21 --> complication: spread to CNS and testes --> BETTER prognosis than T-cell ALL, especially if t12:21 translocation involved --> associated with Down syndrome)

Child with fever, malaise, pallor, petechiae, bleeding, bone pain, and hepatosplenomegaly

Scarlet fever (caused by group A strep/S. pyogenes: catalase-negative, beta-hemolytic, bacitracin-sensitive gram-positive cocci in chains --> contains erythrogenic exotoxin A, which is a superantigen that cross-links TCRs and causes overwhelming immune response --> presents with flushed cheeks, circumoral pallor, strawberry tongue, and blanching sandpaper-like body rash --> treat with penicillin)

Child with fever, sore throat, flushed cheeks, circumoral pallor, bright red tongue, and red sandpaper-like rash on neck/trunk/extremities

Staphylococcal scalded skin syndrome (SSSS: S. aureus infection in newborns/children/adults, usually associated with renal insufficiency --> exfoliative A/B toxin is a protease that cleaves desmoglein in desmosomes, destroying keratinocyte attachments to each other in stratum granulosom --> epidermolysis, aka separation of keratinocytes --> sloughing off of UPPER layers of skin above granulosum, aka positive Nikolsky sign --> preservation of basalis allows healing)

Child with high fever, tachycardia, and large flaccid bullous lesions that are prominent over trunk and abdomen

Hemolytic-uremic syndrome (HUS: caused by Shiga-like toxin from EHEC infection, a lactose-fermenting, indole-positive gram-negative rod that does not ferment sorbitol --> Shiga-like toxin binds to vascular endothelial cells and enhances cytokine release, causing apoptosis and WBC recruitment to endothelium + inactivation of ADAMTS13 --> formation of platelet microthrombi on damaged endothelium results in mechanical hemolysis of RBCs- --> results in platelet consumption, schistocytes, and decreased renal blood flow --> presents in CHILDREN after EHEC infection with triad of thrombocytopenia, MAHA, and acute kidney injury --> peripheral smear shows low platelets and schistocytes --> lab findings: elevated LDH, increased bleeding time, normal PT/PTT --> treat with plasmapheresis, sterodis, rituximab)

Child with history of bloody diarrhea presents with scattered petechial rash,

PDA (patent ductus arteriosus: patent connection between main pulmonary artery and aorta --> associated with continuous "machine-like" murmur --> normally closes after birth with decreased PGE and increased O2 tension, but can also be closed with indomethacin --> if left untreated, can result in differential clubbing and cyanosis--only seen in LOWER extremities--and right-sided HF due to RV hypertrophy)

Child with history of congenital heart disease, exertional dyspnea, fatigue, cyanosis and clubbing of TOES (no finger changes)

Henoch-Schonlein purpura (IgA vasculitis affecting skin and kidneys, often following upper respiratory infection in MALE CHILDREN age 3-11 --> excess IgA/C3 form immune complexes that deposit in small vessels of dermis, GI tract, and kidney mesangium --> classically present with palpable purpuric rash, colicky abdominal pain, polyarthralgia, and IgA nephropathy resulting in episodic hematuria --> kidney LM shows mesangial proliferation, IF shows IgA-based IC deposits in mesangium, and EM shows mesangial IC deposition --> complications: intussusception --> usually self-limiting as immune complexes are cleared, but treat with steroids if severe)

Child with history of recent URI presents with palpable purpura on buttocks/legs, abdominal pain, hematuria and RBC casts

Vesicoureteral reflux (VUR: ureter enters bladder at more PERPENDICULAR angle, causing increased retrograde flow of urine from bladder into ureter --> loss of oblique angle prevents flap-valve mechanism to compress ureter when bladder fills --> presents with chronic pyelonephritis, renal scarring at upper/lower poles of kidneys associated with compound papillae dilation, and secondary HTN)

Child with hypertension, episodic fever and abdominal pain, renal ultrasound shows dilated calyces with overlying cortical atrophy bilaterally at upper and lower poles

Persistent cervical sinus (accounts for 20% all neck masses in children --> occurs due to failure of 2nd pharyngeal cleft obliteration during embryologic development --> remnant of pharyngeal cleft presents as pharyngeal cleft cyst within LATERAL neck anterior to SCM --> does NOT move with swallowing)

Child with lateral neck mass anterior to SCM muscle

Parvovirus B19 (Erythema infectiosum/5th disease: caused by parvovirus B19, aka naked linear ssDNA virus --> transmitted via respiratory droplets and maternal-fetal --> binds to P antigen on RBC precursors, causing erythrocyte destruction --> in CHILDREN, leads to 5th disease/erythema infectiosum/"slapped cheek" disease --> in ADULTS, leads to pure RBC aplasia and arthralgia, as well as aplastic crisis in patients with beta-thalassemia major, hereditary spherocytosis, sickle cell disease --> in FETUS, leads to hydrops fetalis)

Child with red cheeks, followed by maculopapular rash on extremities and trunk

Bloom syndrome (caused by autosomal recessive defect in BLM/RecQL3 gene --> causes defective DNA helicase --> impaired DNA replication and decreased chromosomal stability, leading to increased risk of mutations/cancer --> complications: lymphoproliferative and GI cancers)

Child with short stature, scaly erythematous rashes occurring on sun-exposed areas such as face/arms, scattered telangiectasias

Parinaud sydrome (occurs due to compression of TECTUM in dorsal midbrain --> seen in CHILDREN with pinealoma, YOUNG ADULT FEMALES with multiple sclerosis, and ELDERLY with midbrain stroke or hydrocephalus/dilation of 3rd ventricle --> presents with vertical gaze palsy, pupillary light-near dissociation, lid retraction, and convergence-retraction nystagmus when attempting upward gaze)

Child with sudden onset of headache, eyelid retraction, pupils that react well to near objects but do not react to light, impaired upward gaze, and nystagmus when attempting to look upward

T-cell ALL (T-cell acute lymphocytic leukemia: unregulated growth and differentiation T-lymphoblasts in bone marrow --> often presents in YOUNG BOYS as mediastinal mass causing SVC syndrome with compression of trachea and esophagus --> IHC: blasts positive for TdT, CD2-C8 --> complication: spread to CNS and testes)

Child/teenager with fever, throat pain, dyspnea, tachypnea, inspiratory stridor, worsening dysphagia with solid foods, peripheral smear shows blasts

Ulcerative colitis (IBD associated with autoimmune mucosal/submucosal inflammation with friable mucosa --> inflammation mediated by Th2 --> presents in YOUNG WOMEN with chronic relapsing abdominal pain, bloody diarrhea, and LLQ pain --> often associated with primary sclerosing cholangitis and positive for p-ANCA --> shows pseudopolyps and loss of haustra --> CXR shows "lead pipe" appearance of colon --> histology shows ulcers and crypt abscesses with neutrophils --> complications: toxic megacolon, perforation, colorectal cancer)

Colonoscopy shows "bumps" along distal colon with loss of haustra

Decerebrate posturing (extensor posturing: due to damaged brainstem AT or BELOW level of red nucleus in midbrain, such as midbrain tegmentum or pons --> causes loss of rubrospinal tract, which sends descending excitatory signal to upper limb FLEXORS --> this allows unopposed vestibulospinal tract output, resulting in extensor predominance --> presents in comatose patients with EXTENDED position of arms/legs --> note: has BETTER prognosis than decorticate posturing)

Comatose patient with rigid extension of upper and lower extremities

Decorticate posturing (flexor posturing: due to damaged brainstem ABOVE red nucleus in midbrain, such as cerebral hemispheres or internal capsule --> causes loss of descending INHIBITION from cortex to rubrospinal tract, allowing hyperactivity of upper limb flexors --> presents in comatose patients with FLEXED position of arms that are "close to heart" and EXTENDED legs --> note: has WORSE prognosis than decerebrate posturing)

Comatose patient with rigid flexion of upper extremities and extension of lower extremities

Retinopathy and bronchopulmonary dysplasia (occurs due to TREATMENT with SUPPLEMENTAL O2 --> causes free radical injury in many organs, especially retina and lung --> damages high # of blood vessels in retina, resulting in retinopathy of prematurity and eventual blindness --> O2 enters immature lung, causing excess generation of free radicals that damage lung and impair normal development)

Complications of supplemental O2 treatment in NRDS (neonatal respiratory distress syndrome)

Aortic regurgitation, compression of mediastinum, and thromboembolism (thoracic aortic aneurysm: associated with weak aortic wall due to cystic medial degeneration --> risk factors include HTN, bicuspid aortic valve, Marfan/Ehlers-Danlos syndrome, and 3° syphilis that causes obliterative endarteritis of vasa vasorum --> causes balloon-like dilatation of aortic root, which most often causes aortic regurgitation and increased LV cavity --> also associated with compression of mediastinum and formation of thrombus, which can cause systemic emboli and possible ischemic stroke)

Complications of thoracic aortic aneurysm

Diabetes mellitus, IV drug use, HIV

Conditions associated with psoas abscess

Liposarcoma (soft-tissue malignancies that contain numerous lipoblasts that produce non-membrane-bound cytoplasmic lipid --> causes nuclear indentations and scalloping of nuclear membrane --> present in MIDDLE-AGED ADULTS as slow-growing masses in deep connective tissue spaces of trunk/lower extremities)

Cutaneous mass biopsy shows many round cells with multiple mitoses and clear cytoplasmic vacuoles scalloping the nucleus

Lipoma (BENIGN soft-tissue tumor containing mature adipose tissue)

Cutaneous mass biopsy shows mature fat cells without pleomorphism or scaling

Hypothyroidism (most commonly caused by Hashimoto thyroiditis, but can also be caused by subacute granulomatous thyroiditis, Riedel thyroiditis, iodine deficiency, amiodarone/lithium, Wolff-Chaikoff effect --> low T3/T4 causes decreased BMR, resulting in decreased calorigenesis and cold intolerance/low sweating/weight gain --> decreased CO/blood flow results in dyspnea, dry cool skin, coarse brittle hair, diffuse hair loss, brittle nails --> increased GAGs in interstitial spaces causes high water retention resulting in puffy facies, periorbital edema, and myxedema --> decreased GI motility causes constipation and low appetite --> decreased glycogen/TG use and increased oxidative stress results in proximal muscle weakness, elevated CK, delayed/slow reflexes --> lab findings: high TSH, low T3/T4, hyponatremia due to decreased free water clearance, hypercholesterolemia due to low LDL receptor expression)

Decreased appetite, intermittent constipation, weight gain, enlarged tongue, apathy, slowed speech, forgetfulness, difficulty following complex commands

HOCM (hypertrophic obstructive cardiomyopathy: autosomal dominant disorder due to defect in sarcomeric proteins --> sarcomeres added in parallel, causing asymmetric CONCENTRIC LV hypertrophy near IV septum --> systolic anterior motion of mitral valve pushes against hypertrophic septum, causing obstruction of blood flow thru LV outflow tract/aorta --> obstruction worsens with DECREASED LV volume due to decreased LV filling time and increased LV contractility, usually during exercise --> presents with extertional dyspnea, syncope, faint systolic murmur at left sternal border that INCREASES in intensity with Valsava maneuver/abrupt standing but DECREASES with squatting/hand grip/passive leg raise --> heart biopsy shows myofiber disarray and interstitial fibrosis --> complications: diastolic HF with preserved EF and sudden cardiac death from ventricular arrhythmia --> treatment: stop high-intensity athletics and beta-blockers to increase LV volume and improve CO)

Echocardiogram shows IV septal hypertrophy and increased LV mass

Maxillary nerve lesion (V2 branch of CN5: provides sensation to face between forehead and upper lip --> lesion can be due to trauma, tumors, aneurysms, meningeal infections --> causes loss of sensation on face, loss of corneal reflex, and deviation of mandible TOWARD side of lesion)

Edematous tissue of unilateral eye, mild depression of unilateral zygomatic bone, numbness of skin between left eye and upper lip on one side, diplopia when asked to look upward

Aortic dissection (usually associated with longstanding HTN, which causes medial hypertrophy of aortic vasa vasorum --> causes reduced blood flow to aortic media, resulting in medal degeneration with smooth muscle atrophy --> causes aortic ENLARGEMENT and increased wall stiffness, exacerbating aortic wall stress --> results in TEARING of AORTIC INTIMA, forming of false lumen that fills with blood and bisescts aortic media --> type A dissections involved ascending aorta --> type B dissections involve descending aorta --> dissecting intramural hematoma spreads along aortic wall, compressing major arterial branches and causes BP discrepancy in both arms)

Elderly male with history of hypertension presents with sudden onset of severe chest pain that radiates to back and unequal BP in arms

Aspirin overdose (salicylate overdose: can occur with high anti-inflammatory aspirin doses >3000mg/day, usually seen in ELDERLY --> presents with gastric ulcers, tinnitus, early respiratory alkalosis that later transitions to mixed metabolic acidosis-respiratory alkalosis --> complications: acute kidney injury, chronic interstitial nephritis/analgesic nephropathy, GI bleeding)

Elderly man presents with ringing in ears, nausea, fatigue, mild epigastric tenderness, low PCO2, low HCO3-

Spinal stenosis (abnormal narrowing of spinal canal, usually in lumbar region --> due to degenerative arthritis of spine in ELDERLY, which causes IV disc degeneration and protrusion --> causes loss of disc height, which places disproportionate load on posterior aspect of spinal column, leading to formation of facet joint osteophytes and hypertrophy of ligamentum flavum --> leads to mechanical compression of lumbar nerve roots and results in posture-dependent lower extremity pain, numbness/paresthesia, and weakness that worsens with lumbar EXTENSION--walking upright/standing-- and improves with lumbar FLEXION--walking uphill/leaning)

Elderly man with back and bilateral thigh pain on walking that is relieved by walking uphill/leaning on stroller, episodic tingling in lower extremities

Renal artery stenosis (can occur in ELDERLY due to widespread atherosclerosis or YOUNG WOMEN due to fibromuscular dysplasia --> stenosis causes decreased blood flow thru renal arteries resulting in low GFR, high renin, high Ang II that causes systemic vasoconstriction and treatment-resistant hypertension)

Elderly man with history of MI presents with BP of 200/115 and continuous systolic/diastolic bruit over right posterior flank

SIADH (syndrome of inappropriate antidiuretic hormone secretion: ectopic secretion of ADH --> usually due to small cell lung cancer but also associated with CNS disorders/head trauma and drugs such as carbamazepine, cyclophosphamide, SSRIs --> high ADH causes excessive water RETENTION --> body responds by decreasing aldosterone and increasing ANP/BNP secretion --> results in increased urinary Na+/Cl- excretion to normalize ECF --> euvolemic hyponatremia with continued urinary Na+ excretion --> very low Na+ levels can lead to mental status changes/seizures --> treat with SLOW correction of hyponatremia and ADH antagonists such as coivaptan and tolvaptan --> complication of treatment: central pontine myelinolysis)

Elderly man with history of weight loss presents with recent loss of mental function, mild anemia, low Na+, low Cl-, normal K+, normal BUN and Cr, low plasma osmolality, high urine osmolality

Unilateral renal artery stenosis (most commonly caused by diffuse atherosclerosis with history of CAD, ischemic strokes, peripheral artery disease, smoking, diabetes --> renal artery stenosis due to atheromatous plaque at origin of renal artery --> causes unilateral renal ischemia, which secretes high levels of renin and activates RAAS system causing refractory hypertension --> persistent O2 and nutrient deprivation leads to renal atrophy --> presents with refractory hypertension, recurrent flash pulmonary edema, abdominal bruits, and acute kidney injury after initiation of ACE inhibitor --> kidney biopsy shows crowded glomeruli, tubulointerstitial atrophy/fibrosis, and focal inflammatory infiltrates

Elderly man with refractory hypertension, coronary artery disease, peripheral vascular disease, elevated serum creatinine, ultrasound shows atrophic kidney

Frontotemporal dementia (Pick disease: frontotemporal lobe degeneration --> causes EARLY change in personality/behavior--frontal variant-- or aphasia--temporal variant--but NOT associated with memory loss --> may have some Parkinsonian movement disorders that develop AFTER personality/behavior changes--> histology shows Pick bodies, aka silver-staining round inclusions of hyperphosphorylated tau protein or ubiquinated TDP-43)

Elderly patient that initially presented with personality changes and progressive aphasia but NO memory loss, now presenting with bradykinesia and cogwheel rigidity

Parotitis (acute infection of parotid gland, usually due to S. aureus or mixed oral aerobes/anaerobes --> associated with DECREASED SALIVARY FLOW from dehydration, intubation, anti-cholinergics, salivary calculi, oral cavitary neoplasm, or recent intense teeth cleaning --> presents with ACUTE onset of firm erythematous pre/postauricular swelling that extends to mandible, lockjaw, dysphagia, and systemic symptoms such as fever/chills --> diagnosis: ultrasound/CT shows parotid duct inflammation and/or abscess --> lab findings: elevated serum amylase)

Elderly patient who was recently intubated presents with fever, right jaw pain, firm swelling of preauricular area on right side extending to angle of mandible

Lewy body dementia (SIMULTANEOUS onset of dementia + Parkinsonian symptoms within 1 year --> presents with visual hallucinations, dementia with fluctuating cognition/alertness, REM sleep behavior disorder, and Parkinsonism with resting tremor, cogwheel rigidity, bradykinesia, postural instability, shuffling gait --> brain biopsy shows intracellular eosinophilic inclusions within CORTEX, composed of alpha-synuclein protein)

Elderly patient with 6-month history of visual hallucinations, sleep disturbances, memory loss, bradykinesia, cogwheel rigidity

Aortic sclerosis (benign DYSTROPHIC calcification of aging aortic valve: due to chronic hemodynamic stress or atherosclerotic inflammation --> leads to endothelial/fibroblast necrosis, resulting in release of cell degradation products such as lipofuscin into valvular interstitium --> these promote DYSTROPHIC calcification and thickening of aortic valve leaflets and annulus --> gross aortic valve shows fine gritty white granules/clumps --> biopsy shows sharp-edged, dark purple aggregates that may form Psammoma bodies --> complication: calcific aortic stenosis, causing systolic murmur and outflow obstruction)

Elderly patient with no symptoms or lab findings has heavy calcification of aortic valve

Isolated systolic hypertension (ISH: usually due to AGING, which is associated with endothelial dysfunction + decreased elastin + increased collagen deposition --> causes increased arterial stiffness, especially in AORTA --> decreased compliance of aorta/major peripheral arteries, causing elevated pressure readings during SYSTOLE ONLY --> SBP >140mmHg increases risk of stroke and heart disease --> also associated with severe aortic regurgitation, hyperthyroidism, obstructive sleep apnea due to high SNS tone, anemia)

Elderly patient with periodic headaches, BP of 180/70, and S4 heart sound

HBV (hepatitis B infection: hepadnavirus, aka naked partially dsDNA virus with circular genome and reverse transcriptase --> transmitted parenterally via blood, sexually, and perinatally during birth --> HBV/HCV increase risk of HCC due to increased hepatocyte turnover and generation of local inflammatory cytokines that can result in genetic mutations, but HBV has HIGHER RISK OF HCC due to integration into host genome and production of oncogenic viral proteins --> HBV infects hepatocytes and partially dsDNA is repaired by host cell machinery into covalently closed circular DNA strand --> HBV DNA often inserted into cellular genome by host topoisomerase I, allowing HBV DNA to be present in chromosome of affected hepatocytes and control cell growth/differentiation regions of genome--> also produces HBx viral protein, which serves as a TF that activates cell growth genes and interferes with function of p53)

Elderly patient with progressive fatigue, unintentional weight loss, and massive hepatic lesions with intranuclear fragments of foreign DNA

Actinic keratosis (solar keratosis: precursor lesions to squamous cell carcinoma of skin --> UVA rays from sun penetrate deeper into skin and produces ROS that activate multiple inflammatory cell-surface receptors/nuclear TFs --> leads to DECREASED collagen fibril production with increased metalloproteinase production, which degrade type I/type III collagen and cause SOLAR ELASTOSIS --> around age 30-35, photoaging causes gradual thinning of epidermis with reduction in SQ fat, blood vessels, hair follicles, sweat ducts, sebaceous glands causing skin to become atrophic --> present as small red scaly plaques sun-exposed regions of skin, including FACE, BACK, NECK, EARS with associated wrinkles/coarse texture/purpua/brusing --> skin biopsy shows DYSPLASIA with hyperkeratosis/thickened stratum corneum, parakeratosis/retention of nuclei in stratum corneum, loss of polarity of epidermis layers, and accumulation of ELASTIN within dermis --> risk of squamous cell carcinoma proportional to degree of epithelial dysplasia --> NOTE: multiple actinic keratoses seen in patients with xeroderma pigmentosum --> can treat with topical diclofenac or 5-FU)

Elderly patient with small red scaly plaques on sun-exposed areas of skin (face/back/neck/ears), extensive wrinkling with coarse texture of skin, purpura and ecchymoses, and bleeding from gums

Lichen sclerosis (vulvar atrophy in elderly post-menopausal women causes thinning of epidermis and fibrosis/sclerosis of dermis --> THINNING of skin/erosions with porcelain-white plaques and red/violet border --> benign, but slightly increased risk of non-HPV related vulvar squamous cell carcinoma)

Elderly woman presents with progressive vulvar itching, atrophy of labia minora, and thin parchament-like skin over vulva and anus

Cystocele (ANTERIOR prolapse due to protrusion/hernia of bladder into anterior vaginal wall --> causes enlarged anterior fornix --> associated with loss/weakened muscles and fascial support of pelvis due to child bearing, surgical damage, and/or chronic straining activities related to lifting or constipation)

Elderly woman with bulging of anterior vaginal wall on Valsava maneuver

Gallstone ileus (occurs when a large gallstone >2.5cm erodes the intestinal lumen near the gallbladder and creates a gallbladder-small intestinal fistula --> gallstone then travels down intestine and intermittently obstructs lumen, causing episodic symptoms --> eventually, gallstone may get lodged at ileocecal valve, which has smallest lumen of intestinal tract --> causes MECHANICAL obstruction leading to cessation of intestinal motility, aka gallstone ileus --> presents with crampy abdominal pain, vomiting, bloating, abdominal distension and tenderness, high-pitched "tinkling" bowel sounds --> abdominal XR will show dilated bowel loops with air-fluid levels and pneumobilia, aka air in biliary tree due to retrograde passage of intestinal gas thru fistula)

Elderly woman with episodic abdominal pain, nausea, vomiting, high-pitched bowel sounds, abdominal XR shows air in biliary tree

Polymyalgia rheumatica (INFLAMMATORY chronic disorder characterized by subacute pain/stiffness in shoulders --> usually associated with giant cell/temporal arteritis --> presents in ELDERLY WOMEN with fever, malaise, weight loss, and pain/stiffness in shoulders and pelvic girdle --> lab findings: elevated ESR/CRP with normal CK, indicating inflammatory process OUTSIDE of muscle fibers --> treat with low-dose prednisone)

Elderly woman with fever, malaise, weight loss, muscle pain and stiffness in shoulders/hips

Xerosis (asteatotic dermatitis/winter's itch: defective stratum corneum permeability layer due to indoor heaters lowering the relative humidity of ambient ear --> stratnum corneum permeability affected by loss of extracellular ceramides, fatty acids, sterols that normally provide barrier to prevent excessive transepidermal water loss and hinder skin penetration by irritants --> treat with lower-temp showers and use of emollient moisturizers after bathing)

Elderly woman with pruritic rash with dry cracked skin on bilateral lower extremities

Constrictive pericarditis (chronic inflammation of pericardium due to acute pericarditis, cardiac surgery, radiation therapy, or TB in endemic areas --> causes thick fibrous tissue in pericardial space that forms a non-compliant shell around heart --> prevents ventricular expansion and restricts ventricular filling during diastole, usually on RIGHT SIDE of heart --> results in right-sided heart failure with decreased CO --> presents with fatigue, dyspnea on exertion, hepatomegaly, ascites, peripheral edema, jugular venous distension --> PE findings: elevated JVP, pericardial knock, pulsus paradoxus, and Kussmaul sign)

Elevated JVP, early diastolic sound heard before S3, >10mmHg drop in systolic BP during inspiration, and paradoxical rise in JVP during inspiration

Endometrioid endometrial carcinoma (associated with endometrial hyperplasia pathway, usually due to unopposed estrogen --> risk factors: obesity, diabtes, hypertension, infertility, PCOS --> development of endometrial intraepithelial neoplasia/EIN with nuclear atypia --> presents in MIDDLE-AGED WOMEN with irregular vaginal bleeding --> pathogenesis associated with Lynch syndrome-- aka mutation in mismatch repair--and/or loss of PTEN, a tumor suppressor gene)

Endometrial biopsy shows abnormally arranged endometrial glands

Serous endometrial carcinoma (associated with endometrial atrophy/SPORADIC pathway in post-menopausal women, NO pre-cancerous lesion --> presents in ELDERLY WOMEN with irregular vaginal bleeding --> pathogenesis associated with TP53 mutations --> biopsy shows serous/papillary histology with Psammoma bodies --> highly aggressive, poor prognosis)

Endometrial biopsy shows papillae with fibrovascular cores and laminated concentric calcifications

Diffuse esophageal spasm (spontaneous non-peristaltic contractions of esophagus with normal LES pressure --> presents with episodic dysphagia and angina-like chest pain --> barium swallow shows "corkscrew" esophagus --> diagnosis: esophageal manometry shows intermittent peristalsis and multiple simultaneous contractions from mid and lower esophagus --> treatment: nitrates and Ca2+ channel blockers)

Episodic dysphagia and chest pain, barium swallow shows "corkscrew" esophagus

Reflux esophagitis (chronic inflammation of distal esophagus usually due to GERD --> reflux of gastric acid into distal esophagus causes repeated epithelial injury --> presents with heartburn, regurgitation, dysphagia, chronic cough, hoarseness --> diagnosis: transient decreases in LES tone)

Esophageal biopsy shows elongation of papillae, basal cell hypertrophy, and intraepithelial eosinophils

Barret esophagus (specialized intestinal metaplasia of distal esophagus --> due to chronic GERD)

Esophageal biopsy shows non-ciliated columnar epithelium with goblet cells

Esophageal squamous cell carcinoma (malignant proliferation of squamous cells, usually occurs in upper and middle 2/3 of esophagus --> caused by esophageal irritation: alcohol, smoking, very hot tea, achalasia, esophageal injury, Plummer-Vinson syndrome --> presents with in OLDER MEN >50y/o with solid food dysphagia that progresses to liquid dysphagia, retrosternal discomfort/burning, weight loss, iron-deficiency anemia with fatigue due to chronic GI blood loss --> poor prognosis)

Esophageal biopsy shows solid nests of cells with abundant eosinophilic cytoplasm and distinct borders, areas of keratinization, and presence of intercellular bridges

Sclerodermal esophageal dysmotility (characteristic of BOTH diffuse and limited scleroderma --> occurs due to autoimmune collagen deposition/fibrosis of esophagus, resulting in smooth muscle atrophy --> decreased LES pressure and dysmotility causes GERD and dysphagia --> complications: strictures, Barrett esophagus, and aspiration)

Esophageal mannometry shows decreased peristalsis with decreased LES tone

Aspergillus pneumonia (caused by angioinvasive aspergillosis in immunocompromised patients)

Fever, pleuritic chest pain, hemoptysis, sputum microscopy shows septate hyaline hyphae

Seborrheic keratosis (squamous cell epithelial proliferation of immature keratinocytes with keratin-filled cysts, aka "horn cysts" --> common benign neoplasm of elderly --> present as flat greasy pigmented lesions on head, trunk, extremities that appear "stuck on" --> NOTE: Leser-Trelat sign: rapid onset of multiple seborrheic keratoses, indicating gastric adenocarcinoma)

Flat, greasy, pigmented lesions on head/trunk/extremities that look "stuck on"

Hypertensive retinopathy (retinal damage due to chronic uncontrolled HTN --> initially presents with AV nicking due to endothelial cell necrosis and exudative vascular changes --> eventually progresses to flame-shaped retinal hemorrhages and exudates, aka macular star --> presence of papilledema requires immediate lowering of BP --> associated with higher risk of stroke, CAD, and kidney disease)

Fundoscope exam shows flame-shaped retinal hemorrhages, AV nicking, microaneurysms, macular star, and cotton-wool spots

Retinitis pigmentosa (inherited degeneration of photoreceptors in retina --> first affects rods in peripheral vision, then loss of cones --> presents as painless progressive vision loss beginning with night blindness and loss of peripheral vision --> fundoscopy shows dark clumps of pigment epithelium on retina)

Fundoscopy shows bone spicule-shaped deposits around macula

Central retinal artery occlusion (acute painless monocular vision loss due to occlusion of central retinal artery --> associated with embolism from carotid artery atherosclerosis, cardiac vegetations, patent foramen ovale)

Fundoscopy shows cloudy retina with attenuated vessels and "cherry-red" spot at fovea

Retinal detachment (separation of photoreceptor retinal layer with rods/cones from outermost pigmented epithelium due to retinal breaks, diabetic traction, inflammatory effusions --> degeneration of photoreceptors, resulting in vision loss --> initially presents with posterior vitreous detachment with "flashes" and "floaters," eventually resulting in monocular loss of vision like a "curtain drawn down" --> NOTE: retinal breaks more common in patients with high myopia and/or history of head trauma --> treat with surgery)

Fundoscopy shows crinkling of retinal tissue and changes in vessel direction

Papilledema (bilateral optic disc swelling due to elevated intracranial pressure --> presents with enlarged blind spot)

Fundoscopy shows elevated optic disc with blurred margins

Papilledema (increased intracranial pressure due to venous sinus thrombosis, pseudotumor cerebri, hydrocephalus, Cushing reflex --> increased ICP transmitted thru CSF in subarachnoid space, which is continuous with optic nerve sheath --> buildup of pressure compresses optic nerve externally, resulting in impaired axoplasmic flow within optic nerves causing bilateral optic disc edema/papilledema --> fundoscopy shows enlarged blind spot and elevation of optic disc with blurred margins

Fundoscopy shows elevation of optic disc with blurred disc margins

Open-angle glaucoma (progressive painless bilateral vision loss due to optic disc atrophy --> usually associated with AGING --> can also by blockage of trabecular meshwork and decreased aqueous humor outflow by WBCs due to uveitis, RBCs due to vitreous hemorrhage, or retinal elements due to retinal detachment)

Fundoscopy shows optic disc cupping

GI stromal tumor (GI tumor arising from mesenchyme or muscular cells of submucosa --> usually occurs in stomach, can also be seen in small intestine --> caused by mutation in C-KIT gene that allows constitutively active tyrosine kinase for stem cells, may also be associated with PDGFRA mutation --> grossly appears as a white, fleshy tumor with whorled texture and covered by intact mucosa above --> biopsy shows bundles/fascicles of spindle-shaped mesenchymal cells --> treat with imatinib)

Gastric biopsy shows bundles of spindle cells that are (+)CD117/C-KIT

Chronic H pylori gastritis (caused by H. pylori: curved/spiral-shaped, motile, gram-negative rod that is triple positive for catalase, oxidase, and urease --> colonizes gastric ANTRUM due to urease producing ammonia, which creates alkaline environment to help H. pylori survive in acidic mucosa --> initially causes acute/chronic gastritis, gastric ulcers, and duodenal ulcers --> chronic infection eventually results in gastric mucosal atrophy with patchy destruction of some S cells, G cells, and parietal cells results in LOW gastrin and LOW gastric acid secretion/hypochlorhydria--> presents with gradually worsening heartburn that is either WORSE with meals for gastric ulcers or IMPROVED with meals for duodenal ulcers --> endoscopy shows thickened, nodular mucosa with no discrete ulcerations --> gastric biopsy shows lymphoid aggregates within glands surrounded by acute inflammation of neutrophils/plasma cells --> complications: peptic ulcer disease, gastric adenocarcinoma, and MALT lymphoma --> treat with clarithomycin + amoxicillin + PPI)

Gastric biopsy with Steiner silver (Warthin-Starry silver stain) shows spiral-shaped bacteria that look like "seagulls"

Syphilis (caused by Treponema pallidum: sphirochete that is transmitted sexually --> primary syphilis presents with non-painful indurated genital lesions, aka chancres --> disseminates into skin and lymph nodes to cause secondary syphilis, which presents with widespread maculopapular rash including palms and soles, condylomata lata/wart-like white lesions on genitals, lymphadenopathy, patchy hair loss --> if left untreated, can cause tertiary syphilis with gummas/chronic granulomas usually in LIVER, aortitis with vasa vasorum destruction, neurosyphilis with tabes dorsalis, Argyll Robertson pupil that accommodates but does not constrict with light --> skin biopsy shows obliterative endarteritis with lymphocytes and plasma cells --> screening: dark-field microscopy, VDRL/RPR --> diagnosis: FTA-ABS --> treat with Penicillin G)

Genital skin biopsy shows obliterative endarteritis with lymphocytes and plasma cells

Hyperacute graft rejection (occurs within MINUTES: type 2 HSR mediated by pre-existing recipient antibodies against donor antigen --> activates complement --> complement-mediated hemolysis results in widespread thrombi of graft vessels, causing ischemia and necrosis --> treatment is graft removal)

Graft biopsy shows arterial fibrinoid necrosis and widespread capillary thrombosis/occlusion

Chronic graft rejection (occurs within months to years: BOTH type 2 and type 4 HSR mediated by CD4+ T cells responding to recipient APCs presenting donor peptides, including allogeneic MHC --> activates B cells to class switch and mount mature immune response --> cause graft endothelial damage, obliterative fibrous intimal thickening, and scattered mononuclear infiltration of surrounding tissue --> graft biopsy shows vascular wall thickening/luminal narrowing, interstitial fibrosis, and parenchymal atrophy --> causes bronchiolitis obliterans in lung transplant, accelerated atherosclerosis in heart transplant, chronic graft nephropathy in kidney transplant, and vanishing bile duct syndrome in liver transplant)

Graft biopsy shows proliferation of vascular smooth muscle, parenchymal atrophy, interstitial fibrosis, and vessel arteriolosclerosis

Acute graft rejection (occurs within weeks to months: type 4 HSR mediated by CD8+ T cells and/or CD4+ T cells activated against donor MHCs --> prevent/reverse with immunosuppressants)

Graft biopsy shows vasculitis of graft vessels with dense interstitial lymphocytic cellular infiltrate

Metastatic brain lesions (most often come from lung adenocarcinoma, breast cancer, melanoma, and renal cell carcinoma --> brain biopsy shows central necrosis surrounded by reactive gliosis and edema)

Gross brain shows well-circumscribed masses along grey-white junction

Malignant hypertension (severe hypertension with BP >200/120 that causes hyperplastic arteriolosclerosis of small arteries/arterioles --> results in FIBRINOID NECROSIS of blood vessel wall, causing acute end-organ ischemia --> classically presents with acute renal failure + headache + papilledema due to elevated ICP --> also associated with encephalopathy/stroke, flame-shaped retinal hemorrhages with macular star exudate, acute MI and/or heart failure, aortic dissection, MAHA)

Gross kidney shows "flea-bitten" appearance with pinpoint hemorrhages

Hyaline arteriolosclerosis (occurs due to PROTEIN LEAK from blood vessel lumen into vessel wall, which causes vascular thickening with pink hyaline material within intima --> associated with benign hypertension due to increased hydrostatic pressure driving protein OUT of capillaries into blood vessel wall --> also associated with diabetes mellitus due to non-enzymatic glycosylation of basement membrane, causing a leaky blood vessel wall --> results in REDUCED VESSEL CALIBER that causes gradual end-organ ischemia --> classically produces arteriolonephrosclerosis, aka turbulent blood flow/weakening of AFFERENT arteriole that results in glomerular scarring that progresses to renal failure --> also associated with lacunar infarcts and Charcot-Bouchard aneurysms, which cause strokes in deep brain structures such as internal capsule/basal ganglia)

Gross kidney shows glomerular scarring

Tricuspid endocarditis (associated with IV drug use, usually caused by S. aureus --> tricuspid valve vegetations embolize and get loged in distal portions of pulmonary arterial tree, causing septic pulmonary infarcts that are hemorrhagic and wedge-shaped due to triangular perfusion field of small arteries --> presents with acute onset high-grade fever, profound fatigue, chills, that can quickly progress to septic shock with tachycardia and hypotension)

Gross resected lung shows multiple wedge-shaped red infarcts in periphery of lung

Acute cholecystitis (acute inflammation of gallbladder, usually due to gallstone impaction in cystic duct --> ingestion of fatty foods stimulates I cells in duodenum/jejunum to secrete CKK, which stimulates gallbladder contraction against impacted stone and results in severe colicky RUQ pain --> mechanical disruption of gallbladder mucosa/release of inflammatory mediators causes obstructed gallbladder to become inflamed and edematous, allowing 2° bacterial infection --> presents with fever, tachycardia, vomiting, sudden sharp colicky RUQ pain, cessation of inspiration with deep palpation of RUQ/Murphy sign --> screening: ultrasound showing gallbladder wall thickening and pericholecystic fluid --> DIAGNOSIS: failure to visualize gallbladder on HIDA scan due to obstructed cystic duct --> complications: ascending cholangitis, gallstone ileus, porcelain gallbadder leading to cholangiocarcinoma)

HIDA scan shows failure to visualize gallbladder

Mycobacterium avium (gram-positive acid-fast rod: causes disseminated non-TB disease in AIDS --> prevent phagolysosome formation to evade phagocytosis --> HIV patients have low CD4 count, thus cannot produce IFNy to activate macrophages so M. avium spreads through bloodstream and reticuloendothelial system --> presents with non-specific symptoms such as fever, weight loss, diarrhea, lymphadenitis, anemia, hepatosplenomegaly, elevated AlkPhos, elevated LDH --> bone marrow biopsy shows granulomas with foamy epithelioid histiocytes and Langhans multinucleated giant cells --> culture shows intracellular acid-fast bacteria --> prophylaxis: weekly azithromycin --> treatment: azithromycin or clarithromycin + ethambutol)

HIV patient with CD4 <50 presents with fever, night sweats, weight loss, diarrhea anemia, generalized weakness, generalized lymphadenopathy, hepatosplenomegaly

HOCM (hypertrophic obstructive cardiomyoapthy: predisposes to ventricular arrhythmia and sudden cardiac death)

Heart biopsy shows cardiac myofibrillary disarray and interstitial fibrosis

Acute myocarditis (usually caused by coxsackie B virus, but also associated with adenovirus/influenza --> other less common causes include TB, Chagas disease, and SLE --> mostly asymptomatic, but some patients experience severe complications due to dilated cardiomyopathy --> results in decompensated HF presenting with dyspnea, fatigue, peripheral edema --> biopsy shows massive mononuclear inflammation of cardiomycoytes with widespread necrosis --> complication: sudden cardiac death due to ventricular arrhythmias)

Heart biopsy shows inflammatory mononuclear infiltrate with myofibrillary necrosis

Acute MI

Heart biopsy shows neutrophilic infiltrate, myofiber destruction, and wavy fibers

Cardiac amyloidosis (due to deposition of abnormal proteins in myocardial tissue --> associated with multiple myeloma, autoimmune diseases, familial Mediterranean fever, dialysis patients, familial amyloid cardiomyopathy --> causes RESTRICTIVE cardiomyopathy, resulting in diastolic HF with preserved EF)

Heart biopsy shows pink amorphous material surrounding normal-appearing cardiomyocytes

Alcoholic cerebellar degeneration (long-term heavy alcohol use >10yrs that causes cerebellar degeneration due to chronic nutritional deficiency, such as low thiamine, and direct alcohol-related neurotoxicity --> causes loss of Purkinje cells, especially in cerebellar vermis --> present with progressive wide-based gait ataxia and truncal instability, a coarse rhythmic postural tremor of fingers/hands, diplopia, dysarthria --> PE findings: abnormal tandem gait and heel-to-shin testing)

Homeless man with history of alcoholism presents with frequent falls and "feeling unsteady," blurry vision, and a coarse rhythmic postural tremor affecting fingers and arms

Cushing triad (increased ICP in skull: elevated ICP causes constriction of cerebral arterioles/ischemia --> results in elevated CO2 and low pH --> brain responds with vasoconstriction to increase cerebral perfusion pressure/CPP, also causes compensatory peripheral vasoconstriction, leading to HTN --> baroreceptor reflex responds by causing bradycardia --> compression of brainstem impinges on respiratory regulatory centers and causes difficulty breathing)

Hypertension, bradycardia, respiratory depression

Rubella (German/3-day measles: caused by rubella virus, aka togavirus that is enveloped, linear, positive-sense ssRNA virus with icosahedral capsid --> presents in UNVACCINATED children with fever, postauricular and other lymphadenopathy, and fine maculopapular rash that starts on face and spreads centrifugally to involve trunk and extremities and does NOT coalesce --> presents in ADULTS with fever, polyarthralgia, postauricular lymphadenopathy --> can cause serious CONGENITAL rubella with cataracts, deafness, PDA, and "blueberry muffin" rash)

Immigrant child presents with low-grade fever, generalized fine pink maculopapular rash that started on face and spread rapidly down body, and tender lymphadenopathy bilaterally behind ears

Smallpox (caused by variola virus: part of poxvirus family, aka enveloped, linear, dsDNA virus with dumbbell-shaped core and complex capsid --> replicates in CYTOPLASM because it carries its own DNA-dependent RNA polymerase --> forms Guarnierni bodies/type B inclusion bodies, aka intracytoplasmic inclusion bodies that serve as sites of viral replication --> VERY rarely seen due to vaccines pretty much eradicating smallpox worldwide)

Immigrant child with fever, headache, and raised blisters on skin and mucosal surfaces in mouth/tongue/throat

Abducens nerve palsy (CN6 damage: caused by severe head injury, tumors, cavernous sinus thrombosis, or internal carotid problem --> weak LR muscle in CONTRALATERAL EYE causes loss of abduction --> affected eye displaced medially in primary position of gaze)

Inability to abduct eye, and eye remains deviated toward nose

Kussmaul sign (inspiration usually causes negative intrathoracic pressure and increases venous return to heart, thus DECREASING JVP --> however, a rigid pericardium PREVENTS right side of heart from accommodating increased venous return --> impaired filling of RV causes blood to back up in SVC --> paradoxical rise in JVP during inspiration --> associated with constrictive pericarditis, restrictive cardiomyopathy, RA tumor, or RV tumor)

Increase in JVP on inspiration

Meckel diverticulum

Increased uptake of 99m-Tc-pertechnetate scan in RLQ

Bordatella pertussis (whooping cough: aerobic gram-negative coccobacillus that grows on Bordet-Gengou agar or Regan-Lowe medium --> contains pertussis toxin that disables Gi in respiratory epithelium, causing overactivation AC that increases cAMP and impairs phagocytosis --> also contains tracheal cytotoxin that mediates clinical stages of pertussis: catarrhal with low-grade fevers/coryza, paroxysmal with intense coughs followed by inspiratory whoop and post-tussive vomiting, and convalescent stage with gradual recovery from chronic cough --> prevention: Tdap or DTap vaccines --> treatment: macrolides or TMP-SMX if allergic)

Infant with cough on expiration and "whoops" on inspiration

Congenital torticollis (newborn with SCM injury/fibrosis due to birth trauma/breech delivery OR malposition of head in utero, associated with fetal macrosomia or oligohydramnios --> newborn presents with head tilted TOWARD affected side/chin pointed AWAY from contracted muscle and soft-tissue mass palpable in inferior 1/3 of affected SMC --> may have additional MSK anomalies such as hip dysplasia, adduction of forefoot/metatarsus adductus, and clubfoot/talipes equinovarus)

Infant with head tilted sideways and palpable neck swelling on one side that does not move when swallowing

Roseola (exanthem subitum: caused by HHV-6, an enveloped linear dsDNA virus --> transmitted via saliva --> presents with initial stage of super-high fevers that may cause febrile seizures, followed by TRANSIENT maculopapular rash that appears for a few days on chest and trunk)

Infant with initial few days of very high fever, followed by rose-colored macules on body

Dandy-Walker malformation (developmental absence of cerebellar vermis, resulting in gait unsteadiness and impaired muscle coordination --> leads to cystic dilation of 4th ventricle that fills enlarged posterior fossa, resulting in atresia of foramina of Luschka/Magendie and non-communicating hydrocephalus with elevated ICP --> can also be associated with agenesis of corpus callosum and malformations involving face/heart/limbs --> presents in INFANTS with developmental delay, progressive skull enlargement, cerebellar dysfunction, and elevated ICP causing irritability and vomiting)

Infant with irritability, excessive crying, developmental delay, progressive skull enlargement

Abusive head trauma (AHT, aka "shaken baby syndrome:" caused by blunt force trauma or vigorous shaking of a baby --> infants have larger heads/enlarged subarachnoid spaces/higher brain water content/decreased cervical muscle tone, therefore more susceptible to increased movement of immature brain in relation to skull --> causes tearing of bridging veins and subdural hemorrhages that may appear BOTH acute and chronic on MRI --> presents with BILATERAL RETINAL HEMORRHAGES due to rupture of congested retinal veins, posterior rib fractures, large subdural hemorrhages on MRI)

Infant with lethargy, large full anterior fontanelle, bilateral retinal hemorrhages

Spinal muscular atrophy (autosomal recessive mutation in SMN1 causes congenital degeneration of ventral horns of spinal cord --> results in LMN lesion with symmetric weakness --> presents with "floppy baby" with marked hypotonia/flaccid paralysis and tongue fasciculations)

Infant with marked hypotonia and tongue fasciculations

Patent urachus (due to complete failure of urachus obliteration, resulting in patent connection between umbilicus and bladder --> causes urine to flow form bladder to umbilicus, resulting in clear/straw-colored urine discharge --> INFANT presents with straw-colored urine discharge from umbilicus and local erythema that is exacerbated by crying/straining/prone position --> complication: urachal adenocarcinoma)

Infant with minimal, clear to straw-colored discharge from umbilicus surrounded by erythema and small reducible umbilical hernia

Urachal cyst (failure of CENTRAL part of urachus to obliterate --> results in formation of fluid-filled cavity lined with uroepithelium between umbilicus and bladder --> serves as nidus for infection, and presents in INFANTS with painful mass below umbilicus --> complication: urachal adenocarcinoma)

Infant with painful mass below umbilicus and purulent discharge from umbilicus

Urachal sinus (failure to close DISTAL part of urachus, aka part adjacent to umbilicus --> although urine does not flow from bladder to umbilicus, urachal remnant serves as nidus for infection and causes persistent/recurrent infection --> presents in INFANTS with periumbilical tenderness and purulent umbilical discharge --> complication: urachal adenocarcinoma)

Infant with periumbilical tenderness and purulent discharge from umbilicus

Congenital HIV (due to vertical transmission of HIV from mother to child in utero --> mothers are given triple therapy of 2 NRTIs + protease inhibitor/NNRTI/integrase inhibitor to reduce risk of transmission from 35% to 1% --> then infants receive several weeks of zidovudine as prophylaxis)

Infant with prominent oral thrush, interstitial pneumonia, and severe lymphopenia

Immature LES (immature lower esophageal sphincter --> presents in INFANTS with vomiting and acid reflux)

Infant with vomiting of small amounts, normal weight/height, no other abnormalities

Pityriasis rosea (initial "herald patch" followed days layer by other scaly erythematous plaques often in "Christmas-tree" distribution on trunk --> multiple pink plaques with collarrette scale --> self-resolving in 6-8 weeks)

Initial small erythematous patch on the abdomen, then 1wk later develops patches of pink or red, flaky, oval-shaped plaques spread diffusely over chest following "christmas-tree" distribution

Romano-Ward syndrome (autosomal dominant --> ONLY prolonged QT with no deafness --> complication: development of torsades de pointes and sudden cardiac death)

Isolated long QT on EKG, no associations with drugs/electrolyte abnormalities, no deafness

Malassezia (yeast-like fungus that causes tinea versicolor: malassezia species cause degradation of lipids in the skin --> production of acidic metabolites that inhibit tyrosinase, thus causing hypopigmentation of skin --> can occur anytime, but most often associated with hot humid weather --> KOH prep shows long strings of hyphae with bundles of spores, aka "spaghetti and meatballs" appearance --> treat with selenium sulfide or topical antifungal agents)

KOH prep of skin scraping shows "spaghetti and meatballs" spores with short "cigar-butt" hyphae

Fibrinoid necrosis (occurs due to malignant HTN --> extremely high BP/turbulent blood flow causes vascular necrosis and destruction of arteriolar walls --> results in plasma protein/fibrin leakage from damaged vessel into lumen)

Kidney biopsy shows narrowing of renal arterioles with localized destruction of vascular wall and circumferential ring of pink amorphous material surrounding lumen

Hyperplastic arteriolosclerosis (caused by malignant HTN --> extremely high BP/turbulent flow causes smooth muscle cells to form laminated layers with intervening basement membrane duplication --> results in onion-like concentric SMC thickening of arteriolar walls)

Kidney biopsy shows onion-like concentric thickening of renal arteriolar walls

Analgesic nephropathy (chronic interstitial nephritis due to long-term NSAID use: seen in patients on high-dose NSAIDs for chronic pain, such as patients with back pain who take naproxen daily --> NSAIDs concentrate in renal medulla along medullary osmotic gradient with higher levels in papillae --> uncouple oxidative phosphorylation, causing glutathione depletion and free radical injury --> lipid peroxidation causes fibrosis/atrophy of tubular and vascular endothelial cells --> also decreases PG synthesis in afferent arterioles, causing constriction of medullary vasa recta and ischemic papillary necrosis that can develop calcifications --> presents with mildly elevated creatinine, mild proteinuria and sterile pyuria, evidence of tubular dysfunction such as edema/polyuria/nocturia, and possible distal renal tubular acidosis/type 1 RTA with low H+ secretion/alkaline urine --> renal US shows bilaterally shrunken and irregular kidneys with papillary calcifications --> treat with cessation of NSAID use)

Kidney biopsy shows patchy interstitial inflammation with fibrosis, tubular atrophy, papillary necrosis/scarring with some calcifications, and architectural distortion of calyces

Hyaline arteriolosclerosis (occurs with uncontrolled HTN or diabetes mellitus --> chronic/repetitive endothelial injury caused by hemodynamic stress OR hyperglycemia causes leakage of plasma proteins across vascular endothelium --> stimulates vascular smooth muscle proliferation and excessive ECM production)

Kidney biopsy shows widespread narrowing of renal arterioles with deposition of homogenous, glassy material in subendothelial space that stains pink with PAS stain

Intrinsic renal failure (usually associated with ATN, but can also be caused by acute glomerulonephritis or acute interstitial nephritis --> in ATN, patchy necrosis of renal tubules causes debris to obstruct tubular lumen and cause fluid backflow across necrotic tubule, thus decreasing GFR --> urine shows muddy brown granular casts representing sloughed epithelium --> Na+/H2O/urea reabsorption is IMPAIRED so low BUN/Cr ratio and high fractional excretion of Na+)

Lab findings: Urine osmolality <350 Urine Na+ >40 FE-Na+ >2% Serum BUN/Cr <15

Prerenal azotemia (caused by decreased renal blood flow/RBF during states of hypotension --> decreased GFR causes increased Na+/H2O/urea retained by kidneys to conserve volume --> large BUN/creatinine ration since BUN is reabsorbed but creatinine is not --> also low fractional Na+ excretion due to Na+/H2O reabsorption)

Lab findings: Urine osmolality >500 Urine Na+ <20 FE-Na+ <1% Serum BUN/Cr >20

Isosmotic volume contraction (defined as loss of ISOTONIC fluid, associated with acute GI hemorrhage or diarrhea --> equal loss of BOTH free water and electrolytes results in isolated ECF volume loss with NO EFFECT on plasma osmolarity or ICF volume)

Lab findings: Normal plasma osmolarity ↓ECF volume Normal ICF volume

Hypertonic volume expansion (defined as gain of electrolytes EXCEEDING gain of free water, usually associated with hypertonic saline infusion --> increases BOTH osmolarity and volume of ECF --> pulls water from ICF, which follows high osmolarity --> results in high plasma osmolarity, ECF volume expansion, and ICF volume depletion)

Lab findings: ↑plasma osmolarity ↑ECF volume ↓ICF volume

Hyperosmotic volume contraction (defined as loss of free water EXCEEDING loss of electrolytes due to diabetes inspidus, dehydration/low fluid intake, or profuse sweating due to HYPOTONIC nature of sweat resulting in more fluid loss --> results in increased plasma osmolarity and both ICF/ECF volume depletion)

Lab findings: ↑plasma osmolarity ↓ECF volume ↓ICF volume

Hyposmotic volume expansion (defined as gain in free water EXCEEDING gain in electrolytes, usually due to free water retention from SIADH or excess water consumption/primary polydipsia --> causes free water to flow into cells, thus increasing ICF volume --> also causes decreased plasma osmolarity, which triggers secretion of aldosterone and ANP/BNP to increase electrolyte absorption and stabilize ECF volumes --> results in decreased plasma osmolarity, normal ECF volume, and ICF volume expansion)

Lab findings: ↓plasma osmolarity Normal ECF volume ↑ICF volume

Hyposmotic volume contraction (defined as loss of electrolytes EXCEEDING loss of free water, usually due to adrenal insufficiency/low aldosterone --> causes loss of NaCl from ECF, resulting in low ECF osmolarity --> causes water to move from ECF to higher-osmolarity ICF --> results in low plasma osmolarity, ECF volume depletion, and ICF volume expansion)

Lab findings: ↓plasma osmolarity ↓ECF volume ↑ICF volume

Antiphospholipid syndrome (autoimmune disorder most commonly associated with SLE --> characterized by presence of anti-phospholipid antibodies + hypercoagulable state --> presents with history of DVTs, hepatic vein thrombosis/Budd-Chiari syndrome, recurrent strokes due to cerebral thrombosis, and recurrent pregnancy loss due to placental thrombi --> anti-cardiolipin can cause false positive VDRL/RPR for syphilis screening --> lupus anticoagulant can cause hypercoagulable state with paradoxical prolonged PTT that is not corrected by addition of normal platelet-free plasma --> treatment: lifelong anticoagulation)

Lab findings: (+)anticardiolipin (+)lupus anticoagulant (+)anti-B2-glycoprotein I Prolonged PTTT that does not correct with addition of normal platelet-free plasma

Cyanide poisoning (associated with ingestion of amygdalin/cyanide, excess nitroprusside, synthetic product combustion --> cyanide inhibits Fe3+ in cytochrome c oxidase/complex IV, thus inhibiting oxidative phosphorylation and lowering peripheral tissue O2 CONSUMPTION --> thus no problem with O2 intake, diffusion, or unloading --> presents with hypoxia unresponsive to supplemental O2, increased anaerobic metabolism, CV collapse, ARDS/chemical tracheobronchitis with singed nasal hairs, bitter almond odor of breath --> treat with hydroxocobalamin or nitrite + thiosulfate)

Lab findings: normal PaO2, normal SaO2, normal O2 content, ↑PvO2, ↓arterial-venous O2 gradient

Polycythemia (high Hb concentration: normal SaO2 + high O2 content associated with JAK2 mutation causing primary polycythemia vera OR paraneoplastic EPO production from pheochromocytoma/RCC/ HCC/hemangioblastoma/ leimomyoma --> increased number of Hb allows more O2 to be taken up by RBCs, but ratio remains proportional)

Lab findings: normal PaO2, normal SaO2, ↑O2 content

Anemia (low Hb concentration: associated with iron-deficiency anemia from menstruation or colorectal cancer, thalassemias, sideroblastic anemia, folate/vitamin B12 deficiency, aplastic anemia, or hemolytic anemia --> since there is low Hb but normal oxygenation/diffusion in capillary beds, this manifests as NORMAL PaO2 and NORMAL SaO2 since O2 will fully saturate Hb, but there is just low Hb --> thus causes normal SaO2 with low O2 content)

Lab findings: normal PaO2, normal SaO2, ↓O2 content

CO poisoning

Lab findings: normal PaO2, ↓SaO2, ↓O2 content

Congenital hemophilia (usually hemophilia A: genetic deficiency of factor 8, thus defective intrinsic pathway in coagulation cascade --> unable to make stable platelet-fibrin thrombus --> presents with DEEP tissue bleeding such as hemarthroses, easy bruising, bleeding after trauma/surgery --> diagnosis: increased PTT that corrects after mixing study due to presence of normal factor 8 --> treatment: desmopressin + factor 8 concentrate)

Lab findings: normal platelet count, normal BT, normal PT, ↑PTT that corrects with mixing study

Acquired hemophilia (development of auto-antibodies targeting factors of coagulation cascade, USUALLY against factor 8 --> anti-factor 8 antibodies prevent intrinsic pathway in coagulation cascade, resulting in inability to make stable platelet-fibrin thrombus --> presents with DEEP tissue bleeding such as hemarthroses, easy bruising, bleeding after trauma/surgery --> diagnosis: increased PTT that DOES NOT correct with mixing study due to auto-antibody targeting donor factor 8 as well)

Lab findings: normal platelet count, normal BT, normal PT, ↑PTT that does not correct with mixing study

PSGN (post-strep glomerulonephritis: can occur from previous group A strep impetigo or pharyngitis --> formation of Ag-Ab complexes against M protein, which deposit in glomerular BM --> activation of complement and inflammation leads to nephritic syndrome 2-4wks after infection --> kidney biopsy shows diffusely enlarged hypercellular glomeruli, RBC casts in nephron tubules, and interstitial edema/inflammation --> EM shows dense sub-epithelial deposits/humps along GBM representing Ag-Ab complexes)

Lab findings: urine is (+) for protein/blood, RBC casts ↓serum C3 and C4 ↑serum creatinine (+)anti-DNase B (+)anti-hyaluronic acid (+)ASO (+)anti-NAD

Paget disease of bone (osteitis deformans: localized disorder of bone remodeling seen in ELDERLY --> caused by initial increased osteoclastic activity, followed by increased osteoblastic activity --> results in poor-quality bone that is thick/sclerotic but fractures easily --> presents with bone pain, long bone chalk-stick fractures, increasing hat size, hearing loss, lion-like faces --> osteolytic phase histology shows numerous multinucleated osteoclasts with >100 nuclei, while osteosclerotic phase shows mosaic pattern of lamellar bone with prominent cement lines --> CXR of spine shows "picture frame" vertebrae with cortical thickening of vertebral end-plates --> complications: high-output cardiac failure due to formation of AV shunts and osteosarcoma)

Lab findings: ↑AlkPhos, normal Ca2+, normal phosphate, normal PTH

Chronic bronchitis (hypertrophy and hyperplasia of mucinous glands in bronchi results in increased thickness of mucosal gland layer, associated with SMOKING --> causes "blue bloaters" aka cyanosis, wheezing, crackles, productive cough, elevated PaCO2 --> diagnosis: productive cough for >3 months for >2 consecutive years)

Lab findings: ↑FRC, ↑RV, ↑TLC, ↓FEV1/FVC ratio, Reid index >50%, normal DLCO

Hypoxemia (defect in oxygenation of arteries --> NORMAL A-a gradient: indicates decreased O2 intake from ventilation, thus decreasing PAO2, and includes high altitude or hypoventilation from opioid use/obesity/chronic bronchitis --> INCREASED A-a gradient: indicates problem outside of ventilation and includes V/Q mismatch, diffusion limitation such as fibrosis/emphysema, and right-to-left shunt)

Lab findings: ↓PaO2, ↓SaO2, ↓O2 content

Asthma (REVERSIBLE obstructive lung disease due hyperresponsive bronchi --> type 1 HSR to harmless triggers such as viral URIs, allergens, stress causes reversible bronchoconstriction --> presents with episodic cough, wheezing, tachypnea, dyspnea, hypoxemia mediated by lung hyperinflation, airway mucus plugging, and hypercellular bronchial walls --> diagnosis: Curschmann spirals in sputum and Charcot-Leyden crystals in bronchial secretions --> complication: airway remodeling mediated by eosinophils/helper T cells/mast cells, leading to chronic airway inflammation with smooth muscle hypertrophy --> treat acute attacks with B2-agonists such as albuterol, and daily use of inhaled corticosteroid to prevent airway remodeling)

Lab findings: ↑FRC, ↑RV, ↑TLC, ↓FEV1/FVC ratio, ↓inspiratory/expiratory ratio, normal Reid index, normal DLCO

Emphysema ("pink puffers": imbalance of elastases and anti-elastases in lung causes INCREASED elastase activity --> loss of elastic fibers holding alveolar air sacs together --> breakdown of elastic fibers in interstitium DECREASES the "elastic springs" within interstitium that help open airways, thus DECREASING lung elastic recoil and DECREASING radial traction, resulting in compression of airways and low expiratory flow rates --> loss of elastic fibers also ↑compliance, which allows MORE air to fill alveoli and further compresses the airways/bronchioles --> can be centroacinar in smokers in UPPER LOBES, or panacinar with α1-antitrypsin deficiency in LOWER LOBES --> presents with pink complexion, dyspnea, hyperventilation --> CXR shows increased AP diameter, flattened diaphragm, and increased lung field lucency)

Lab findings: ↑FRC, ↑RV, ↑TLC, ↓FEV1/FVC ratio, ↓lung elastic recoil, ↑compliance, ↓DLCO

Fibrinolysis disorder (overactivation of plasmin causes fibrinogen cleavage: due to radical prostatectomy and increased urokinase release that activates plasmin, OR liver cirrhosis that decreases production of alpha-2 antiplasmin to decrease plasmin inactivation --> presents similar to DIC with increased skin/mucosal bleeding and infarctions BUT has normal platelet counts and normal D-dimers due to lack of microthrombi --> lab findings: normal platelet count, ↑BT, ↑PT, ↑PTT, ↑fibrinogen split products, normal D-dimers --> treat with aminocaproic acid, which blocks activation of plasminogen)

Lab findings: ↑bleeding time, ↑PT, ↑PTT, ↑fibrinogen split products, normal platelet count, normal D-dimers

Cushing disease (ACTH-secreting pituitary adenoma: pituitary tumor of corticotrophs causes increased ACTH secretion, most common cause of endogenous Cushing syndrome --> pituitary is only relatively resistant to feedback inhibition, so a HIGH dose of dexamethasone should suppress both ACTH and cortisol levels --> adrenal CT shows BILATERAL adrenal hyperplasia on adrenal CT due to overactivation of adrenal cortex)

Lab findings: ↑cortisol, no suppression on low-dose dexamethasone, ↑ACTH, adequate suppression on high-dose dexamethasone

Paraneoplastic ACTH secretion (ectopic ACTH secretion from a neoplasm outside of adrenal cortex/pituitary --> usually associated with small cell lung cancer, bronchial carcinoid tumor, and renal cell carcinoma --> since ACTH is being secreted independently from pituitary, high-dose dexamethasone will NOT cause suppression of ACTH/cortisol levels --> adrenal CT shows BILATERAL adrenal hyperplasia due to overactivation of adrenal cortex)

Lab findings: ↑cortisol, no suppression on low-dose dexamethasone, ↑ACTH, no suppression on high-dose dexamethasone

Exogenous glucocorticoid use (excess cortisol intake causes Cushing syndrome with DECREASED ACTH due to negative feedback on pituitary --> low ACTH prevents stimulation of adrenal cortex, causing BILATREAL adrenocortical atrophy --> treat with cessation of GC use)

Lab findings: ↑cortisol, no suppression on low-dose dexamethasone, ↓ACTH, adrenal CT shows bilateral adrenocortical atrophy

Adrenal adenoma (can also be adrenal carcinoma: primary cortisol-secreting tumor in zona fasciculata of adrenal cortex, causing UNILATERAL adrenal hyperplasia --> sends negative feedback to pituitary, decreasing ACTH secretion --> loss of ACTH causes atrophy of NON-AFFECTED adrenal gland --> adrenal CT shows UNILATERAL adrenal hyperplasia with ATROPHY of other adrenal gland)

Lab findings: ↑cortisol, no suppression on low-dose dexamethasone, ↓ACTH, adrenal CT shows unilateral adrenocortical hyperplasia

Central DI (central diabetes insipidus: hypothalamic or posterior pituitary deficiency in ADH secretion --> inability to reabsorb free water in DCT and collecting ducts of kidneys --> excess water excretion and inability to concentrate urine --> presents with polyuria, polydipsia, hypernatremia, low urine osmolality/specific gravity, large increase in urine osmolality after vasopressin test --> lab findings: ↑plasma osmolality, ↓urine osmolality, ↓ADH --> treat with desmopressin/ADH analog)

Lab findings: ↑serum Na+, no change in urine osmolality after water deprivation, LARGE increase in urine osmolality after vasopressin

Nephrogenic DI (nephrogenic diabetes insipidus: impaired renal response to ADH due to ADH receptor mutation, hypercalcemia causing calcification of kidneys, hypokalemia, lithium, or demeclocyline --> inability to reabsorb free water in DCT and collecting ducts of kidneys --> excess water excretion and inability to concentrate urine --> presents with polyuria, polydipsia, hypernatremia, low urine osmolality/specific gravity, mild increase in urine osmolality after vasopressin test --> lab findings: ↑plasma osmolality, ↓urine osmolality, normal ADH --> treat with HCTZ, amiloride, or indomethacin which decreases PG synthesis to increase ADH release)

Lab findings: ↑serum Na+, no change in urine osmolality after water deprivation, mild increase in urine osmolality after vasopressin

SLE (systemic lupus erythematosus: systemic, remitting, relapsing autoimmune disease due to anti-nuclear antibodies/ANA --> circulating antigen-antibody complexes cause type 3 HSR and deposition in skin, joints, serosa, respiratory mucosa, kidneys, and brain --> also causes activation of complement, which further damages tissues and depletes CH50/C3/C4 levels --> classically presents in YOUNG WOMEN with fever, weight loss, fatigue, lymphadenopathy, Raynaud phenomenon, malar or discoid rashes especially on face that are photosensitive, arthritis/joint pain in >2 peripheral joints, painless oral and nasopharyngeal ulcers, serositis such as pleuritis/fibrinous pericarditis, CNS symptoms such as psychosis/seizures, anti-blood cell antibodies that cause type 2 HSR with anemia/low platelets/leukopenia, lupus nephritis with either DPGN or membranous GN, and Libman-Sacks endocarditis with vegetations on BOTH sides of mitral valve --> complications: DPGN which is most common cause of death, recurrent infections, and accelerated CAD --> lab findings: positive for ANA + positive anti-dsDNA or anti-smith or anti-phospholipid antibody such as lupus anticoagulant/anti-cardiolipin/anti-B2-glycoprotein I --> treatment: avoid sun exposure, glucocorticoids for acute flares, immunosuppression for maintenance)

Lab findings: ↓CH50, ↓C3, ↓C4

Pancreatic insufficiency (decreased function of pancreas due to chronic pancreatitis, cystic fibrosis, or obstructing pancreatic adenocarcinoma usually at the head --> causes fat malabsorption and deficiency of fat-soluble vitamins A/D/E/K, as well as deficiency in vitamin B12 --> decreased bicarbonate secretion causes acidic pH in duodenum --> stool findings: fecal elastase and positive Sudan stain for lipids)

Lab findings: ↓duodenal pH, ↑fecal elastase, (+)Sudan stain, normal D-xylose test

DIC (widespread activation of clotting factors due to sepsis, trauma, obstetric complications, acute pancreatitis, adenocarcinoma, APL, nephrotic syndrome, transfusion --> causes formation of microthrombi and excessive consumption of platelets, resulting in increased bleeding with areas of ischemia/infarcts --> microthrombi on endothelial cells induce MAHA, resulting in intravascular hemolytic anemia and schistocytes --> presents with excessive bleeding, especially from IV sites and mucosal surfaces --> peripheral smear shows schistocytes --> lab findings: ↓platelet count, ↑bleeding time, ↑PT, ↑PTT, ↓fibrinogen, ↓factors 5 and8, ↑D-dimers --> treat with platelets/FFP and cryoprecipitate as needed, do NOT give anti-coagulants due to risk of bleeding)

Lab findings: ↓platelet count, ↑bleeding time, ↑PT, ↑PTT, ↓fibrinogen, ↓factors 5 and 8, ↑D-dimers

Primary polydipsia (psychogenic polydipsia: psychological disorder characterized by excess water drinking, most commonly seen in MIDDLE-AGED WOMEN and patients with underlying psychiatric disease --> intact ability to concentrate urine, but increased blood volume due to high fluid intake causes excess water excretion --> presents with polyuria, polydipsia, hyponatremia, low urine osmolality/specific gravity, increase in urine osmolality after water deprivation test --> lab findings: LOW plasma osmolality, ↓urine osmolality, normal ADH --> treat with water restriction to normalize urine output)

Lab findings: ↓serum Na+, increase in urine osmolality after water deprivation, no additional increase in urine osmolality after vasopressin

Knee effusion (accumulation of excess synovial fluid in or around knee joint --> commonly located in SUPRAPATELLAR BURSA, located anteriorly between distal femur/quadriceps and is continuous with synovial cavity of knee itself --> associated with osteoarthritis, rheumatoid arthritis, infection, gout, repetitive strain injury)

Large bulge above the knee, painful passive flexion/extension of knee

Dysplastic nevus syndrome (autosomal dominant disorder caused by CDKN2A gene mutation on chromosome 9 --> encodes cyclin-dependent kinase inhibitor 2A, also known as p16, which binds to and inhibits CDK4 to inhibit cell cycle progression between G1 and GS --> p16 mutations interfere with CD4 inhibition, allowing cell to inappropriately advance in cell cycle --> causes benign but dysplastic nevi/moles throughout body with 75% chance of melanoma in their lifetime --> skin biopsy shows large round/spindle-shaped cells with angulated hyperchromatic nuclei that fuse with adjacent nests at dermoepidermal junction, also form rete pegs/downward thickenings of epidermis between dermal papillae)

Large number of unusual moles found diffusely throughout body

Takayasu arteritis ("pulseless" disease: large-vessel vasculitis --> granulomatous thickening and narrowing of AORTIC ARCH branch points and proximal great vessels such as brachiocephalic, left common carotid, and left subclavian arteries --> presents in YOUNG Asian females <40y/o with fever, night sweats arthritis, myalgias, skin nodules, ocular disturbances, weak upper extremity pulses --> biopsy shows scattered focal granulomatous inflammation of media with intimal thickening, elastic lamina fragmentation, and multinucleated giant cells --> treat with corticosteroids)

Left subclavian artery biopsy shows granulomatous inflammation with multinucleated giant cells, intimal fibrosis, and large separation between intima and media

Gestmann syndrome (damage to angular gyrus of DOMINANT parietal lobe: associated with MCA stroke --> destruction of angular gyrus, which is important for semantic processing/word reading and comprehension/number processing --> presents with left-right disorientation, acalculia, agraphia, finger agnosia --> may also be associated with alexia/inability to read and aphasia/impaired speech)

Left-right disorientation, inability to carry out simple calculations/read/write, inability to identify fingers

Hypovolemic shock (massive loss of blood volume due to acute blood loss, third-spacing with pancreatitis or vasodilation in sepsis, renal problem with excessive diuresis, or GI problem with excessive diarrhea --> low blood volume sensed by JG cells of kidney, which secrete renin to initiate RAAS system and increase aldosterone and increase Na+ absorption/K+ excretion in DCT and CD --> also causes hypothalamus to stimulate thirst and increase ADH secretion, which binds to V1 receptors to cause systemic vasoconstriction and V2 receptors in CD to promote H2O and urea absorption in order to highly concentrate urine --> also causes decreased baroreceptor reflex firing, resulting in INCREASED SNS activity to increase renal NaCl absorption in DCT, CO, and systemic vasoconstriction --> causes rapid increase in BP to help maintain tissue perfusion --> lab findings: BUN/Cr ratio > 20:1 --> urinalysis: super-high urine osmolality, high urine K+, low urine Na+, low FE-Na+)

Lightheadedness, dizziness, lethargy, delayed capillary refill, dry skin with decreased turgor, dry mucus membranes, decreased urine output, hypotension, tachycardia

Sjogren syndrome (autoimmune destruction of exocrine glands: type 4 HSR with lymphocytic destruction of secretory glands, especially lacrimal and salivary glands, due to formation of anti-ribonucleoproteins aka structures composed of RNA and protein --> can be primary or secondary to rheumatoid arthritis or SLE/systemic sclerosis/other autoimmune conditions --> presents in MIDDLE AGED WOMEN between 40-60y/o with inflammatory joint pain, dry eyes with decreased tear production and corneal damage, xerostomia/dry mouth with decreased saliva production, and bilateral parotid gland enlargement --> complications: dental carries in ELDERLY women and MALT lymphoma of parotid gland --> diagnosis: focal lymphocytic sialadenitis on labial salivary gland biopsy which should exclude amyloidosis, sarcoidosis, and drugs/prior radiation --> lab findings: positive for ANA, RF, anti-SSA/Ro, anti-SSB/La)

Lip biopsy shows lymphocytes infiltrating minor salivary glands

HELLP syndrome (hemolysis, elevated liver enzymes, low platelets syndrome: seen in PREGNANT WOMEN as a manifestation of severe eclampsia --> caused by abnormal placental spiral arteries leading to endothelial dysfunction, vasoconstriction, and ischemia --> initially presents as pre-eclampsia with hypertension and proteinuria --> can later present with eclampsia with maternal seizures --> finally presents with HELLP with microangiopathic hemolytic anemia and schistocytes --> complication: DIC and rupture of hepatic subscapular hematoma which cause severe hypotension --> treat with immediate delivery)

Liver biopsy of pregnant woman shows hepatic subscapular hematomas

Alcoholic hepatitis (sustained, long-term consumption of alcohol that causes centrilobular inflammation around central vein --> results in swollen and necrotic hepatocytes with neutrophilic inflammation --> liver biopsy shows hepatocellular swelling/necrosis around central vein, Mallory bodies aka intracytoplasmic inclusions composed of damaged cytokeratin, neutrophilic infiltrate, and fibrosis)

Liver biopsy shows centrilobular swollen and necrotic hepatocytes with eosinophilic cytoplasmic inclusions, neutrophilic infiltrate, and fibrosis

Acute viral hepatitis (infection with hepatitis virus causes significant panlobular lymphocytic inflammation with collapse of reticulin framework, allows "bridging" into adjacent hepatic lobules --> can also see spotty areas of HEPATIC NECROSIS with ballooning pale cytoplasm and/or HEPATIC APOPTOSIS due to cytotoxic T-cell mediated immune response that responds to viral antigens on hepatocyte surface --> apoptotic hepatocytes appear as Councilman bodies, aka round eosinophilic-staining bodies --> NOTE: chronic viral hepatitis has PERIPORTAL inflammation instead of panlobular)

Liver biopsy shows panlobular lymphocytic inflammation with bridging into adjacent lobules, patchy ballooning degeneration hepatocytes, and presence of eosinophilic round bodies scattered amongst parenchyma

Reye syndrome (acute post-infectious disorder seen in CHILDREN given aspirin for viral illnesses --> causes encephalopathy and liver failure)

Liver biopsy shows panlobular microvesicular steatosis

PBC (Primary biliary cirrhosis/cholangitis: chronic autoimmune liver disease that causes destruction of small- and mid-sized intrahepatic bile ducts, resulting in cholestasis --> presents in MIDDLE-AGED WOMEN with autoimmune histories and presents with fatigue, diffuse itching, hepatomegaly, isolated AlkPhos elevation, and positive anti-mitochondrial antibodies --> biopsy shows granulomatous destruction of intrahepatic bile ducts with positive bile staining of hepatocytes --> treat with ursodiol --> NOTE: this biopsy is ALSO SEEN in graft-versus-host disease)

Liver biopsy shows patchy lymphocytic inflammation and granulomatous destruction of intrahepatic bile ducts, with micronodular regeneration of periportal tissues

A1AT (alpha-1 antitrypsin deficiency: mutation associated with PiZ allele causes misfolded A1AT protein that cannot exit hepatocyte and reach lung --> A1AT builds up in hepatocyte ER and causes liver cirrhosis with PAS-positive globules within periportal hepatocytes --> lack of A1AT in lung also allows uninhibited elastase in alveoli to destroy interalveolar septa and cause panacinar emphysema, frequently in LOWER lobes --> presents in YOUNG ADULTS with dyspnea, cough with minimal sputum, prolonged expiration with pursed lips, weight loss, increased AP diameter of chest, mild hepatomegaly, elevated AST and ALT --> lung biopsy shows dilated alveolar air sacs with necrotic alveolar walls --> liver biopsy shows PAS-positive purple globules within periportal hepatocytes --> CXR shows increased AP diameter with flattened diaphragm --> treatment: IV infusion of alpha-1 antitrypsin)

Liver biopsy shows purple-pink globules within periportal hepatocytes

Budd-Chiari syndrome (thrombosis/compression of hepatic vein due to hypercoagulable states, polycythemia vera, postpartum state, hepatocellular necrosis --> results in increased intrahepatic pressure and congestive liver disease --> presents with hepatomegaly, ascites, varices, abdominal pain, liver failure, absence of JVD --> gross liver appears enlarged with tense capsule and reddish-purple parenchyma --> liver biopsy shows centrilobular congestion and necrosis)

Liver biopsy shows severe centrilobular congestion (around central vein) and necrosis

Jervell and Lange-Nielsen syndrome (autosomal recessive --> combo of prolonged QT and sensorineural deafness --> complication: development of torsades de pointes and sudden cardiac death)

Long QT on EKG not associated with drugs/electrolyte abnormalities and sensorineural deafness

Large cell lung carcinoma (LCLC: highly anaplastic undifferentiated tumor, found in lung periphery but closer to hilum than adenocarcinoma --> strongly associated with SMOKING --> lung biopsy shows anaplastic giant cells --> treat is surgical resection, but very poor prognosis due to less responsiveness to chemotherapy)

Lung biopsy shows pleomorphic giant cells

Bronchial carcinoid tumor (malignant lung neoplasm arising from WELL-DIFFERENTIATED neuroendocrine cells --> presents in NON-SMOKERS with polyp-like mass in bronchus, can present with carcinoid syndrome aka flushing/diarrhea/wheezing --> lung biopsy shows sheets/nests of uniform neuroendocrine cells with "salt and pepper" pattern of chromatin --> diagnosis: positive ONLY for chromogranin A --> rarely metastasizes, has excellent prognosis)

Lung biopsy shows sheets of uniform cells with "salt and pepper" pattern

Bronchioloalveolar carcinoma (subtype of lung adenocarcinoma, aka AC in situ: malignant neoplasm arising from Clara cells, usually located at edges of lung near pleura --> associated with NON-SMOKERS and ASBESTOS exposure --> malignant columnar cells grow along alveolar septa, causing apparent "thickening" of alveolar walls --> CXR shows hazy infiltrates, often mistaken for pneumonia --> treat with surgical resection, MUCH better prognosis than other lung cancers)

Lung biopsy shows thickening of alveolar walls with tall columnar cells containing mucus

Bronchiolitis obliterans (type of chronic transplant rejection in lung: CD4+ T cells respond to APCs on donor peptides, activating cytokines and plasma B cells --> causes lymphocytic inflammation and destruction of small airway epithelium --> then forms fibrinopurulent exudate and granulation tissue within lumen of bronchioles --> eventually results in fibrosis, scarring, and progressive obliteration of small airways --> presents in LUNG TRANSPLANT PATIENTS with non-productive cough, dyspnea, decreased FEV1, normal FVC, and decreased FEV1/FVC ratio)

Lung biopsy shows total fibrotic obstruction in terminal bronchioles

Multiple sclerosis (autoimmune inflammation/destruction of oligodendrocytes and CNS myelin, associated with HLA-DR2 and usually affecting women in 20s-30s living far away from equator --> results in demyelination of CNS with axonal damage --> presents with acute optic neuritis with painful unilateral vision loss/Marcus Gunn pupil due to optic nerve injury, brainstem/cerebellar syndromes such as intention tremor/scanning speech/nystagmus/bilateral internuclear ophthalmoplegia, pyramidal tract demyelination causing weakness/spasticity, and spinal cord syndromes such as Lhermitte phenomenon/neurogenic bladder/paraparesis/sensory manifestations affecting trunk or 1+ extremity --> diagnosis: MRI areas of oligodendrocyte loss/ and reactive gliosis --> treat acute flares with IV steroids, slow progression with IFN-beta therapy)

MRI shows periventricular plaques with "graying" of white matter

Meningioma (slow-growing BENIGN adult brain tumor arising from meningothelial cells of arachnoid mater --> form well-circumscribed round mass attached to dura, commonly found in parasagittal or lateral convexity regions of brain --> can be asymptomatic, or can compress cerebral cortex and increase ICP --> present in ADULT FEMALES with seizures, headaches, nausea, vomiting that worsens lying down and during sleep --> biopsy shows syncytial nests with whorled concentric spindle cell growth and Psammoma bodies, aka round eosinophilic laminar calcified structures --> treat with resection and/or radiosurgery)

MRI shows round enhancing lesion within interhemispheric fissure in region of central sulcus

Pilocytic astrocytomas (most common childhood brain tumor: low-grade astrocytoma due to benign proliferation of astrocytes, often found in CEREBELLUM within posterior fossa but may be supratentorial --> presents in CHILDREN with headaches, ataxia, incoordination, other cerebellar findings --> brain biopsy shows well-differentiated bundles of spindle cells with elongated hairlike processes, Rosenthal fibers aka eosinophilic intracytoplasmic inclusions, and granular eosinophilic bodies --> IHC: positive for GFAP --> treat with surgical resection, good prognosis)

MRI shows well-circumscribed cystic lesion with mural nodule

Group B strep, N. gonorrhoeae, Chlamydia, HSV (group B strep: most common cause of neonatal meningitis --> N. gonorrhoeae: causes neonatal conjunctivitis 2-5 days after birth with lid swelling, profuse purulent discharge, possible blindness --> Chlamydia: most common cause of neonatal conjunctivitis, occurs 5-14 days after birth with hyperemia, thick mucopurulent discharge, possible blood --> HSV: causes neonatal conjunctivitis days-6wks after birth with non-purulent discharge, keratitis, vesicular skin lesions, disseminated infection)

Microbes that are transmitted during birth (intrapartum)

Mixed connective tissue disease (autoimmune-mediated tissue damage with mixed features of SLE, systemic sclerosis, and polymyositis --> initially presents with non-specific findings such as fatigue, myalgia, low-grade fever, Raynaud phenomenon --> later develops signs of SLE such as malar/discoid rashes and inflammatory arthritis, signs of sclerosis such as esophageal dysmotility/pulmonary HTN, and signs of polymyositis such as myalgias and proximal muscle weakness with muscle inflammation --> diagnosis: positive ANA and anti-U1 RNP antibodies)

Middle-aged female presenting with malar rash on face and discoid rash on hands, severe arthritis of wrist/hands, esophageal dysmotility, pulmonary hypertension, and proximal muscle weaknesss

TTP (thrombotic thrombocytopenic purpura: inhibition/deficiency of ADAMTS13 typically seen in MIDDLE-AGED FEMALES --> defective ADAMTS13 prevents degradation of vWF multimers --> large vWF multimers INCREASE platelet adhesion and aggregation, causing widespread platelet microthrombi formation and activation in arterioles and capillaries --> microthrombi most commonly affected brain, kidneys, heart --> presents with pentad of thrombocytopenia, MAHA, acute kidney injury, fever, and neurologic symptoms --> peripheral smear shows schistocytes and reduced platelets --> lab findings: elevated LDH, increased bleeding time, normal PT/PTT --> treat with plasmapheresis, steroids, rituximab)

Middle-aged female with fever, abdominal pain, vomiting, lethargy, scattered petechial rash, edema, oliguria, elevated BUN and creatinine, peripheral smear shows schistocytes and reduced platelets

Meningioma (slow-growing BENIGN adult brain tumor arising from meningothelial cells of arachnoid mater, commonly found in parasagittal or lateral convexity regions of brain --> form well-circumscribed round mass EXTERNAL to brain parenchyma, may have dural attachment/tail --> can be asymptomatic, or can compress cerebral cortex and increase ICP --> present in ADULT FEMALES with seizures, headaches, nausea, vomiting that worsens lying down and during sleep --> MRI shows round enhancing lesions within interhemispheric fissures/sulci --> biopsy shows syncytial nests with whorled concentric spindle cell growth and Psammoma bodies, aka round eosinophilic laminar calcified structures --> treat with resection and/or radiosurgery)

Middle-aged female with seizures, headaches, nausea, vomiting that worsens when lying down/during sleep

Diabetic neuropathy (chronic hyperglycemia --> high glucose in Schwann cells --> increased aldose reductase activity --> sorbitol accumulation in Schwann cells, which lack sorbitol dehydrogenase so accumulation of sorbitol --> causes osmotic damage, aka pulls water into cells to cause cellular swelling --> usually associated damage to peripheral motor/sensory nerves, but can ALSO damage autonomic nerves and myenteric nerve plexus in GI tract --> presents with numbness/tingling of extremities often with burning or electric pain, muscle weakness and fasciculations, urinary incontinence, erectile dysfunction and retrograde ejaculation, anorgasmia, difficulty swallowing and DIARRHEA due to myenteric plexus damage)

Middle-aged male with history of T1DM presents with orthostatic hypotension and loose stools

Alkaptonuria (autosomal recessive deficiency of homogentisic acid dioxygenase, which normally metabolizes homogentisic acid into maleylacetoacetate in tyrosine degradation pathway --> causes accumulation of pigmented deposits in connective tissue throughout body, which is ASYMPTOMATIC in childhood but begins to present in ADULTHOOD with severe arthritis, blue-black spots in sclerae and ear cartilage, and black urine when exposed to air)

Middle-aged male with pain in multiple joints, blue-black spots on sclerae, diffuse darkening of auricular helices

Posterior urethral injury (usually associated with PELVIC FRACTURES: causes injury to membranous urethra, aka weakest point due to lack of support from adjacent tissues --> presents with inability to void, sensation of full bladder, blood at urethral meatus, and high-riding boggy prostate due to bloody extravasation and urine leakage into retropubic space --> Foley catheter is CONTRAINDICATED because it can worsen injury --> diagnosis: retrograde urethrogram --> NOTE: bulbous urethra can be injured in straddle injury such as falling on top of a fence, while penile urethra can be injured in penetrating trauma or instrumentation)

Middle-aged male with pelvic fracture presents with inability to void and full bladder sensation

Leukemoid reaction (benign proliferation of MATURE granulocytes, mostly neutrophils: due to INFLAMMATION with infections, medications severe hemorrhage --> can present in any age with focal lymphadenopathy, leukocytosis, ↑LATE neutrophil precursors such as metamyelocytes/band cells, and HIGH leukocyte AlkPhos due to high activity of non-malignant neutrophils --> lab findings: ↑WBCs, ↑LAP, ↑metamyelocytes and band cells, ↓myelocytes, normal basophils and eosinophils --> treat underlying cause of inflammation)

Middle-aged male with sinusitis, tender anterior cervical lymphadenopathy, elevated WBC count, elevated metamyelocytes and band cells, normal basophils/eosinophils, elevated leukocyte AlkPhos

CML (chronic myelogenous leukemia: neoplastic dysregulated proliferation of MATURE and MATURING myeloid cells with predominance of granulocytes --> due to t9:22 translocation, aka Philadelphia chromosome, that results in BCR-ABL fusion protein and constitutive activation of the tyrosine kinase ABL --> usually presents in MIDDLE-AGED/ELDERLY ADULTS between 45-85yrs with splenomegaly, leukocytosis, basophilia, eosinophilia, "myelocytic bulge" with ↑myelocytes compared to metamyelocytes/band cells, and LOW leukocyte AlkPhos due to low activity of malignant neutrophils --> diagnosis: confirmation of t9:22, BCR-ABL fusion gene, or BCR-ABL mRNA --> lab findings: ↑WBCs, ↑eosinophils, ↑basophils, ↓LAP, ↑myelocytes, ↓metamyelocytes and band cells, ↓LAP --> complications: risk of progression to EITHER AML or ALL --> treat with imatinib or dasatinib, aka BCR-ABL tyrosine kinase inhibitors)

Middle-aged male with sinusitis, tender anterior cervical lymphadenopathy, elevated WBC count, elevated myelocytes, elevated eosinophils and basophils, decreased leukocyte AlkPhos

Idiopathic pulmonary fibrosis (type of restrictive lung disease: repeated cycle of lung injury and wound healing --> TGF-B from injured pneumocytes induces collagen deposition within interstitium --> development of pulmonary fibrosis with thickening/stiffening of pulmonary interstitium --> causes INCREASED elastic recoil and airway WIDENING due to increased outward pulling by surrounding fibrotic tissue, aka radial traction --> causes DECREASED airflow resistance, resulting in HIGHER expiratory flow rates --> presents with slowly progressive dyspnea, non-productive cough, and digital clubbing --> CXR shows "honeycomb" appearance of lung with diffuse reticular opacities and decreased lung volume --> lab findings: normal or ↑FEV1/FVC ratio, ↓TLC, ↓FRC, ↓DLCO --> complications: traction bronchiectasis)

Middle-aged man with dyspnea, non-productive cough, bilateral end-inspiratory crackles, drumstick-shaped fingers, CT scan shows diffuse reticular opacities more pronounced at periphery and bases of lungs, and lung biopsy shows patchy interstitial fibrosis/several fibroblastic foci/no granulomas

Legionella (gram-negative rod that gram strains poorly and requires silver stain --> cultured on charcoal yeast extract agar buffered with cysteine and iron --> transmitted via inhaled aerosols from environmental water source habitat such as AC systems/hot water tanks --> presents in SMOKERS or COPD PATIENTS with severe lobar or atypical pneumonia with high fever, GI symptoms, CNS symptoms, HYPONATREMIA --> diagnosis: presence of antigen in urine --> treat with macrolide or quinolone)

Middle-aged man with emphysema presents with sudden onset of headache, myalgia, high fever, dry cough, chills, chest pain, gram stain shows neutrophils and no organisms, highly specialized bacterial medium shows gram-negative rods

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome: autosomal dominant disorder of blood vessels --> presents with blanching lesions/telangiectasias on skin and mucous membranes, recurrent epistaxis, skin discolorations, AV malformations, GI bleeding, and hematuria)

Middle-aged man with history of recurrent nosebleeds presents with progressive shortness of breath with exertion, telangiectasias on mouth and tongue, digital clubbing

Cholelithiasis (gallstone disease: combo of increased fat + estrogen up-regulates HMG Co-A reductase to increase cholesterol synthesis, causing supersaturation of cholesterol in bile --> excess cholesterol in bile causes precipitation of cholesterol into insoluble crystals --> formation of cholesterol gallstone, which are radiolucent with some calcifications --> CCK secretion after fatty meals triggers contraction of gallbladder, forcing stone into cystic duct --> presents with nausea, vomiting, dull RUQ pain that may radiate to right shoulder especially after fatty meals --> complications: calculous cholecystitis, acute pancreatitis, ascending cholangitis)

Middle-aged obese woman presents with abdominal pain after fatty meals, jaundice, tenderness in RUQ

SSPE (Subacute sclerosing panencephalitis: type of SLOW VIRUS infection/complication from childhood measles, which is part of the paramyxofamily with enveloped, linear, negative-sense ssRNA with helical capsid --> usually caused by measles virus with mutated/absent matrix protein, preventing mature enveloped virion particles from forming but allowing virus to continue to replicate intracellularly --> mutated measles virus replication leads to accumulation of viral nucleocapsids within neurons/oligodendrocytes, forming intranuclear inclusions and eventually leading to inflammation, demyelination, and gliosis --> presents with progressive dementia, personality changes, seizures, muscle spasticity, and ataxia --> brain biopsy shows myelin degeneration and viral inclusions --> diagnosis: anti-measles antibodies in CSF and serum, detectable as oligoclonal bands)

Middle-aged patient presents with progressive dementia, personality changes, seizures, muscle spasticity, ataxia, and brain biopsy shows myelin degeneration and viral inclusions

Rosacea (inflammatory facial skin disorder characterized by erythematous papules and pustules, but NO comedones --> may be associated with facial flushing in response to external stimuli such as alcohol, heat, spicy foods --> phymatous rosacea can cause rhinophyma, aka bulbous deformation of nose)

Middle-aged woman with 3-year history of intermittent painful facial erythematous rash on nose/cheeks with scattered telangiectasis and a few papules, gets worse in heat and spicy foods

Trigeminal neuralgia (tic douloreux: irritation of CN5 that follows distribution of trigeminal branches --> symptoms can occur along ophthalmic line, maxillary line, or mandibular line --> episodes are often short, but increase in intensity/frequency over time --> treat with carbamazepine)

Middle-aged woman with episodes of severe lancinating left-sided facial pain that occurs suddenly and lasts 30-60 seconds, shoots from left ear down along jawline, precipitated by chewing or brushing teeth

Acute cholecystitis (acute inflammation of gallbladder, usually due to gallstone obstruction of cystic duct --> preceded by transient episodes of biliary colic, aka abdominal pain/nausea after fatty meals due to CCK causing gallbladder contraction and forcing stone into cystic duct temporarily --> persistent obstruction promotes hydrolysis of luminal lecithins to lysolecithins, disrupting protective mucus layer and exposing gallbladder epithelium to detergent action of bile salts --> chemical irritation/PG release causes inflammation of mucosa and gallbladder hypomotility --> increasing distension/pressure within gallbladder results in ischemia, allowing colonic bacteria such as E. coli/Enterococcus/Klebsiella/Enterobacter to invade necrotic gallbladder wall and cause infection --> presents with fever, persistent RUQ pain, leukocytosis, and positive Murphy sign aka inspiratory pause during deep palpation of RUQ due to pain with pain possibly radiating to right shoulder --> diagnosis: ultrasound showing inflammation and gallbladder wall thickening, OR failure to visualize gallbladder on HIDA scan --> complications: chronic cholecystitis, ascending cholangitis, and porcelain calcified gallbladder with increased risk of cholangiocarcinoma)

Middle-aged woman with history of abdominal pain/nausea after fatty meals presents with fever, persistent RUQ tenderness, nausea, vomiting, elevated WBCs

Fibromyalgia (NON-INFLAMMATORY chronic disorder with widespread MSK pain, fatigue, and neuropsychiatric disturbances known as "fibro fog" --> presents in WOMEN age 20-55 with >3 month history of fatigue, impaired attention and concentration or history of depression/anxiety, poor sleep, diffuse muscle pain with multiple tender points in soft tissues and bony prominences --> lab findings: NORMAL acute phase reactants/other inflammatory markers, indicating absence of muscle/joint inflammation --> treatment: gradual incremental aerobic exercise OR pharmacologic treatment with duloxetine, milnacipran, TCAs, gabapentin)

Middle-aged woman with history of depression presents with shoulder and back pain, easy fatigability, diffuse muscle stiffness that worsens in morning and evening, diffuse soft tissue tenderness

Antiphospholipid syndrome (autoimmune disorder most commonly associated with SLE --> characterized by hypercoaguable state + presence of anti-phospholipid antibodies such as anti-cardiolipin, lupus anticoagulant, and anti-B2-glycoprotein I antibodies --> presents with history of DVTs, hepatic vein thrombosis, recurrent strokes due to cerebral thrombosis, and recurrent pregnancy loss due to placental thrombi --> associated with false VDRL/RPR syphilis screen due to anti-cardiolipin --> also associated lupus anticoagulant can cause hypercoagulable state with paradoxical prolonged PTT that is not corrected by addition of normal platelet-free plasma --> treatment: lifelong anticoagulation)

Middle-aged woman with history of multiple DVTs and strokes, recurrent pregnancy loss, elevated anti-B2-glycoprotein I antibodies

Sclerodermal renal crisis (occurs in women with DIFFUSE scleroderma, aka autoimmune deposition of collagen with fibrosis in various organs/tissues --> due to immune reaction against mesenchymal antigen, which causes dysfunctional endothelial cells --> increased expression of CAMs causes inflammatory cells to invade CT, while increased endothelin release causes vasoconstriction and ischemia leading to end-organ damage --> endothelial cells also secrete PDGF and TGF-beta which activate fibroblasts and cause fibrosis around blood vessels --> DIFFUSE type involves blood vessels causing Raynaud's, GI tract causing delayed emptying of stomach/small bowel malabsorption/esophageal dysmotility, heart causing right-sided HF and cardiac fibrosis, lung involvement with interstitial fibrosis and pulmonary HTN, and kidneys causing sclerodermal renal crisis --> diagnosis: anti-DNA topoisomerase I antibodies and/or anti-Scl-70 antibody --> treat sclerodermal renal crisis with ACE inhibitors)

Middle-aged woman with history of thick tight skin throughout body, GERD and dysphagia with solids and liquids, and Raynaud's phenomenon presents with sudden onset of hypertension and oliguria

Posterior subserosal uterine leiomyoma (uterine fibroids: benign smooth muscle tumors that are ESTROGEN sensitive --> SUBSEROSAL uterine fibroids located on serosal surface of uterus --> cause irregular uterine enlargement that puts pressure on adjacent organs, causing pelvic pressure --> pressure on colon leads to constipation, which patients can relieve by "splinting" to manually defect obstruction --> can also displace uterus UPWARDS and cause obstructive urinary symptoms such as urgency/incomplete emptying --> biopsy shows whorled pattern of smooth muscle bundles with well-demarcated borders --> can treat with leuprolide)

Middle-aged woman with progressively worse pelvic pressure and constipation, irregularly enlarged uterus, and normal rectal tone

Limited scleroderma (autoimmune deposition of collagen with fibrosis in various organs/tissues --> due to immune reaction against mesenchymal antigen, which causes dysfunctional endothelial cells --> increased expression of CAMs causes inflammatory cells to invade CT, while increased endothelin release causes vasoconstriction and ischemia leading to end-organ damage --> endothelial cells also secrete PDGF and TGF-beta which activate fibroblasts and cause fibrosis around blood vessels --> LIMITED scleroderma has limited skin involvement but associated with CREST syndrome: calcinosis cutis aka calcium deposits in skin, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia --> diagnosis: positive anti-centromere antibodies)

Middle-aged woman with thick tight skin over face and hands, painful blue fingers/toes during the cold, GERD and dysphagia with solids and liquids, ulcers and calcium deposits on hands, and multiple red markings on skin

Diffuse scleroderma (autoimmune deposition of collagen with fibrosis in various organs/tissues --> due to immune reaction against mesenchymal antigen, which causes dysfunctional endothelial cells --> increased expression of CAMs causes inflammatory cells to invade CT, while increased endothelin release causes vasoconstriction and ischemia leading to end-organ damage --> endothelial cells also secrete PDGF and TGF-beta which activate fibroblasts and cause fibrosis around blood vessels --> DIFFUSE type involves blood vessels causing Raynaud's, GI tract causing delayed emptying of stomach/small bowel malabsorption/esophageal dysmotility, heart causing right-sided HF and cardiac fibrosis, and kidneys causing sclerodermal renal crisis --> diagnosis: anti-DNA topoisomerase I antibodies --> most common cause of death: lung involvement with interstitial fibrosis and pulmonary HTN)

Middle-aged woman with thick tight skin throughout body, GERD and dysphagia with solids and liquids, Raynaud's phenomenon, and right-sided heart failure

Asbestosis (occupational lung disease due to exposure to shipbuilding, roofing, plumbing with inhalation of asbestos --> causes interstitial pulmonary fibrosis and plaques in LOWER LOBES --> CXR shows reticulonodular pulmonary infiltrates indicating pulmonary fibrosis from chronic inflammation --> CT scan shows "ivory white" calcified supradiaphragmatic and pleural plaques --> alveolar sputum shows ferruginous bodies, aka golden-brown fusiform rods resembling dumbbells visualized using Prussian blue stain --> complications: Caplan syndrome with rheumatoid arthritis, pleural effusions, bronchogenic carcinoma, mesothelioma)

Middle-man who works in a shipyard presents with progressive dyspnea, bilateral basilar crepitant crackles, CXR shows reticulonodular pulmonary infiltrates

Hypertension, smoking, diabetes, and dyslipidemia (high LDL, low HDL)

Modifiable risk factors for atherosclerosis

Chronic transmural inflammation (associated with aging, smoking, male sex, HTN, family history --> leads to oxidative stress, vascular smooth muscle apoptosis, and chronic transmural inflammation of aorta --> macrophages release MMPs and elastases that degrade ECM, leading to weakening and progressive expansion of aortic wall --> also associated with atherosclerotic thickening of intimal layer, which increases diffusion distance for O2 and causes ischemia of tunica media --> results in pathologic dilatation of aorta, usually located BELOW renal arteries and ABOVE aortic bifurcation)

Most common cause of abdominal aortic aneurysm

CMV (cytomegalovirus, aka HHV-5: part of herpesvirus family, aka enveloped linear dsDNA virus --> can cause non-calculous cholecystitis in transplant patients, especially after renal transplant --> presents with fever, persistent RUQ pain, leukocytosis, Murphy sign aka inspiratory pause during deep palpation of RUQ due to pain with pain possibly radiating to right shoulder --> diagnosis: ultrasound or HIDA scan --> complications: chronic cholecystitis, ascending cholangitis, porcelain calcified gallbladder that can lead to cholangiocarcinoma)

Most common cause of acalculous cholecystitis in transplant patients

Hypertension (high hydrostatic pressure thru capillaries causes PROTEIN LEAK from blood vessel lumen into vessel wall, which causes hyaline arteriolosclerosis aka vascular thickening with pink hyaline material within intima --> this often occurs in VASA VASORUM within adventitia of proximal 10cm of aorta, which provides blood to outer 1/2 of aortic wall --> hyaline arteriolar thickening results in REDUCED VESSEL CALIBER and decreased blood flow --> causes atrophy of outer 1/2 of wall, which includes smooth muscle --> this results in WEAKENING OF MEDIA within proximal aortic wall, predisposing it to longitudinal tear that causes blood to flow into vessel wall and form false lumen within media --> presents with tearing sudden-onset chest pain that radiates to back and unequal BP in arms --> CXR shows mediastinal widening --> complications: organ ischemia, aortic rupture/hemorrhage, pericardial tamponade --> most common cause of death: pericardial tamponade due to backwards flow of blood within false lumen into pericardium)

Most common cause of aortic dissection

HBV (hepatitis B: hepadnavirus that is a naked, circular, partially dsDNA virus with a reverse transcriptase --> transmitted via sexual intercourse or perinatally during birth --> usually resolves in adults, HOWEVER majority of HBV cases in developing countries acquired thru vertical transmission during childbirth --> neonates with HBV more likely to develop chronic infection and eventual HCC --> can prevent with universal vaccination)

Most common cause of hepatocellular carcinoma worldwide

Viral illness (cause about 85% of pericarditis cases --> usually associated with Coxsackie B --> can also be caused by autoimmune diseases such as SLE/rheumatoid arthritis, uremia from kidney failure, post-MI fibrinous pericarditis or Dressler syndrome, or radiation therapy)

Most common cause of idiopathic pericarditis

Pseudomonas aeruginosa (non-lactose-fermenting, oxidase-positive, catalase-positive, motile gram-negative rod with grape-like odor: transmitted via contaminated water --> contains mucoid polysaccharide capsule that forms biofilm, PLC that degrades cell membranes, endotoxin that causes fever/shock, exotoxin A that inactivates EF2/causes cell death, and pyoverdine/pyocyanin pigments that generate ROS --> associated with OTITIS EXTERNA, pneumonia in cystic fibrosis patients, nosocomial infections, sepsis, UTIs, and severe skin infections such as hot tub folliculitis/burn-related infections/ecthyma gangrenosum --> associated with cystic fibrosis, immunocompromised, diabetics, IV drug users --> treat with CAMPFIRE drugs: Carbapenems, Aminoglycosides, Monobactams, Polymyxins, Fluoroquinolones, thIRd/fourth gen cephalosporins like ceftazidime and cefepime, Extended-spectrum penicillins such as piperacillin and ticarcillin)

Most common cause of otitis externa (swimmer's ear)

Cystic medial degeneration (associated with connective tissue diseases such as Marfan and Ehlers-Danlos, HTN, bicuspid aortic valve --> thoracic aortic aneurysm can also be associated with 3° syphilis, which causes obliterative endarteritis of vasa vasorum --> results in aortic root dilatation that may lead to aortic valve regurgitation)

Most common cause of thoracic aortic aneurysm

Serous cystadenocarcinoma (MALIGNANT ovarian surface epithelial tumor that is often BILATERAL --> usually presents in ELDERLY WOMEN with adnexal mass, ascites, peritoneal metastasis that results in decreased appetite, abdominal distension, and bowel/bladder changes --> biopsy shows anaplasia of epithelial cells with invasion into stroma, multiple papillary formations with cellular atypia, and Psammoma bodies --> associated with CA-125 tumor marker, which is useful for monitoring response to therapy/relapse but NOT useful for screening)

Most common ovarian cancer

Merkel cell carcinoma (rare skin cancer arising from Merkel cells, aka neuroendocrine receptors in skin associated with touch --> presents as flesh-colored or bluish-red nodules on face/head/neck)

Multiple bluish-red skin nodules on face, head, neck

Marantic endocarditis (non-bacterial thrombotic endocarditis/NBTE: formation of sterile platelet-rich thrombi attached to mitral valve leaflets --> associated with cancer especially pancreatic or mucinous adenocarcinomas, SLE, and hypercoagulable states such as antiphospholipid syndrome/DIC/extensive burns --> initial valvular endothelial injury caused by inflammatory cytokines triggers platelet deposition --> formation of NBTE vegetations consisting of bland white thrombus with strands of fibrin/ICs/macrophages --> usually asymptomatic, but can cause systemic emboli resulting in stroke or acute limb ischemia --> NOTE: SLE/Libman-Sacks endocarditis usually associated with vegetations on BOTH sides of valve)

Multiple small, non-destructive masses composed of platelet-rich thrombi attached to edges of mitral valve leaflets

Rheumatic heart disease (sequelae of group A strep pharyngitis: type 2 HSR due to formation of antibodies against strep M protein, which cross-reactions with self-antigens throughout the body, especially the HEART --> presents with migratory polyarthritis, subcutaneous skin nodules, erythema marginatum aka evanescent rash with ring margin, Sydenham chorea, and new onset of mitral regurgitation murmur --> biopsy of myocardium shows Aschoff bodies, aka granulomas with giant cells, and Anitschkow cells, aka enlarged macrophages with snake-like nuclei --> diagnosis: elevated ASO titer, aka anti-streptolysin O antibodies --> complication: mitral stenosis, often seen in IMMIGRANTS with untreated rheumatic heart disease --> treat with penicillin)

Myocardial biopsy shows small foci of multinucleated giant cells and enlarged macrophages with ovoid wavy rod-like nuclei

Adenomatous and serrated (BOTH types have ability to transform to colonic adenocarcinoma, polyp size >10cm most important risk factor for malignancy risk --> adenomatous: formed via chromosomal instability pathway with mutations in APC/KRAS, villous histology more malignant --> serrated polyps: formed via CpG island methylator phenotype that may silence DNA mismatch repair genes, mutations may lead to microsatellite instability and mutations in BRAF, "sawtooth" pattern of crypts on biopsy)

Neoplastic colonic polyps

Necrotizing enterocolitis (necrosis of intestinal mucosa in PREMATURE NEWBORNS who are formula-fed and have immature immune systems --> usually seen in terminal ileum and proximal colon --> may cause perforation of bowel, which can lead to pneumotaosis intestinalis, aka gas in bowel wall --> CXR will show pneumoperitoneum and portal venous gas)

Newborn abdominal XR shows gas in the bowel wall and portal venous gas

Pure esophageal atresia (EA: narrowing or break of esophagus so that food cannot enter stomach and is immediately expelled via mouth --> presents IN UTERO with polyhydramnios --> presents in NEWBORNS with drooling/choking/vomiting and cyanosis 2° to laryngospasm to avoid reflux-related aspiration --> CXR shows gasless abdomen due to lack of air entering GI tract --> diagnosis: failure to pass nasogastric tube into stomach)

Newborn who immediately drools/chokes/vomits after first feeding, CXR shows gasless abdomen

EA with distal TEF (espophageal atresia with distal tracheoesophageal fistula: most common type of TE anomaly -->

Newborn who immediately drools/chokes/vomits after first feeding, cyanosis, CXR shows air in stomach

Placental aromatase deficiency (autosomal recessive disorder characterized by inability to synthesize estrogens from androgens in placenta --> causes HIGH androgens and LOW estrogen in female fetus --> androgens crossover placenta and cause maternal virilization/hirsutism during pregnancy --> newborn girls will have normal internal genitalia, ambiguous or male-type external genitalia, and elevated serum testosterone and androstenedione --> at puberty, impaired ovarian estrogen synthesis causes primary amenorrhea, tall stature due to low estrogen delaying fusion of epiphyses, and osteoporosis)

Newborn with 46XX genotype presents with ambiguous genitalia and clitoromegaly, normal uterus, elevated testosterone and andostenedione, mother admits to facial hair growth/deep voice during pregnancy

Unbalanced Robertsonian translocation (inherited disorder that causes 5% of Down syndrome cases: asymptomatic parent has BALANCED Robertsonian translocation between acrocentric chromosomes 14 and 21, resulting in fusion of long arms 14q21q and short arms 14p21p --> short arm 14p21p usually contains non-essential genetic material and is lost after several divisions, while long arm 14q21q remains --> affected parent is ASYMPTOMATIC because chromosome count is normal, just abnormally rearranged --> however, when maternal gamete with one 14q21q chromosome and one normal 21st chromosome is fertilized by normal sperm, it results in fetus having 46 chromosomes but 3 copies of chromosome 21 --> can also result in maternal gametes having 0 copies of chromosome 21, resulting in non-viable fetus --> presents in mothers with recurrent spontaneous abortions and children with Down syndrome)

Newborn with 46XX, t(14;21)

Mullerian inhibitory factor deficiency (OR absence of Sertoli cells: without MIF or Sertoli cells, cannot suppress development of Mullerian/paramesonpehric ducts --> development of internal female reproductive organs occurs --> however, functional Leydig cells will still produce testosterone so there will ALSO be male internal reproductive organs and production of male external genitalia)

Newborn with 46XY karyotype presents with both male and female internal genitalia, and male external genitalia

Androgen insensitivity syndrome (AIS: normal Sertoli/Leydig cells and normal testosterone levels but defect in ANDROGEN RECEPTOR, therefore unable to respond to testosterone --> results in 46XY patients becoming normal-appearing females due to excess testosterone converted to estradiol via aromatase --> presents with female external genitalia, absent Fallopian tubes and uterus, scant axillary/pubic hair, rudimentary vagina, amenorrhea and infertility, and possible palpable mass in labia majora indicating undescended testes --> lab findings: ↑LH, ↑testosterone, ↑estrogen --> treatment: need to remove testes from labia majora to prevent malignancy)

Newborn with 46XY karyotype, absent internal genitalia, and female external genitalia

5-alpha-reductase deficiency (autosomal recessive disorder characterized by inability to convert testosterone to DHT --> 46XY males present with normal internal genitalia, but ambiguous external genitalia ranging from small phallus with hypospadias to female-type genitalia --> excess testosterone during puberty causes masculinization and results in increased growth of scrotum/penis, testicular descent, male-pattern muscle mass, voice deepening --> lab findings: NORMAL testosterone, estrogen, LH)

Newborn with 46XY phenotype, male internal genitalia, and ambiguous external genitalia

Meconium ileus (meconium plug causes obstruction of intestine --> prevents stool passage at birth --> associated with CYSTIC FIBROSIS)

Newborn with abdominal distension, increasing distress, no bowel movements since birth, CXR shows small bowel obstruction, family history of cystic fibrosis

Jejunal and ileal atresia (due to vascular occlusion of mesenteric vessels in utero, usually of SMA --> ischemic necrosis of fetal intestinal segment --> causes luminal narrowing/stenosis or obliteration/atresia --> results in PROXIMAL segment ending in a blind pouch, followed by an area of absent small bowel/associated dorsal mesentery, and distal segment assuming spiral configuration around an ileocolic vessel known as "christmas tree" or "apple peel" deformity --> CXR shows dilated loops of small bowel with air-fluid levels)

Newborn with bilious emesis and abdominal distention, dehydration, and laparatomy shows normal-appearing duodenum, absence of large segment of jejunum/ileum, and remainder of distal ileum winding around a thin vascular stalk

Unilateral renal agenesis (due to failure of one ureteric bud to develop --> cannot induce differentiation of metanephric blastema --> complete absence of kidney/ureter --> usually asymptomatic with compensatory hypertrophy of contralateral kidney, but can be associated with anomalies in contralateral kidney)

Newborn with complete absence of unilateral kidney and ureter

Edwards syndrome (trisomy 18: 2nd most common autosomal trisomy resulting in live birth, after Down syndrome --> usually arises due to meiotic nondisjunction with maternal age >35y/o --> presents with PRINCE Edward: prominent occiput, rocker bottom feet, intellectual disability, nondisjunction, clenched fists with overlapping fingers, ears that are low-set --> also associated with micrognathia, omphalocele, congenital heart defects, horseshoe kidney, cataracts --> lab findings-1st trimester: ↓b-HCG and ↓PAPP-A --> lab findings-2nd trimester: ↓b-HCG, normal or ↓inhibin A, ↓estriol and ↓AFP --> poor prognosis with death usually occurring by age 1)

Newborn with enlarged back of skull, small mouth and jaw, low-set ears, clenched hands with overlapping fingers, swollen feet, hypertonia

Down syndrome (trisomy 21: 95% due to meiotic nondisjunction due to advanced maternal age, 5% due to unbalanced Robertsonian translocation, 1% due to postfertilization mitotic error --> causes intellectual disability, flat facies, prominent epicanthal folds, single palmar crease, incurved 5th finger, gap between 1st and 2nd toes, Brushfield spots in iris of eye --> associated with duodenal atresia, Hirschsprung disaease, AV septal defect such as VSD --> diagnosis in utero: 1st trimester ultrasound shows nuchal translucency and hypoplastic nasal bone, chorionic villus sampling shows 47XX/XY+21 karyotype, 1st trimester shows ↑b-HCG and ↓PAPP-A, while 2nd trimester shows ↑b-HCG, ↑inhibin A, ↓estriol and ↓AFP --> complications: early-onset Alzheimer disease due to extra copy of APP gene, risk of ALL or AML)

Newborn with epicanthal folds, upslanting palepbral fissures, protruding tongue, excessive skin at nape of neck, hypotonia, weak startle (Moro) reflex

Osteogenesis imperfecta (type I collagen defect: COLIA1/COLIA2 gene mutations --> loss of type I collagen, which is mostly found in bone, but also in skin, tendon, dentin, fascia, and cornea --> blue sclera due to exposure of choroidal veins --> hearing loss to due abnormal ossicles in ear --> dentinogenesis imperfecta due to lack of dentin --> treat with bisphosphonates to decrease fracture risk)

Newborn with macrocephaly and poor skull mineralization, shortened extremities with misshaped long bones, and several fractures that occurred during birth

Patau syndrome (trisomy 13: usually arises due to meiotic nondisjunction with maternal age >35y/o --> additional chromosome 13 causes defect in prechordal mesoderm, an integral embryologic structure affecting growth of midface/eyes/forebrain --> presents with severe intellectual disability, rocker-bottom feet, abnormally small eyes/microphthalmia, microcephaly, cleft lip/palate, holoprosencephaly aka lack of separation between cerebral hemispheres, cutis aplasia aka lack of skin --> associated with congenital heart disease, horseshoe kidney, omphalocele, cataracts --> lab findings-1st trimester: ↓b-HCG and ↓PAPP-A but unreliable quad screen during 2nd trimester --> poor prognosis with death usually occurring by age 1)

Newborn with microcephaly, holoprosencephaly and cyclopia, cleft lip and cleft palate, polydactyly, and small round punched-out lesion with overlying thin membrane on scalp

Propionic acidemia (autosomal recessive deficiency of propionyl-CoA carboxylase --> unable to metabolize odd-chain fatty acids, branched-chain AAs, methionine, and threonine into methylmaloyl-CoA to enter TCA cycle as succinyl-CoA --> excess propionyl-CoA then converted to propionic acid, which builds up in bloodstream --> accumulation of propionic acid becomes toxic and damages brain/heart/liver and causes seizures and delays to normal development --> presents in NEWBORNS with poor feeding, vomiting, hypotonia, seizures, hepatomegaly, and metabolic acidosis with increased anion gap --> treat with LOW-PROTEIN DIET that does not include "VOMIT" aka valine, odd-chain fatty acids, methionine, isoleucine, threonine)

Newborn with poor feeding, vomiting, hypotonia, seizures, hepatomegaly, metabolic acidosis with increased anion gap

Propionic acidemia (autosomal recessive deficiency of propionyl-CoA carboxylase, which normally converts propionyl-CoA into methymalonic acid to form succinyl-CoA and feed into TCA cycle --> elevated propionyl-CoA and low methylmalonic acid, causing severe metabolic acidosis and ketotic hypoglycemia with increased anion gap --> since the AAs valine, isoleucine, methionine, threonine can be broken down into propionyl-CoA, treatment is a low-protein diet without these substances --> NOTE: cholesterol, odd-chain fatty acids, thymidine, and uracil can also be broken down into propionyl-CoA)

Newborn with progressive lethargy, vomiting, poor feeding, somnolent with decreased muscle tone, metabolic acidosis with elevated anion gap, ketosis, hypoglycemia, hepatomegaly

Multicystic kidney dysplasia (congenital kidney disorder in which one ureteric bud fails to induce differentiation of metanephric mesenchyme --> formation of non-functional kidney with cysts of varying size and connective tissue --> also associated with absence of normal pelvocaliceal system , aka ureteral atresia or ureteropelvic atresia)

Newborn with unilateral kidney consisting of cysts and connective tissue and ureteral atresia

Hyperplastic, inflammatory, submucosal, juvenile (hyperplastic polyps: small polyp composed of well-differentiated mucosal cells that form glands/crypts, most common and often located in rectosigmoid region --> inflammatory polyps: due to mucosal erosion in ulcerative colitis/Crohn disease and composed of regenerating intestinal mucosa and inflammatory cells --> submucosal polyps: composed of lipomas/fibromas or lymphoid aggregates that bulge up into mucosa --> juvenile polyps: hamartomatous GI polyps characterized by growth of normal colonic tissue with distorted architecture, can be sporadic with no risk of CRC or multiple in Peutz-Jegher/juvenile polyposis syndrome with increased risk of CRC)

Non-neoplastic colonic polyps

Extrinsic restrictive lung disease (usually due to OBESITY, also associated with neuromuscular disease --> increased fat within chest wall prevents lung expansion, causing reduced lung volume --> decreases FEV1 and FVC individually, but causes normal or INCREASED FEV1/FVC ratio --> since the problem is EXTRINSIC to lung, no change in diffusion capacity)

PFT findings: Normal or ↑FEV1/FVC ↓TLC Normal DLCO

Piriformis syndrome (occurs due to muscle injury or hypertrophy of piriformis, which occupies the greater sciatic foramen --> can compress sciatic nerve located BELOW piriformis --> presents with sciatica-like symptoms and tender muscle with deep palpation or on stretching with adduction/internal rotation)

Pain/tingling in buttocks and posterior thigh, difficulty lifting heavy objects and climbing stairs, pain with forced adduction of flexed thigh and internal rotation of extended thigh against resistance

Glomus tumor (BENIGN tumor arising from modified smooth muscle cells of thermoregulatory glomus body --> presents as painful red-blue tumor under fingernails)

Painful red-blue tumor under the fingernails

First degree burn (superficial burn that only involves epidermis --> presents as painful red DRY burn without any blisters --> heals well within 5-10 days --> ex: common sunburn)

Painful, dry, erythematous burn without blisters

Second degree burn (partial-thickness burn through epidermis and dermis, with edema and hyperemia of tissues beneath the burn --> presents as painful red/yellow/white MOIST burn with clear blisters that blanche with pressure --> usually heals without scarring, but risk of cellulitis and burn scar contractures)

Painful, moist, erythematous burn with clear blisters

Third degree burn (full-thickness burn extending through epidermis, dermis, and hypodermis --> presents as stiff white/brown LEATHERY or WAXY-appearing burn without any blisters or blanching --> usually causes SKIN SCARS with wound healing --> risk of burn scar contractures and amputation)

Painless, leathery-appearing white/brown burn without blisters or blanching

Cretinism (congenital hypothyroidism: severe fetal hypothyroidism due to antibody-mediated maternal hypothyroidism, thyroid agenesis/ectopy/hypoplasia, iodine deficiency, or dyshormonogenetic goiter --> presents with 6 P's: pot-bellied, pale, puffy-faced child with protruding umbilicus, protuberant tongue, and poor brain development)

Pale, puffy-faced, pot-bellied child with protruding umbilicus, enlarged tongue, and intellectual disability

Vitamin D intoxication (occurs when excessive vitamin D supplementation causes symptomatic hypercalcemia, associated with "stones, thrones, bones, groans, psychiatric overtones" --> results in impaired depolarization of neuromuscular membranes causing muscle weakness, constipation, and confusion --> also impairs urine concentration in DCT and causes Ca2+ deposition in collecting ducts, resulting in polyuria/polydipsia and possible renal failure --> abdominal/flank pain can be associated with calcium kidney stones from hypercalciuria, or acute pancreatitis --> treat with cessation of vitamin D use and bisphosphonates --> NOTE: hypercalcemia also associated with Williams syndrome, sarcoidosis, parathyroid adenoma/MEN2, paraneoplastic PTHrP from RCC and SCC of lung, nephrogenic DI, adult T-cell lymphoma, multiple myeloma --> can also be caused by drugs such as Foscarnet, calcium carbonate antacid, succinylcholine, thiazide diuretics)

Patient being treated for osteoporosis presents with progressive lethargy, loss of appetite, constipation, muscle weakness, increased thirst/urination, dry mucous membranes

Lepromatous leprosy (LL: caused by Mycobacterium leprae, and acid-fast bacillus that prefers COOLER BODY TEMPS and therefore infects skin and superficial nerves --> transmitted via respiratory route OR direct skin-to-skin contact, also associated with armadillos in SW USA --> lepromatous leprosy is MOST SEVERE form due to weak cell-mediated response and dependence on Th2 response, which does not activate macrophages very well leading to mycobacterial dissemination --> presents with DIFFUSE skin thickening and hypopigmented plaques, hair loss, lion-like facies, widespread paresis, regional anesthesia, testicular destruction, and blindness --> diagnosis: skin biopsy shows LARGE # of bacteria due to high bacterial load, invasion into superficial nerves --> treat with dapsone + rifampin + clofazimine for 2-5yrs)

Patient from East Africa presents with diffuse skin thickening, plaque-like hypopigmentation with hair loss, leonine facies with loss of eyebrow hair/eyelashes, collapse of nose, and formation of nodular ear lobes

Tuberculoid leprosy (TT: caused by Mycobacterium leprae infection, an acid-fast bacillus that prefers COOLER BODY TEMP and therefore infects skin and superficial nerves --> transmitted via respiratory route OR direct skin-to-skin contact, also associated with armadillos in SW USA --> tuberculoid leprosy is LEAST severe form of leprosy and often self-limited due to robust cell-mediated/Th1 response, which reduces bacterial load --> presents with mild skin plaques associated with hypopigmentation, hair follicle loss, and focally decreased sensation --> screening: positive lepromin skin test due to Th1 response --> diagnosis: skin biopsy shows organisms invading superficial nerves such as Schwann cells --> treat with dapsone and rifampin)

Patient from East Africa presents with hypopigmentation of skin on upper extremities, tingling sensation in hands, and patchy areas of skin anesthesia

Behcet syndrome (small-vessel vasculitis caused by immune complex deposition: high incidence in Turkish/eastern Mediterranean descent, associated with HLA-B51 --> presents with EPISODES of recurrent aphthous ulcers, genital ulcers, uveitis, and erythema nodosum, can be precipitated by HSV or parvovirus B19 --> flares are usually self-resolving and last 1-4wks)

Patient from Turkey with recent viral illness presents with mouth ulcers, genital ulcers, uveitis, and bilateral tender red nodules on shins

Amebiasis (caused by Entamoeba histolytica infection: GI protozoan transmitted by cysts in water that differentiate into trophozoites in GI tract --> trophozoites invade colon via contact-dependent host cytotoxicity, aka insertion of amebic channel-forming protein in host cell membrane that causes cell death, resulting in flask-shaped ulcers in colon --> spread to liver via portal circulation to cause liver abscesses, usually in right lobe --> diagnosed by serology to detect anti-Entamoeba Abs, ELISA Ag testing, stool containing trophozoites with engulfed RBCs in cytoplasm, or stool containing cysts with up to 4 nuclei --> colon biopsy shows flask-shaped ulcers --> treat acute infection with metronidazole, asymptomatic cyst passers with paromycin or iodoquinol)

Patient from Uganda presents with fever, frequent slimy stools with mucus, mild tenderness of RUQ, colonoscopy shows multiple ulcers that have undermined and destroyed large areas of intestinal epithelium

Patella fracture (caused by direct blow to anterior aspect of knee, OR from excessive force transmitted thru quadriceps tendon such as landing on feet after falling from height --> injury to patella prevents knee EXTENSION --> NOTE: hamstring injury would damage knee flexion as well as hip extension)

Patient in MVA presents with severe left knee pain, contusion and soft-tissue swelling at knee, palpable gap in extensor mechanism, inability to ambulate, inability to EXTEND knee against gravity

Radial nerve injury in axilla (known as "crutch palsy:" compression of axilla from crutches or sleeping with arm over chair causes injury to very proximal radial nerve, causing loss of almost all of its function --> presents with wrist drop aka loss of elbow/wrist/finger extension, decreased grip strength, absent triceps reflex, and loss of sensation over posterior arm/forearm/dorsal hand)

Patient on crutches presents with weakness of forearm/hand, loss of finger and wrist extension, absent triceps reflex, sensory loss over posterior arm/forearm/dorsal hand

LMN Bell's palsy (damage to facial nucleus in pons OR anywhere along CN7 --> causes muscles of facial expression weakness on IPSILATERAL SIDE, includes BOTH upper/lower muscles and INCLUDES FOREHEAD --> also causes incomplete eye closure due to dry eyes/corneal ulceration, hyperacusis, and loss of taste sensation on anterior 2/3 of tongue)

Patient presents with unilateral weakness of facial muscles including forehead, dry eyes, corneal ulcers, increased sensitivity to loud sounds, and loss of taste sensation

UMN Bell's palsy (damage in pathway from motor cortex to facial nucleus in pons --> causes LOWER muscles of facial expression weakness on CONTRALATERAL side and SPARES FOREHEAD --> no other symptoms)

Patient presents with unilateral weakness of lower facial muscles with sparing of forehead

Ecthyma gangrenosum (EG: rapidly progressive necrotic cutaneous lesions caused by Pseudomonas in patients with neutropenia, especially if ANC <500 --> Pseudomonas causes perivascular bacterial invasion of arteries/veins in dermis and subcutaneous tissue --> release of exotoxins such as exotoxin A that inhibits protein synthesis, elastase that causes blood vessel destruction, phospholipase C that degrades cell membranes, and pyocyanin that generates ROS --> results in insufficient blood flow and destruction of human tissue, leading to skin patches with necrosis and ulceration --> can eventually cause sepsis --> treat Pseudomonas with CAMPFIRE drugs: carbapenems, aminoglycosides, monobactams, polymyxin B, fluoroquinolones such as ciprofloxacin/levofloxacin, thiRd/4th gen cephalosporins such as cefepime or ceftazidime, and extended-spectrum penicillins such as piperacillin/ticarcillin)

Patient taking chemotherapy for AML presents with fever, chills, hypotension, tachycardia, multiple skin patches with necrotic centers and occasional ulcerations

Neuroleptic malignant syndrome (occurs in patients with genetic predisposition who are taking anti-psychotics or metroclopramide --> inhibition of dopamine receptors causes abnormal functioning of basal ganglia, increased SNS activation, and increase muscle activity --> presents with high fever, mental status changes, muscle rigidity and rhabdomyolysis, encephalopathy --> treat with dantrolene and bromocriptine)

Patient taking metroclopramide presents with sudden onset of high fever, confusion, muscle rigidity, unstable vitals, mental status changes, myoglobinuria, elevated CK

Right optic nerve lesion (Marcus Gunn pupil, aka relative afferent pupillary defect/RAPD: due to injured optic nerve, which impairs conduction of light signal --> when light shines onto normal eye, there is constriction of both eyes BUT when light shines onto affected eye, but pupils dilate instead of constrict --> associated with acute optic neuritis in multiple sclerosis)

Patient that can constrict both eyes when light is shined on the LEFT EYE, but causes dilation of both eyes when light is shined on the RIGHT EYE

Acute interstitial nephritis (tubulointerstitial nephritis: occurs due to drugs that act as haptens inducing a type 4 HSR with T-cell mediated attack on renal tubular cells --> associated with penicillins/cephalosporins, diuretics, NSAIDs, PPIs, rifampin, and sulfa drugs --> may also be 2° to mycoplasma infection, Sjogren, SLE, sarcoidosis --> causes acute inflammation of RENAL INTERSTITIUM, resulting in intrinsic renal failure --> presents with fever, diffuse petechial rash, high serum eosinophils, hematuria, pyuria and WBC casts with EOSINOPHIILS, costovertebral angle tenderness --> kidney biopsy shows severe tubular damage with interstitial edema and T-cell/eosinophilic infiltrate --> usually resolves with removal of offending agent)

Patient who begins taking penicillin presents with fever, diffuse petechial rash, CVA tenderness, hematuria, pyuria, WBC casts

Global cerebral ischemia (GCI: rapid cessation of cerebral blood flow --> if it lasts longer than 3-5mins, can cause irreversible damage to vulnerable neurons, usually pyramidal neurons of hippocampus + pyramidal neurons in layers 3/5/6 of neocortex + Purkinje cells of cerebellum --> these neurons are located in "watershed zones" between 2 diff cerebral arteries and highly susceptible to damage if ischemia sustained for 5-10mins --> presents with loss of consciousness/coma --> diagnosis: diffusion-weight MRI to detect ischemia within 3-30mins)

Patient who experienced acute MI with ventricular fibrillation presents with stable vital signs but does not follow commands or respond to strong stimuli

Cold diuresis (occurs during HYPOTHERMIA: caused by peripheral vasoconstriction which redirects blood from the extremities to the CENTRAL body, thus increasing central blood volume --> atrial myocytes sense increased blood volume and secrete ANP, resulting in RAAS inhibition and vasodilation of arteries --> inhibition of aldosterone and ADH cause decreased Na+ and H2O reabsorption, and dilation of AFFERENT arterioles/constriction of EFFERENT arterioles promotes diuresis to compensate for increased blood volume --> lab findings: ↑central blood volume, ↑ANP, ↓aldosterone, ↓ADH)

Patient who has been trapped in cold water for 20 minutes presents with decreased ADH and elevated ANP

Hemothorax (hemorrhaging blood into pleural cavity, aka space between chest wall and lung --> blood within pleural cavity interferes with lung expansion, resulting in dypsnea, poor ventilation, and abnormal oxygenation --> treatment: thoracocentesis to remove blood)

Patient with blunt chest trauma presents with hypotension, tachycardia, tachypnea, unilateral absent breath sounds and dullness to percussion

Arsenic poisoning (occurs from exposure to pesticides/insecticides, contaminated water from wells, pressure-treated wood, metallurgy, mining, or glass-making --> arsenic binds to sulfhydryl groups to inhibit lipoic acid in pyruvate dehydrogenase/block TCA cycle, disrupt gluconeogenesis, and impair glutathione metabolism --> ACUTE arsenic poisoning presents with abdominal pain, vomiting, severe watery diarrhea and hypotension from dehydration, delirium, QT prolongation, and GARLIC ODOR in breath/stool --> CHRONIC arsenic poisoning presents with hypopigmentation of skin, hyperkeratosis, stocking-glove neuropathy, and increased risk of squamous cell carcinoma of skin/liver angiosarcoma --> treat with dimercaprol, which increases urinary excretion of heavy metals and allows chelation)

Patient who ingested insecticide presents with nausea, vomiting, abdominal pain, watery diarrhea, hypotension, tachycardia, faint garlic odor

Lymphedema (obstruction of lymphoid capillaries that results in marked swelling of dorsum of distal limb that may extend proximally --> due to inability to drain interstitial fluid, resulting in increased fluid/oncotic pressure within interstitium that furthers pulls out water from capillaries --> initially presents with soft pitting edema, but progressive fibrosis/thickening of overlying skin eventually results in in firm non-pitting edema --> associated with Turner syndrome, inflammatory IDC into dermal lymphatics, lymph node dissection, radiation therapy, and lymphatic filiarisis/elephantiasis from Wucheria bancrofti infection of lymph nodes)

Patient who initially presented with soft pitting edema of bilateral legs now presents with thickened, firm, non-pitting edema

Anaplasmosis (caused by Erlichia chaffeensis, a zoonotic bacteria --> transmitted via Ixodes tick which also causes Lyme disease/Babesiosis, located in southeastern USA --> presents in OUTDOORSY people/GOLF communities with high fever, headaches, muscle aches, N/V --> lab findings: normal RBCs, low platelets, low neutrophils, low lymphocytes --> peripheral smear shows MORULAE aka mulberry-like inclusions in cytoplasm of NEUTROPHILS --> treat with doxycycline)

Patient who is an avid golfer presents with high fever, headache, nausea, vomiting, muscle aches, thrombocytopenia, leukopenia, lymphopenia, elevated AST/ALT, peripheral smear shows granulocytes with mulberry-like inclusions in cytoplasm

Erlichiosis (caused by Erlichia chaffeensis, a zoonotic bacteria --> transmitted via Amblyomma, aka Lone Star tick, located in south central/southeastern USA --> presents in OUTDOORSY people/GOLF communities with high fever, headaches, muscle aches, N/V --> lab findings: normal RBCs, low platelets, low neutrophils, low lymphocytes --> peripheral smear shows MORULAE aka mulberry-like inclusions in cytoplasm of MACROPHAGES --> treat with doxycycline)

Patient who is an avid golfer presents with high fever, headache, nausea, vomiting, muscle aches, thrombocytopenia, leukopenia, lymphopenia, elevated AST/ALT, peripheral smear shows monocytes with "mulberry-like" inclusions in cytoplasm

SMA syndromee (compression of TRANSVERSE portion of duodenum between aorta and SMA at L3 --> usually protected by mesenteric fat, which can get diminished in anorexia, recent weight loss, severe burns, prolonged bed rest, or after surgery for scloliosis --> causes angle between SMA and aorta to narrow <20°, resulting in entrapment of transverse duodenum and causing small bowel obstruction --> presents with severe nausea, bilious vomiting, postprandial epigastric pain/early satiety, high-pitched bowel sounds)

Patient who recently experienced extreme weight loss presents with severe postprandial epigastric pain, early satiety, nausea, bilious vomiting, and high-pitched bowel sounds

Fat embolus (occurs due to long bone fractures, soft tissue trauma, and liposuction --> lipids tend to dislodge and occlude pulmonary vessels --> classically presents with dyspnea and petechial rash overlying skin of chest, possible CNS symptoms --> biopsy of embolus shows white lipid droplets)

Patient who recently fractured foot presents with dyspnea and petechial rash overlying skin of chest

Cholera (caused by V. cholerae: flagellated, oxidase-positive, comma-shaped gram-negative bacteria that grows in ALKALINE media --> endemic to developing countries and transmitted via ingestion of contaminated water or raw shellfish --> cholera enterotoxin permanently activates Gs on intestinal epithelium, increasing cAMP and increasing Cl- secretion into gut which also pulls water --> presents with voluminous "rice-water" diarrhea --> treat with oral rehydration solution --> NOTE: cholera enterotoxin is acid-labile and requires large inoculum/ID50, therefore patients with low gastric acid are highly susceptible)

Patient who recently traveled to Honduras presents with profuse watery diarrhea, fatigue, dizziness, hypotension, dry skin, decreased capillary refill

Actinomyces infection (anaerobc, branching filamentous gram-positive rod that forms yellow "sulfur granules" --> associated with oral/facial abscesses that drain thru sinus tracts, associated with dental carries/extraction and other maxillofacial trauma --> can also cause PID in patients with IUDs --> treat with penicillin)

Patient who recently underwent a dental procedure presents with chronic painless mandibular abscesses with draining sinus tracts

Amanitin toxicity (occurs due to ingestion of Amanita phalloides, aka "death cap mushrooms:" amanitins/amatoxins transported to liver via portal circulation immediately after ingestion --> active transport by OATP and NTCP transporters concentrates amatoxin within hepatocytes --> bind to DNA-dependent RNA polymerase II and INHIBIT mRNA synthesis --> results in hepatocyte apoptosis, leading to acute hepatic failure --> can also affect other organ systems with rapid cell turnover such as GI tract and PCT in kidneys --> diagnosis: urine testing for alpha-amanitin)

Patient who recently went camping and ate wild mushrooms presents with abdominal pain, vomiting, severe diarrhea, jaundice, soft tender palpable liver, elevated AST and ALT, elevated bilirubin

Contact dermatitis (caused by poison ivy, nickel allergy, or neomycin: type 4 DELAYED HSR involving cell-mediated immunity ONLY --> contact allergen triggers inflammatory reaction involving effector CD4+ T cells, which recognize antigen and release inflammation-inducing cytokines --> process takes much longer than humoral response, so causes DELAYED allergic reaction --> presents with pruritic eruptions on contacted skin occurring a few days after initial contact)

Patient who recently went hiking a few days ago presents with itchy, edematous, erythematous rash with linear vesicles on upper and lower extremities

Transtentorial hernation

Patient with sudden onset of fixed, dilated pupil

Rocky Mountain spotted fever (RMSF: caused by Rickettsia ricketsii infection --> transmitted via dog tick Dermacentor, usually found in South Atlantic states such as North Carolina --> presents with high fever, tachycardia, hypertension, petechial rash that starts at wrists/ankles and then spreads to trunk/palms/soles --> complications: septic shock and DIC leading to acute kidney injury, lung injury, meningoencephalitis --> treat with doxycycline, or chloramphenicol for pregnant women)

Patient who recently went hiking presents with a petechial rash that initially began on ankles and wrists, and is now present on trunk/palms/soles

Bubonic plague (caused by Yersinia pestis --> transmitted via fleas on rats/prairie dogs, especially in southwestern USA and Madagascar --> Y. pestis resists phagocytosis and travels to lymph nodes, where they colonize and reproduce --> lymph nodes can hemorrhage and become swollen and necrotic --> presents with high fever, chills, muscle cramps, seizures/delirium, BUBOES aka smooth painful lymph node swelling in groin/armpit/neck, LENTICULAE aka scattered black dots throughout body, gangrene of extremities --> treat with streptomycin and gentamicin, aka aminoglycosides)

Patient who recently went on a camping trip in New Mexico presents with fever, lethargy, severe muscle pain, diffuse painful swelling of neck/underarms/groin, generalized scattered black maculae, and erythematous solid tender mass above elbow that drains blood and necrotic material

Leptospirosis (caused by Leptospira interrogans: spirochere with hook-shaped ends --> transmitted via water contaminated with animal urine, prevalent among surfers and in tropical regions --> presents with flu-like symptoms, myalgias especially in calves, photophobia, and classic conjunctival suffusion aka red eyes without exudate --> can progress to Weil disease: severe form of leptospirosis with fever, jaundice and azotemia from liver/kidney dysfunction, anemia, hemorrhage)

Patient who recently went surfing in Hawaii presents with fever, chills, headache, myalgia in calves, photophobia, conjunctival suffusion

Contact dermatitis (usually caused by Toxicodendron species, aka poison ivy/poison oak --> contain allergenic compound uroshiol, which triggers type 4 HSR --> usually presents 4-96hrs after exposure with spotty papules, intensely pruritic darkly erythematous vesicles, and a linear/streaky pattern where skin brushed against the plant)

Patient who recently when on an overnight field study presents with raised erythematous spots and streaks on hands/forearms/legs

Erythema multiforme (targetoid rash: look like targets with multiple rings surrounding white dusky center, aka site of epithelial disruption/necrosis --> most commonly see in HSV infection, but also associated with Mycoplasma pneumoniae infection, drugs such as sulfa drugs/penicillin/phenytoin, cancer, autoimmune disease such as SLE --> cell-mediated IMMUNE RESPONSE with predominantly CD8+ T cells responding to antigens deposited in skin --> skin biopsy shows subepidermal blisters and degeneration of basal cell layer, keratinocyte necrosis, and lymphocytic infiltration at dermal/epidermal junction --> NOTE: differentiate from SJS by LACK OF MUCUS involvement, as SJS will usually affect extremities as well as eyes/lips and associated with fever)

Patient who started antibiotic 3 days ago presents with maculopapular rash over extremities with dusky central area, dark red inflammatory zone surrounded by a pale ring, and erythematous halo in lesion's periphery

Prepatellar bursitis ("housemaid's knee:" inflammation of prepatellar bursa in front of kneecap --> associated with repeated trauma/pressure from excessive kneeling seen in gardening, carpet layers, mechanics, plumbers --> CT scan shows inflammation in FRONT of kneecap)

Patient who works as a gardener presents with a red swollen bulge on knee with sharp localized pain on palpation, normal passive flexion/extension of knee intact, severe pain while walking

Radial nerve injury in supinator canal (associated with repetitive pronation/supination of forearm, which can cause hypertrophy of supinator muscle and compress radial nerve within supinator canal --> presents with weakness on finger/thumb extension --> triceps reflex with triceps brachii, wrist extension with ECRL, sensation to posterior arm/forearm/dorsal hand are NOT affected, as radial nerve branches supplying them emerge PROXIMAL to supinator canal)

Patient who works as a mechanic and frequently uses a screwdriver presents with weakness on extension of fingers/thumb, normal wrist extension, normal sensation of upper limb, normal triceps reflex

Air emboli (usually associated with DIVING, but can also be iatrogenic from laproscopic surgery which adds some air to blood --> causes formation of nitrogen bubbles within vasculature when divers ascend in the ocean, resulting in decompression sickness --> air emboli tend to lodge in joints/muscles and lungs --> presents with respiratory symptoms, joint pain, and muscle pain --> CHRONIC air emboli/Caisson disease causes mutifocal ischemic necrosis of bone)

Patient who works as a scuba diver presents with dyspnea, joint pain, and muscle pain

Bacillus anthracis (gram-positive, spore-forming bacterim that infects herbivores such as sheep/cows that graze on contaminated pastures --> transmitted to humans via inhalation/ingestion/cutaneous inoculation of spores --> contains polypeptide capsule which inhibits phagocytosis --> and trimeric anthrax toxin composed of protective Ag that binds to host cell membrane receptor --> delivers lethal factor--zinc metalloproteinase that inhibits MAPK to cause cell death--and edema factor, a calmodulin-dependent AC that increases cAMP to cause cellular swelling and suppression of cell function --> presents with small painless papules that rapidly ulcerate and turn into black eschar)

Patient who works in the wool business presents with a necrotic ulcer with black eschar on dorsum of right hand

Radial nerve injury in midshaft humerus (aka injury of radial groove: radial nerve enters forearm ANTERIOR to lateral epicondyle --> humeral midshaft fracture OR supracondylar fracture with anterolateral displacement of proximal segment will cause loss of radial nerve function DISTAL to elbow --> presents with wrist drop aka loss of finger/thumb/wrist extension and weakness of hand --> does NOT affect triceps reflex or sensation of posterior arm/forearm/dorsal hand, as these branches emerge PROXIMAL to injury)

Patient with a humeral fracture presents with weakness of hand, loss of finger/thumb extension, loss of wrist extension, normal triceps reflex, normal sensation over posterior arm/forearm/dorsal hand

Psittacosis (caused by Chlamydia psittaci, an obligate intracellular organism --> transmitted via aerosolized exposure to infected birds such as parrots/turkeys/pigeons --> presents with atypical pneumonia, rash, splenomegaly --> CXR shows bilateral multifocal opacities --> biopsy shows diffuse patchy inflammation localized to interstitial areas at alveolar walls)

Patient with a pet parrot presents with fever, headache, non-productive cough, malaise, skin rash, splenomegaly

Anal fissure (longitudinal tear POSTERIOR MIDLINE of anal canal below/distal to pectinate line --> due to stretching of mucosa from chronic constipation with high anal pressures/passage of hard stools, frequent diarrhea, or anal sexual intercourse --> spasm of sphincter contributes to pain and creates tension across tear, leading to chronic fissure --> most often occurs at POSTERIOR MIDLINE of anal canal below pectinate line due to poor perfusion, making mucosa sensitive to trauma/slow healing times)

Patient with chronic constipation presents with sharp severe pain on defecation with bright red blood on toilet paper

Analgesic nephropathy (chronic interstitial nephritis due to long-term NSAID use: seen in patients on high-dose NSAIDs for chronic pain, such as patients with back pain who take naproxen daily --> NSAIDs concentrate in renal medulla along medullary osmotic gradient with higher levels in papillae --> uncouple oxidative phosphorylation, causing glutathione depletion and free radical injury --> lipid peroxidation causes fibrosis/atrophy of tubular and vascular endothelial cells --> also decreases PG synthesis in afferent arterioles, causing constriction of medullary vasa recta and ischemic papillary necrosis that can develop calcifications --> presents with mildly elevated serum creatinine, mild proteinuria and sterile pyuria, evidence of tubular dysfunction with edema/polyuria/nocturia, an possible distal renal tubular acidosis/type 1 RTA with low H+ secretion and alkaline urine --> kidney biopsy shows patchy interstitial inflammation with fibrosis, tubular atrophy, papillary necrosis/scarring, and architectural distortion of calyces --> renal US shows bilaterally shrunken and irregular kidneys with papillary calcifications --> treat with cessation of NSAID use)

Patient with chronic low back pain presents with lower extremity edema, elevated BUN and creatinine, urinalysis shows protein and WBCs, renal ultrasound shows bilateral shrunken and irregular kidneys with few papillary calcifications

Dermatomyositis (autoimmune disorder with inflammatory myopathy and cutaneous involvement --> presents with proximal muscle weakness, Gottron papules, heliotrope rash, "shawl and face" rash --> muscle biopsy shows PERIMYSIAL inflammation with CD4+ T cells, patchy ischemia/necrosis, and perifascicular atrophy and fibrosis --> lab findings: increased CK, increased aldolase, positive ANA + anti-Jo-1 + anti-SRP + anti-Mi-2 --> complication: can indicate underlying adenocarcinoma, usually ovarian/breast/lung)

Patient with difficulty climbing stairs/combing hair, red flat-topped papules over joints and bony prominences of hands, and violaceous edematous eruption on upper eyelids and periorbital skin

Hemophagocytic lymphohistiocytosis (systematic overactivation of macrophages and cytotoxic T cells --> can be inherited or 2° to strong immunologic activation such as after EBV infection or cancer --> presents as fever, pancytopenia, hepatosplenomegaly --> bone marrow biopsy shows macrophages phagocytosing marrow elements --> lab findings: ↑↑↑serum ferritin levels)

Patient with fever, pancytopenia, hepatosplenomegaly, high serum ferritin levels

Corpus callosum lesion (causes "split brain" syndrome: patients cannot transfer information between hemispheres)

Patient with head injury presents with inability to use one hand to retrieve object palpated with other hand

Orbitofrontal cortex lesion (OFC: located in frontal lobe and has strong modulatory connections to limbic system, so involved in behavioral/emotional regulation --> BILATERAL lesion to OFC results in pathologic behavioral/emotional changes --> presents with impulsivity, loss of social etiquette, irritability with frank aggressive behavior)

Patient with head injury presents with personality change, social disinhibition, and irritability

Short bowel syndrome (malabsorptive condition typically occurring in patients with small bowel resection and/or Crohn disease: results in loss of absorptive surface area and decreased intestinal transit time --> malabsorption of nutrients, which normally occurs in small bowel --> results in post-prandial voluminous diarrhea and weight loss AND vitamin B12 deficiency with macrocytic anemia, characterized by peripheral neuropathy and subacute combined degeneration of spinal cord)

Patient with history of Crohn disease presents with watery diarrhea after meals, abdominal discomfort, easy fatigability, weight loss, conjunctival pallor, decreased vibration/position sense in lower extremities

Esophageal stricture (typically develops in setting of HEALING ESOPHAGEAL ULCER, when collagen fibers contract and cause narrowing of esophageal lumen --> associated with GERD, caustic ingestion, and esophagitis --> presents with dysphagia and sensation of food getting stuck in throat --> diagnosis: barium swallow, mannometry should show DECREASED LES tone)

Patient with history of GERD presents with worsening dysphagia and sensation of food getting stuck in esophagus

Reflux esophagitis (complication of GERD caused by frequent exposure to highly acidic secretions --> overwhelms esophageal mucosal defense mechanisms and results in epithelial damage --> causes erosive esophagitis with ESOPHAGEAL ULCERS --> present with worsening GERD symptoms and odynophagia --> treat with PPIs)

Patient with history of GERD presents with worsening substernal chest pain no longer relieved by antacids and painful swallowing

True ventricular aneurysm (complication of MI seen >1 month later: MI causes weakening of ventricular wall, which can result in outpouching that fills with blood --> bound by scarred myocardium that is touch and fibrotic --> can cause mural thrombus, systemic emboli, arrhythmias, and heart failure)

Patient with history of MI one month ago presents with exertional dyspnea, echocardiogram shows outward bulge of LV with contraction

Fibrinous pericarditis (pericardial inflammation with serous fluid and fibrin-containing exudate in pericardial space --> associated with idiopathic viral illness, coxsackie B infection, autoimmune diseases such as SLE or rheumatoid arthritis, uremia associated with acute/chronic renal failure, or post-MI --> causes fibrin deposition within pericardial space, which roughens visceral and parietal pericardium and causes triphasic friction during during atrial/ventricular systole and early ventricular diastole --> presents with sharp chest pain aggravated by inspiration/relieved by sitting up, pericardial friction rub, and diffuse ST elevations due to inflammation of ventricular myocardium --> complications: pericardial effusion and chronic constrictive pericarditis --> treat with NSAIDs, colchicine, or prednisone)

Patient with history of SLE presents with sharp anterior chest pain that worsens with breathing/movement, left shoulder pain, triphasic scratchy murmur heard over left sternal border with patient sitting up, EKG shows diffuse ST elevation

Diabetic gastroparesis (autonomic neuropathy of GI tract that causes delayed gastric emptying in absence of mechanical obstruction --> presents in DIABETIC PATIENTS with post-prandial nausea, vomiting of undigested food, bloating, and early satiety --> treat with metoclopramide or erythromycin)

Patient with history of T1DM presents with recurrent nausea/vomiting and upper abdominal pain after meals, early satiety, clear oropharynx/normal abdominal exam/normal upper GI endoscopy

Diabetic neuropathy (damage to CN3 due to non-enzymatic glycosylation of small blood vessels --> causes thickening of basement membrane, resulting in narrowing of vessel lumen --> often affects blood vessels supplying CN3/oculomotor nerve, causing ischemia of the nerve --> ALSO in diabetes, chronic hyperglycemia causes glucose to enter cells and get converted to sorbitol via aldolase reductase --> intracellular sorbitol accumulates within RBCs, causing osmotic damage and depletion of NADH which increases oxidative stress --> causes decreased diffusion of O2/nutrients to INFERIOR fibers from compromised vasculature residing outside of nerve --> presents with ACUTE onset of diplopia, unilateral ptosis, "down and out" gaze, and PUPIL SPARING because motor fibers affected more than PSNS)

Patient with history of T2DM presents with acute onset of diplopia, unilateral ptosis, and affected eye showing "down and out" position

Chronic pancreatitis (chronic inflammation of pancreas that results in atrophy and calcification of pancreatic parenchyma --> associated with alcohol abuse, cystic fibrosis, and pancreatic divisum --> causes pancreatic insufficiency with malabsorption of fat and fat-soluble vitamins A/D/E/K and vitamin B12, as well as pancreatic pseudocysts --> presents with steatorrhea, fat-soluble vitamin deficiency, and diabetes mellitus --> diagnosis: low duodenal bicarbonate, low duodenal pH, low fecal elastase --> complication: pancreatic adenocarcinoma)

Patient with history of alcoholism presents with epigastric tenderness, voluminious diarrhea with foul-smelling stool, excretion of fecal fat

Mesenteric venous thrombosis (occurs due to portal hypertension from cirrhosis, aka irreversible liver injury due to chronic injury to resulting in distortion of hepatocyte vascular bed, leading to formation of disorganized regenerative nodules --> portal HTN: increased pressure in portal venous system aka hepatic portal vein/splenic vein + SMV/IMV --> presents with ascites, splenomegaly, esophageal varices, caput medusae, hemorrhoids, portal/splenic/mesenteric vein thrombi)

Patient with history of cirrhosis and HCC presents with acute onset of abdominal pain/tenderness, nausea, vomiting, bloody diarrhea, rigid abdominal wall with loss of bowel sounds, half of small intestine appears dark purple-red with hemorrhagic appearance

Orbital floor fracture (occurs due to blunt trauma to eye --> thin-walled orbital floor composed of zygomatic bone and maxilla --> infraorbital nerve, aka branch of maxillary nerve/CNV2 , runs along orbital surface of maxilla and exits skull just below orbit via infraorbital foramen, thus highly susceptible to damage --> orbital floor fracture also causes herniation of contents into maxillary sinus, resulting in enophthalmus and entrapment of IR muscle resulting in impaired vertical gaze --> presents with numbness and paresthesia of upper cheek/lip/gingiva, enophthalmos, vertical diplopia)

Patient with history of eye trauma presents with diplopia, periorbital ecchymosis, enopthalmos, limited vertical movement of right eye, reduced sensation of upper cheek/lip/gingiva

Vibrio vulnificus (curved gram-negative rod that lives in brackish coastal water and salt water --> transmitted via consumption of raw oysters or wound contamination during recreational water activities/handling of raw seafood --> HIGH RISK of infection in patients with pre-existing liver disease such as cirrhosis/hepatitis or hemochromatosis --> present initially with mild cellulitis, but can develop rapidly progressive necrotizing fasciitis with hemorrhagic bullae and septic shock --> treatment: urgent antibiotics + surgery + BP support)

Patient with history of hemochromatosis went boating recently and had mild cellulitis on his leg, now presenting with a necrotic ulcer with hemorrhagic bullous lesions, fever, hypotension, tachycardia, elevated WBCs and lactic acid

Lacunar infarct (ischemic stroke involving small penetrating lenticulostriate arteries that supply deep brain structures such as basal ganglia/pons, as well as subcortical white matter such as internal capsule and corona radiata --> caused by chronic uncontrolled hypertension, which promotes hyaline arteriolosclerosis and hardening/thickening of vessel wall --> leads to progressive narrowing of arteriolar lumen and eventual thrombotic vessel occlusion --> if occurs in POSTERIOR limb of internal capsule/basal pons, presents with pure MOTOR hemiparesis and/or ataxia-hemiplegia syndrome --> if occurs in GENU of internal capsule/basal pons, presents with dysarthria-clumsy hand syndrome --> if occurs in VPL or VPM nuclei of thalamus, presents with pure SENSORY stroke --> although initial CT scan will not show abnormalities due to small infarct size, a delayed CT scan 4wks layer will show lacunas-- aka CSF-filled cavitary lesion surrounded by scar tissue--due to liquefactive necrosis)

Patient with history of hypertension presents with acute onset of unilateral muscle weakness and decreased strength (3/5), intact cranial nerves/sensory function, CT scan shows no abnormalities

Hypertensive emergency (malignant hypertension: severe hypertension with BP >200/120 that causes hyperplastic arteriolosclerosis of small arteries/arterioles --> results in FIBRINOID NECROSIS of blood vessel wall, causing acute end-organ ischemia --> classically presents with acute renal failure + headache + papilledema due to elevated ICP --> also associated with encephalopathy/stroke, flame-shaped retinal hemorrhages with macular star exudate, acute MI and/or heart failure, aortic dissection, MAHA --> gross kidney will show "flea-bitten" appearance with pinpoint hemorrhages --> treat with nitroprusside, Ca2+ channel blockers such as clevidipine or nicardipine, D1 agonist aka fenoldopam, labetalol, or clonidine)

Patient with history of hypertension presents with headache, papilledema, oliguria, and elevated BUN and creatinine

Enterococcus endocarditis (subacute bacterial endocarditis caused by Enterococcus faecalis/faecium: catalase-negative, gamma-hemolytic, PYR-positive, gram-positive cocci that grows in 6.5% NaCl and bile --> part of normal colonic flora --> often associated with subacute endocarditis on previously damaged valves following GI/GU procedures --> also associated with UTIs and biliary tract infections --> inherently penicillin resistant, and vancomycin-resistant enterococci/VRE important cause of nosocomial infection --> treat sensitive enterococci with ceftaroline --> treat VRE with linezolid, daptomycin, or tigecycline)

Patient with history of mitral valve prolapse recently underwent GI/GU surgery and now presents with low-grade fever, round white spots on retina surrounded by hemorrhage, tender raised lesions on fingers/toe pads, splinter hemorrhages on nail bed, and small painless erythematous lesions on palms and soles

Lhermitte phenomenon (occurs in patients with MS: type of spinal cord syndrome that causes electric shock-like sensation along cervical spine on neck flexion --> associated with other spinal cord syndromes such as neurogenic bladder, paraparesis, and sensory manifestations affecting trunk or 1+ extremity)

Patient with history of multiple sclerosis presents with electric shock-like sensation near the back of the neck when bending neck

Baker cyst (popliteal cyst: occurs due to extrusion of excess synovial fluid into gastrocnemius-semimembranous bursa, which is located in popliteal fossa --> MRI of knee shows popliteal fluid collection POSTERIOR to medial femoral condyle --> associated with chronic joint disease such as rheumatoid arthritis, osteoarthritis

Patient with history of osteoarthritis presents with swelling in popliteal fossa

Chronic struvite stone (aka chronic staghorn calculus: occurs due to recurrent UTIs with urease-positive organisms such as Proteus, S. saprophyticus, Klebsiella that hydrolyze urea into ammonia/NH3 --> NH3 increases pH of urine, facilitating precipitation of ammonium Mg2+ phosphate/AMP/struvite stones --> grow rapidly into branched staghorn calculus that fills renal calyces/pelvis, but does NOT pass into ureter/cause acute obstruction due to large size --> eventually chronic infection and obstructive nephropathy results in kidney atrophy --> presents with recurrent UTIs, fever, mild flank pain, decreased urine output --> CT shows atrophy of renal parenchyma --> treat with antibiotics and surgical removal of stone)

Patient with history of recurrent UTIs presents with left flank pain, hematuria, CT scan shows unilateral kidney atrophy

Budd-Chiari syndrome (thrombosis/compression of hepatic vein that causes centrilobular congestion and necrosis of liver --> results in increased intrahepatic pressure and congestive liver disease --> associated with hypercoagulable states such as antiphospholipid syndrome/factor V leiden/OCP use, polycyhtemia vera that can be idiopathic or 2° from RCC, post-partum, or cirrhosis/hepatocellular carcinoma --> presents with hepatomegaly, ascites, esophageal varices, abdominal pain, liver failure, ABSENCE OF JVD --> gross liver appears enlarged with tense capsule and reddish-purple parenchyma, aka "nutmeg liver" with mottled appearance --> liver biopsy shows centrilobular congestion and necrosis)

Patient with history of renal cell carcinoma presents with mildly increased total bilirubin/AlkPhos/AST/ALT, CT scan of abdomen shows widened hepatic venules

Leukocytoclastic vasculitis (cutaneous small vessel vasculitis: SKIN-ONLY vasculitis associated with hepatitis C, penicillins, cephalosporins, sulfonamides, phenytoin, allopurinol --> forms non-blanching palpable purpura on skin, usually involving lower extremities --> skin biopsy shows inflamed small blood vessels/perivascular inflammation with fibrinoid necrosis, neutrophil and fragmented neutrophilic nuclei within first 24hrs, and monocytes in older lesions)

Patient with history of sore throat treated with penicillin presents with several violaceous, raised, non-blanchable lesions distributed over bilateral lower extremities

Uncal herniation (occurs due to acute hematoma in medial temporal lobe, resulting in increased ICP and transtentorial herniation of uncus --> causes compression of IPSILATERAL CN3 as it exits midbrain at same level as uncus, damaging the somatic motor and PSNS fibers running within CN3 --> presents with headache, impaired consciousness, Cushing triad of HTN + bradycardia + low RR, ipsilateral CN3 palsy with ptosis and "down and out" gaze, and ipsilateral fixed dilated pupil --> as herniation progresses, damage to midbrain can cause bilateral mid-positioned and fixed pupils, loss of vesitublar-ocular reflexes, and decorticate posturing followed by decerebrate posturing)

Patient with history of temporal lobe hemorrhage presents with decreased consciousness, tonic-clonic seizures, hypertension, bradycardia, low RR with brief episodes of apnea, unilateral blown pupil

Angiodysplasia (acquired malformation of mucosal and submucosal capillary beds, associated with aortic stenosis and von Willebrand disease --> high wall stress in RIGHT COLON causes tortuous dilation of vessels, usually in CECUM --> presents in OLDER PATIENTS with hematochezia --> differentiate from colonic diverticula, which usually arises from LEFT/SIGMOID colon)

Patient with history of von Willebrand disease presents with hematochezia

Avascular necrosis of femoral head (osteonecrosis: bone infarction/death of bone and marrow space due to impaired blood supply or vascular insufficiency --> in femoral head of hip, caused by disruption of medial circumflex femoral artery --> associated with CASTS Bend Legs: corticosteroids, alcoholism, sickle cell disease, trauma, SLE vasculitis, the "bends" aka caisson/decompression sickness or fat emboli, Legg-Calve-Perthes disease, Gaucher disease, slipped capital femoral epiphysis --> presents with chronic progressive groin/hip pain exacerbated by weight bearing, restricted movement in affected joint, ABSENCE of swelling/erythema/warmth in surrounding area --> gross femoral head shows subchondral osteonecrosis with wedge-shaped infarct and intact cartilaginous surface --> biopsy shows dead bony trabeculae/empty lacunae with empty marrow space and fat necrosis of surrounding adipocytes --> complications: osteoarthritis and joint replacement)

Patient with left hip and pelvic pain that is constant/dull/achy at rest and exacerbated by movement of hip or weight bearing, decreased passive rotation/extension/abduction at hip, no redness or warmth over hip joint

Trochlear nerve palsy (CN4 damage, usually due to head injury: exits brainstem on DORSAL side and winds around brainstem to pass into lateral wall of cavernous sinus --> innervates CONTRALATERAL SO muscle, which depresses eye --> damage to CN4 causes affected eye to drift UPWARD due to the unopposed actions of the remaining extraocular muscles --> causes vertical diplopia when trying to look down --> to compensate, patients tilt head forward/tuck chin in to bring visual fields back together)

Patient with long-standing forward head tilt presents with diplopia when trying to look down, one pupil higher than the other

IVC obstruction (usually associated with renal cell carcinoma/RCC extending into IVC lumen causing thrombus, OR mass effect from tumor itself --> inhibition of venous flow causes edema of lower extremities BILATERALLY --> also associated with collateral venous circulation, usually prominent abdominal wall collateral veins --> presents in patients with HISTORY OF RCC with bilateral pitting edema of lower extremities and prominent veins on lower abdominal wall)

Patient with mobile left flank mass, symmetric pitting edema of lower extremities, and vertically-oriented tortuous veins on lower abdominal wall

Small intestinal bacterial overgrowth (SIBO: colonization of SMALL intestine, which normally has few GI flora, with colonic bacteria --> associated with stomach/duodenal surgery and formation of blind loop, celiac disease/scleroderma that causes diffuse slowing of small bowel, chronic pancreatitis, immunosuppression --> presents with nausea, bloating, flatulence, abdominal discomfort/pain, steatorrhea, weight loss, possible anemia from decreased iron or folate/vitamin B12 absorption --> diagnosis: decreased D-xylose test, indicating defect in small intestinal mucosa --> treat with rifaximin or neomycin, which destroy NH3-producing gut bacteria)

Patient with nausea, bloating, abdominal discomfort, flatulence, steatorrhea

NF1 (neurofibromatosis type 1: autosomal dominant disorder due to mutation in neurofibromin/NF1 gene on chromosome 17, which is a negative RAS regulator --> causes formation of neurofibromas with skin/deeper tissue, and consist of loose disorganized proliferations of SCHWANN CELLS/fibroblasts/neurites --> presents with cafe-au-lait macules, intellectual disability, cutaneous neurofibromas, Lisch nodules aka pigmented iris hamartomas, axillary freckling/Crowe sign, bone lesions such as sphenoid dysplasia --> INCREASED RISK of CNS/neuroendocrine tumors such as optic gliomas, pilocystic astrocytomas, meningiomas, pheochromocytomas, GI stromal tumors)

Patient with numerous flesh-colored skin nodules on neck and back, pigmented lesions at inner aspect of arm/axilla/trunk, mild scoliosis and low back pain

Acute respiratory distress syndrome (caused by acute alveolar injury from sepsis, aspiration, pneumonia, trauma, pancreatitis --> causes release of pro-inflammatory cytokines that recruit neutrophils and cause release of toxic mediators such as ROS/proteases --> diffuse damage to capillary endothelium, causing increased vessel permeability and leakage of protein-rich fluid into alveoli --> causes formation of intra-alveolar hyaline membranes and loss of surfactant, which impair gas exchange and decrease lung compliance --> resulting in non-cardiogenic pulmonary edema, pulmonary HTN, and alveolar collapse --> presents with respiratory failure symptoms with NORMAL PCWP, hypoxemia with cyanosis, and low PaO2/FiO2 ratio <300 due to intrapulmonary shunting and diffusion problems --> lung biopsy shows alveolar ducts lined with hyaline membranes --> CXR shows diffuse bilateral lung opacities --> treat underlying cause, and provide mechanical ventilation with low TV and high PEEP)

Patient with pneumonia presents with acute onset of cough, dyspnea, hyperventilation, bluish skin discoloration, diffuse crackles

Pleural empyema (bacterial infection of pleural space, usually due to associated pneumonia --> most commonly caused by S. aureus, which forms superimposed secondary pneumonia on top of viral upper respiratory infection)

Patient with pneumonia presents with fever, cough, shortness of breath, chills, CXR shows pleural effusion, pleural fluid aspirate shows thick fibrinous exudate and pus

Chronic vitamin A toxicity (occurs after long-term ingestion of high doses of vitamin A --> presents with alopecia, dry skin, hyperlipidemia, hepatotoxicity, hepatosplenomegaly, and visual difficulties --> can also cause pseudotomor cerebri, aka elevated ICP with no obvious cause, that presents with headache, tinnitus, diplopia, papilledema, visual field testing shows enlarged blind spot and peripheral constriction --> treat with CA inhibitor acetazolamide)

Patient with psychiatric illness and abnormal diet presents with headaches, vomiting, papilledema, dry skin, and hepatosplenomegaly

Pancreatic abscess

Patient with recent bout of acute pancreatitis presents with fever, abdominal pain, and persistently elevated serum amylase

Fulminant hepatitis (extensive hepatocellular damage --> associated with HEV in pregnant women, Vibrio vulnificus in patients with pre-existing liver disease, and halothane hepatotoxicity during anesthesia --> gross liver appears shrunken with severe atrophy --> liver biopsy shows widespread centrilobular necrosis and inflammation of portal tracts/parenchyma --> patients present with fever, anorexia, nausea, myalgia, arthralgia, rash, tender hepatomegaly, jaundice --> lab findings: elevated AST and ALT, prolonged PT, leukocytosis, eosinophilia --> NOTE: only indication of liver damage is PROLONGED PT due to short half-life of factor 7, so despite acute onset there is still enough time for factor 7 depletion)

Patient with recent surgery presents with

Rhabdomyolysis (myocyte injury/necrosis resulting in release of intracellular muscle contents into circulation such as myoglobin, CK, K+, phosphate, uric acid --> associated with crush injuries, prolonged muscle activity due to seizures or marathon running, and drug reactions with statins/fibrates, niacin, colchicine, daptomycin, IFN-alpha, penicillamine, steroids, amphetamines, heroin --> release of myoglobin into circulation causes kidney to filter and degrade myoglobin in glomeruli --> releases heme pigment, which causes free radical injury and acute tubular necrosis --> presents with renal failure, hyperkalemia, and urinalysis with 3+ blood but no RBC casts --> urine dipstick: detects blood due to reaction with heme pigment in myoglobin but NO RBC casts, indicating myoglobinuria --> lab findings: ↑CK, ↑K+, ↑phosphate, ↑uric acid due to myocyte lysis)

Patient with repeated prolonged tonic-clonic seizures presents with low urine output and elevated BUN/Cr, bibasilar lung crackles, mild edema of lower extremities, hyperkalemia, proteinuria and hematuria but NO RBC casts

ARDS (acute respiratory distress syndrome: bilateral pulmonary infiltrates in the absence of heart failure caused by damage to alveolar-capillary interface --> associated with direct pulmonary trauma such as contusions/inhaled irritants, or indirect non-pulmonary insults that can cause epithelial and/or endothelial injury such as sepsis, burns, pancreatitis, DIC --> FIRST exudative phase associated with TNF/IL-1/IL-6 activating pulmonary endothelium and recruiting neutrophils to lung tissue, causing endothelial damage and increased capillary permeability with leakage of protein-rich fluid into alveolar space and formation of hyaline membranes --> presents with non-cardiogenic pulmonary edema with fluid transudation into alveolar spaces --> SECOND proliferative phase occurs 1-2wks later with endothelial cells/pneumocytes/fibroblasts proliferating in attempt to repair damaged lung, but if serious damage to type 2 pneumocytes then fibrosis/scarring occurs --> FINAL fibrotic phase associated with excessive collagen deposition leading to irreversible pulmonary fibrosis and pulmonary HTN --> treat underlying mechanical cause + mechanical ventilation with low TV and high PEEP)

Patient with sepsis presents with hypoxia

Aortic stenosis (causes pulsus parvus/small pulse amplitude and pulsus tardus/slower upstroke of arterial pulse --> due to diminished stroke volume and prolonged ejection time from diminished aortic valve lumen)

Patient with small pulse amplitude with delayed peak and slower upstroke of arterial pulse

Non-small cell lung cancer (NSCLC: approximately 4% of patients have inversion of chromosome 2 short arm --> creates fusion gene between EML4 and ALK genes, forming constitutively active tyrosine kinase fusion protein EML4-ALK --> usually causes lung adenocarcinoma in YOUNG NON-SMOKERS who lack mutations in EGFR or KRAS --> treat with crizotinib, which targets specific EML4-ALK fusion protein)

Patients positive for EML4-ALK fusion protein

Basophilic stippling (RBCs with aggregates of residual ribosomes within cytoplasm --> associated with sideroblastic anemia due to X-linked ALAS deficiency, alcohol abuse, lead poisoning, vitamin B6 deficiency from isoniazid use --> also associated with beta-thalassemia)

Peripheral smear shows RBCs with blue granules dispersed within cytosol

Target cells (occur in RBCs with high surface area-to-volume ratio due to excess membrane blebs in middle of RBCs, allowing it to be LESS susceptible to osmotic stress --> associated with reduced RBC volume from deficient Hb synthesis such as beta-thalassemia/iron deficiency, OR from structurally mutated Hb such as sickle cell disease or HbC disease --> associated with excessive RBC membrane due to splenectomy, which prevents splenic pruning of RBCs --> ALSO associated with obstructive liver disease, which causes greater cholesterol-to-phospholipid ratios resulting in excessive RBC cell membrane)

Peripheral smear shows RBCs with dark center, a surrounding halo of pallor, and a dark peripheral ring

Acanthocytes (spur cells: associated with conditions of cholesterol dysregulation --> seen in abetalipoproteinemia, liver disease, and vitamin E deficiency)

Peripheral smear shows RBCs with large asymmetric spikes

Bite cells (RBCs with large portions of membrane missing due to splenic macrophage removal of Heinz bodies, aka denatured/precipitated oxidized Hb --> associated with G6PD deficiency)

Peripheral smear shows RBCs with missing semicircular portions

Howell-Jolly bodies (clusters of DNA remnants within RBCs --> associated with splenectomy or hyposplenism in sickle cell disease, as spleen usually removes these DNA remnants)

Peripheral smear shows RBCs with peripheral round blue/purple inclusions

Spherocytes (RBCs with low surface area-to-volume ratio due to loss of membrane pieces by spleen --> associated with hereditary spherocytosis and autoimmune hemolytic anemia --> causes RBCs to be MORE susceptible to osmotic stress)

Peripheral smear shows dense round RBCs without central pallor

Bernard-Soulier syndrome (QUALITATIVE platelet disorder: defect in Gp1b results in defective platelet-to-vWF adhesion, causing defective platelet plug formation --> presents with bleeding gums, epistaxis, heavy periods, perioperative and post-op bleeding, NO PETECHIAE due to normal platelet count --> peripheral smear shows enlarged platelets with mild thrombocytopenia --> diagnosis: abnormal ristocetin test that DOES NOT correct with mixing studies --> lab findings: NORMAL platelet count and ↑bleeding time)

Peripheral smear shows enlarged platelets, with mildly low platelet count

Echinocytes (burr cells: associated with pyruvate kinase deficiency, which decreases ATP to form rigid RBCs that cause extravascular hemolysis --> ALSO associated with end-stage renal disease and liver disease)

Peripheral smear shows small uniform "spiky" projections

Dacrocytes (teardrop cells: RBCs are elongated due to being mechanically squeezed out of bone marrow and/or extramedullary hematopoietic sites --> associated with myelofibrosis and beta-thalassemia major)

Peripheral smear shows teardrop-shaped RBCs

Pappenheimer bodies (aggregated iron deposits in RBCs --> associated with sideroblastic anemia caused by X-linked ALAS deficiency, alcoholism, lead poisoning, or vitamin B6 deficiency from isoniazid use)

Peripheral smear stained with Prussian blue shows RBCs with dark blue inclusions

Acoustic Schwannoma (acoustic neuroma: arises from Schwann cells from within CN8, which exits brainstem from pontomedullary junction LATERAL TO CN7 and enters cerebellopontine angle --> present with IPSILATERAL sensorineural hearing loss and tinitus due to damage to cochlear part --> damage to vestibular part can result in vertigo, dysequilibrium, and nystagmus --> unilateral Schwannomas are usually sporadic, while bilateral Schwannomas associated with NF2)

Persistent buzzing in one year with decreased hearing, MRI shows intracranial tumor

Mesothelioma (rare malignant neoplasm arising from mesothelial cells, which line the pleura --> associated with asbestos exposure from mining, shipbuilding, insulation/house construction --> presents with recurrent hemorrhagic pleural effusions --> CXR/CT shows smooth unilateral pleural thickening with pleural plaques --> biopsy shows abundant tonofilaments, very long microvilli, and Psammoma bodies --> diagnosis: positive for calretinin)

Pleural biopsy shows proliferation of epithelioid-type cells joined by desmosomes, abundant tonofilaments, very long microvillli, laminated concentric calcifications

Hemochromatosis and liver disease (ex: alcoholic cirrhosis, hepatitis, non-alcoholic fatty liver disease --> V. vulnificus is curved gram-negative rod found in salt water/brackish water --> transmitted via raw oysters or wound contamination from water activities --> usually presents with mild cellulitis, but in patients with liver disease can cause rapidly progressive necrotizing fasciitis with hemorrhagic bullae lesions and septic shock)

Populations at risk for necrotizing fasciitis caused by V. vulnificus

Colorectal cancer (causes occult blood loss --> usually presents with iron-deficiency anemia due to continuous loss of blood in stool --> blood loss is usually OCCULT, thus causing absence of dark/bright red stools --> diagnosis: iron studies and endoscopy)

Postmenopausal woman with normal diet presents with progressive fatigue, heart palpitations, low Hb, peripheral smear shows pale microcytes,

Vasa previa (fetal vessels run over or are in close proximity to cervical os --> causes velamentous umbilical cord insertion, aka cord inserts onto chorioamniotic membrane rather than placenta, causing fetal vessels to travel to placenta UNPROTECTED by Wharton jelly --> may result in vessel rupture, fetal exsanguination, or feta death --> usually presents with TRIAD of ruptured membranes + painless vaginal bleeding + fetal bradycardia --> treatment is emergency C-section)

Pregnant mother presents with rupture of membranes and painless vaginal bleeding, fetal heart tracing indicates bradycardia

Neonatal HBV (occurs due to mother-to-child transmission during DELIVERY --> associated with maternal viral load and positive HBeAG, the latter has >90% chance of infant acquiring HBV infection --> infants initially present with immune-tolerant phase in which they are asymptomatic, due to immature T cells limiting hepatocyte damage --> over time, newborns develop chronic HBV and can progress to cirrhosis and HCC --> lab findings: positive HBsAg and HBeAg --> prevention: HBV vaccine and IVIG to newborn ASAP after delivery --> should monitor with serology 3months after 3rd dose of vaccine)

Pregnant mother with (+)HBsAg, (+)HBeAg, (+)anti-HBc, (-)anti-HBs

Polyhydramnios (too much amniotic fluid: can be idiopathic or associated with fetal malformations such as esophageal/duodenal atresia or anencephaly with inability of fetus to swallow amniotic fluid --> can also be associated with maternal diabetes, fetal anemia, or multiple gestations)

Pregnant mother with greater-than-expected fundal height and increased amniotic fluid

Neonatal ITP (neonatal immune thrombocytopenia: occurs due to placental transfer of maternal auto-antibodies against Gp2b/3a to fetus --> maternal auto-antibodies decrease # of platelets in newborn, causing mucus membrane bleeding and petechiae --> SHORT-LIVED and will resolve once newborn produces its own IgG and maternal antibody levels go down --> can treat severe symptomatic bleeding with IVIG)

Pregnant mother with history of SLE gives birth to a newborn with thrombocytopenia

Listeria monocytogenes (facultative anaerobic, intracellular, gram-positive rod that produces very narrow zone of beta hemolysis on blood agar --> characterized by "rocket tails" via actin polyermization that allow intracellular movement between cells to avoid antibody --> has tumbling motility with flagella seen at room temp but not body temp --> multiplies in cold temp/"cold enrichment" which allows it to be transmitted via unpasteurized dairy products, cold deli meats, transplacenta, vaginal during delivery --> causes septicemia/amnionitis/spontaneous abortion in pregnant women, neonatal meningitis, meningitis in immunocompromised, and gastroenteritis in healthy individuals --> grows within macrophages, thus eliminated via cell-mediated immunity due to infected macrophages displaying MHCI that triggers CD8+ T cells to lyse infected macrophage and release IFNy --> releases Listeria into extracellular space, where it can be phagocytized by IFNy-activated macrophages --> treat with ampicillin)

Pregnant woman with fever, chills, muscle aches, hypotension, tachycardia, elevated WBCs

HELLP syndrome (hemolysis, elevated liver enzymes, low platelets syndrome: seen in PREGNANT WOMEN as a manifestation of severe eclampsia --> caused by abnormal placental spiral arteries leading to endothelial dysfunction, vasoconstriction, and ischemia --> initially presents as pre-eclampsia with hypertension and proteinuria --> can later present with eclampsia with maternal seizures --> finally presents with HELLP with microangiopathic hemolytic anemia and schistocytes --> complication: DIC and hepatic subscapular hematoma, which can rupture and cause severe hypotension --> treat with immediate delivery)

Pregnant woman with nausea, vomiting, hypertension, abdominal pain with RUQ tenderness, low Hb, low HCT, low platelets, elevated total bilirubin, elevated ALT and AST

Familial dysbetalipoproteinemia (type III hyperlipoproteinemia: autosomal RECESSIVE defect in ApoE, which mediates uptake of all remnants except LDL --> elevated levels of chylomicrons and VLDL remnants --> presents with premature atherosclerosis and tuberoeruptive palmar xanthomas)

Premature coronary artery disease and peripheral vascular disease, tuberoeruptive and palmar xanthomas

Familial hypercholesterolemia (type IIa hyperlipoproteinemia: autosomal DOMINANT defect in LDL receptors or ApoB100, which helps to bind LDL receptor on VLDL/IDL/LDL --> elevated levels of LDL --> heterozygotes have cholesterol ~300 while homozygous have cholesterol >700 --> present with accelerated atherosclerosis with MI before age 20, tendon/Achilles xanthomas, and corneal arcus)

Premature coronary artery disease, corneal arcus, tendon xanthomas, xanthelasmas

Pancreatic adenocarcinoma (arises from pancreatic ducts, associated with SMOKING/chronic pancreatitis/diabetes/Jewish and African-American males --> very aggressive tumor and often metastatic at presentation, <1yr average survival --> associated with CA 19-9 tumor marker --> presents with weight loss/anorexia due to malabsorption, obstructive jaundice, Courvoisier sign/palpable non-tender bladder, Trousseau syndrome/redness and tenderness on palpation of extremities, and abdominal pain radiating to back/ascites if metastatic --> treat with Whipple procedure/pancreatico-duodenectomy + chemotherapy + radiation therapy)

Progressive weight loss and anorexia, jaundice, dark urine and pale stools, enlarged but non-tender gallbladder

Complicated grief (persistent complex bereavement disorder: prolonged grief for >12 months, difficulty accepting death, persistent yearning for decreased, and inability to reengage with life)

Prolonged grief for >12 months with difficulty accepting death and inability to reengage with life

Familial chylomicronemia syndrome (type 1 hyperlipoproteinemia: autosomal RECESSIVE defect in lipoprotein lipase or ApoC-II, which serves as a cofactor for lipoprotein lipase --> elevated levels of chylomicrons, TGs, and cholesterol--> presents with pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas with creamy layer in supernatant, and NO risk of atherosclerosis)

Recurrent bouts of acute pancreatitis, lipemia retinalis, eruptive skin xanthomas, hepatosplenomegaly

Familial triglyceridemia (type IV hyperlipoproteinemia: autosomal DOMINANT defect that causes hepatic overproduction of VLDL --> elevated levels of VLDL and TGs --> presents with TGs >1000 and increased risk of pancreatitis)

Recurrent pancreatitis, obesity, insulin resistance

Selective IgA deficiency (most common immunodeficiency --> mostly asymptomatic --> form IgE antibodies against IgA, which causes fatal anaphylaxis during transfusion with blood products --> presents with facial swelling, generalized hives, dyspnea upon blood transfusion)

Recurrent sinusitis/pneumonia and Giardia infections, celiac disease, anaphylaxis during blood transfusions

Acute tubular necrosis (ATN: can be caused by ischemia/decreased renal perfusion due to hypotension/cardiogenic shock/sepsis/ hemorrhage/HF --> can also be caused by direct toxic injury by cyclosporine/ tacrolimus/aminoglycosides/ radiocontrast agents/lead/ cisplatin/myoglobinuria/ hemoglobinuria --> PCT is most susceptible to both types of injury, while thick ascending limb is also susceptible to ischemia --> initiation phase in first 24-46hrs only presents with slight decrease in urine output --> maintenance phase occurs from day 3 - 2wks after insult and characterized by fully established tubular damage and low GFR, presents with elevated serum creatinine, oliguria, BUN/Cr <20, and muddy brown granular casts in urine --> recovery phase occurs 3wks later and characterized by re-epithelization of tubules, recovery of GFR, but transient polyuria/loss of electrolytes due to impaired tubular reabsorption and decreased renal concentrating ability)

Renal biopsy shows patchy necrosis PCT epithelial cells with epithelial vacuolization, interstitial edema, and denudation of tubular basement membrane

Analgesic nephropathy (chronic interstitial nephritis due to long-term NSAID use: seen in patients on high-dose NSAIDs for chronic pain, such as patients with back pain who take naproxen daily --> NSAIDs concentrate in renal medulla along medullary osmotic gradient with higher levels in papillae --> uncouple oxidative phosphorylation, causing glutathione depletion and free radical injury --> lipid peroxidation causes fibrosis/atrophy of tubular and vascular endothelial cells --> also decreases PG synthesis in afferent arterioles, causing constriction of medullary vasa recta and ischemic papillary necrosis that can develop calcifications --> presents with mildly elevated creatinine, mild proteinuria and sterile pyuria, evidence of tubular dysfunction such as edema/polyuria/nocturia, and possible distal renal tubular acidosis/type 1 RTA with low H+ secretion/alkaline urine --> kidney biopsy shows patchy interstitial inflammation with fibrosis, tubular atrophy, papillary necrosis/scarring, and architectural distortion of calyces --> treat with cessation of NSAID use)

Renal ultrasound shows bilateral shrunken and irregular kidneys with few papillary calcifications

Pinworm

Scotch tape test shows oval, asymmetrically flattened eggs with bean-shaped appearance

L3-L4 herniated disc (affects L 4 nerve root: paresthesia and weakness of anterior thigh/knee and medial leg due to L3-L4 IV disc/nucleus pulposus herniating posterolaterally through annulus fibrosis/outer ring into central canal --> occurs as a result of THIN posterior longitudinal ligament and THICK anterior longitudinal ligament along midline of vertebral bodies)

Severe pain in lower back that radiates down anterior thigh/knee and medial leg/foot with weakness of knee extension and decreased patellar reflex

L3-L4 herniated disc (affects L 4 nerve root: paresthesia and weakness of anterior thigh/knee and medial leg due to L3-L4 IV disc/nucleus pulposus herniating posterolaterally through annulus fibrosis/outer ring into central canal --> occurs as a result of THIN posterior longitudinal ligament and THICK anterior longitudinal ligament along midline of vertebral bodies --> presents with pain and paresthesia along anterior thigh/anterior knee/medial leg/medial foot with weakness of knee extension and decreased patellar reflex)

Severe pain in lower back that radiates down anterior thigh/knee, medial leg, and medial foot

Trochanteric bursitis (inflammation of gluteal tendon and bursa LATERAL to greater trochanter of femur --> presents with sharp intermittent pain at lateral hip/thigh, increased pain when putting on affected hip and with walking, normal joint movement --> treat with NSAIDs, heat, stretching)

Sharp intermittent pain at lateral hip and thigh, increased pain with lying on affected side and with walking, normal joint movement

Intradermal nevus (considered "older" lesions in which epidermal nests of nevus cells have been lost, therefore nevus aggregates only remain in dermis --> dermal nevus cells lose tyrosinase activity and produce little to no pigment --> appear as skin- to tan-colored, dome-shaped, and sometimes pedunculated lesions)

Skin biopsy shows aggregates of nevus cells located exclusively within dermis

Junctional nevus (characterized by aggregates of nevus cells LIMITED to basal portion of epidermis without invasion into dermis --> appears as a FLAT, black-to-brown pigmented macule with darker coloration in CENTER and preserved skin markings)

Skin biopsy shows aggregates of uniform round cells limited to dermoepidermal junction (NO invasion into dermis)

Neurofibroma (excessive proliferation of Schwann cells within the DERMIS --> usually associated with NF1, caused by NF1 gene mutation on chromosome 17 --> biopsy shows dermal nodule containing spindle cells with wavy nuclei and intense pink stroma)

Skin biopsy shows elongated spindle-shaped cells with wavy/serpiginous nuclei, fibroblasts, and neurites

Compound nevus (formed as aggregates of nevus cells extend into dermis --> appear as RAISED papule with uniform brown to tan pigmentation

Skin biopsy shows nests of uniform round cells at basal portion of epidermis that extend into underlying dermis

Melanoma (malignant skin cancer arising from melanocytes, significant risk of metastasis: associated with prolonged UV-B exposure, albinism, xeroderma pigmentosum, and dysplastic nevus syndrome --> presents with a mole that is asymmetric, irregular borders, color variation, diameter >6mm, and increasing in size --> often associated with mutations that activate BRAF kinase --> note: depth of tumor/Breslow thickness correlates with risk of metastasis --> treatment: excision with wide margins, and vemurafenib for patients with BRAF V600E mutation)

Skin biopsy shows pleomorphic hyperchromatic cells within clear islands that tend to coalesce and are present at all levels of epidermis, extension into papillary dermis

Verruca vulgaris (common warts: caused by HPV-1 to HPV-4 --> transmitted via direct contact --> cause skin lesions typically on the found on the hands/feet,NO cancerous potential --> skin biopsy shows epidermal hyperplasia, hyperkeratosis, and koilocytosis)

Soft, tan-colored, cauliflower-like papules on hands and feet

Dysentery (inflammatory diarrhea: caused by pathogens that INVADE intestinal epithelium and/or produce cytotoxins resulting in cell death --> associated with C. difficile, Salmonella, Shigella, Campylobacter, Yersinia, EIEC, Entamoeba histolytica --> NOTE: EHEC-related diarrhea causes toxin-mediated enterocyte death WITHOUT mucosal invasion, therefore stool findings show RBCs without leukocytes)

Stool findings: RBCs and many WBCs with neutrophil predominance

Watery diarrhea (non-inflammatory/enterotoxic diarrhea: caused by pathogens that DO NOT invade intestinal epithelium, but rather produce enterotoxin that activates Na+ and/or Cl- secretion to promote movement of water from enterocyte to GI lumen --> associated with S. aureus, Bacillus cereus, C. perfringens, ETEC, V. cholerae, rotavirus, norovirus, enteric adenovirus, Giardia, Cryptosporidium)

Stool findings: flecks of mucus, no leukocytes, no RBCs

Salmonella typhi

Stool findings: many WBCs with monocyte predominance

Toluene toxicity (occurs due to abuse of inhaled glue --> causes damage to cerebellar vermis and other parts of cortex --> presents with truncal ataxia/wide-based cerebellar gait, nystagmus, head tilting, memory loss/confusion, cognitive decline)

Teenage boy with bilateral aching in temples, confusion, memory loss, decline in school performance, slow to answer questions, broad-based ataxic gait

Klinefelter syndrome (47XXY karyotype: sex chromosome aneuploidy due to non-disjunction --> causes atrophied, hyalinized seminferous tubules resulting in dysfunctional Sertoli cells and Leydig cells --> decreased testosterone and inhibin levels results in elevated LH and FSH due to loss of negative feedback --> increases estrogen levels, resulting in gynecomastia --> presents with primary hypogonadism with azospermia, small/firm testes, lack of 2° male characteristics such as deep voice/beard/male-pattern pubic hair --> also associated with gynecomastia and cognitive impairment with learning/socialization difficulties --> lab findings: ↓testosterone, ↑LH, ↑FSH, ↑estrogen --> complications: infertility risk of male breast cancer)

Teenage boy with bilateral gynecomastia, intellectual disability, tall height, small firm testicles

IgA nephropathy (Berger disease: most common cause of glomerulonephritis --> presents in OLDER CHILDREN and YOUNG ADULTS with painless hematuria 5-7 days after URI --> kidney biopsy shows mesangial hypercellularity

Teenage boy with episodic hematuria following a flu-like illness, normal BUN and creatinine, urinalysis shows proteinuria and RBCs

Testicular choriocarcinoma (malignant testicular germ cell tumor arising from syncytiotrophoblast and cytotrophoblast --> secretes beta-hCG, which has an alpha-subunit identical to LH/FSH/TSH --> presents with triad of enlarging testicular mass + gynecomastia + hyperthyroidism --> complication: rapid hematogenous metastasis to lungs and brain)

Teenage boy with gynecomastia, firm rapidly growing testicular mass, heat intolerance, tachycardia, palpitations, fine tremors, elevated hCG

Anabolic steroid use (abuse of anabolic steroids to increase fat-free mass, muscle strength, and performance --> exogenous testosterone inhibits hypothalamus/pituitary from secreting LH and FSH --> Sertoli cells cannot increase local testosterone levels within testes, causing decreased testicular size and decreased spermatogenesis --> presents in men with changes in behavior/more aggressive, acne, gynecomastia, small testes, decreased sperm count/azospermia)

Teenage boy with gynecomastia, small testes, acne, male-pattern baldness, decrease in height curve, aggressive behavior

Osgood-Schlatter disease (traction apophysitis: overuse injury caused by repetitive strain/chronic avulsion of 2° ossification center of proximal tibial tubercle --> usually presents in ADOLESCENTS after growth spurt with progressive anterior knee pain --> associated with running and jumping athletes -->

Teenage boy with progressive anterior knee pain with warmth, swelling, and tenderness, CXR shows fragmentation of tibial tubercle

Tuberculoid leprosy (caused by Mycobacterium leprae: acid-fast bacillus that infects skin and superficial nerves due to affinity for COOL TEMPERATURES --> transmitted via armadillos in USA --> tuberculoid leprosy characterized by a few hypoesthetic hairless skin plaques due to high cell-mediated immunity with Th1 response, low bacterial load so fairly non-communicable --> lepromatous leprosy presents DIFFUSELY over skin with lion-like facies due to low cell-mediated immunity with Th2 response, high bacterial load so highly communicable --> treat tuberculoid form with dapsone and rifampin --> treat lepromatous form with dapsone, rifampin and clofazimine)

Teenage girl from India presents with several hypopigmented lesions on neck with decreased tactile sensation

Exercise induced amenorrhea (functional hypothalamic amenorrhea: severe caloric restriction/ increased energy expenditure/increased cortisol secretion during stress causes diminished adipose tissues stores --> decreased circulating leptin causes functional disruption of pulsatile GnRH secretion and decreased LH/FSH secretion --> results in decreased estrogen secretion and lack of ovulation/menstruation --> associated with eating disorders and "female athlete triad" aka low calorie availability/excess exercise + low bone mineral density + menstrual dysfunction)

Teenage girl who does competitive gymnastics presents with amenorrhea, low body weight, fine hair around trunk

Coarctation of aorta (aortic narrowing near insertion of ductus arteriosus, aka part of aorta just distal to left subclavian artery --> most common cardiac defect in Turner syndrome --> presents with brachial-femoral delay, aka hypertension in upper extremities and weak delayed pulse in lower extremities + enlarged intercostal collateral arteries that erode ribs --> CR shows "notched" appearance of ribs --> complications: heart failure, cerebral hemorrhage due to berry aneurysms, aortic rupture, possible endocarditis)

Teenage girl with Turner syndrome presents with pain/cramping of legs on exertion, pulsatile vessels within intercostal space, diminished femoral pulses relative to brachial pulses

Maturity onset diabetes of the young (MODY: autosomal dominant disorder caused by glucokinase deficiency --> since glucokinase is low-affinity glucose receptor on pancreatic beta cells, glucokinase deficiency causes INCREASED glucose threshold for insulin release --> presents as non-insulin-dependent diabetes in lean young adults with mild hyperglycemia after meals --> NOT associated with elevated risk of long-term diabetes complications --> usually does not require medication and well controlled with dietary modification)

Teenager with family history of diabetes presents with normal BMI, normal fasting blood glucose, elevated 2-hour postprandial glucose

Temporal arteritis (giant cell arteritis: inflammation of carotid artery branches, usually temporal artery, that causes SEGMENTAL granulomatous vasculitis --> seen in ELDERLY FEMALES and associated with polymyalgia rheumatica, which causes flu-like symptoms and achy pain in shoulder and hip girdles --> presents with malaise, headache, jaw/tongue claudication, and visual disturbances such as transient monocular visual loss/blurred vision/ischemic optic neuropathy --> screening: elevated ESR >100 and C-reactive protein --> diagnosis: temporal artery biopsy shows granulomatous inflammation of media with intimal thickening, elastic lamina fragmentation, and multinucleated giant cells --> however, negative biopsy does NOT exclude disease due to segmental vasculitis, aka may have just taken an unaffected segment --> complication: risk of ipsilateral, irreversible blindness due to occlusion of ophthalmic artery -> treat with high-dose glucocorticoids, especially before temporal artery biopsy to prevent blindness)

Temporal artery biopsy shows granulomatous inflammation with multinucleated giant cells, intimal fibrosis, and large separation between intima and media

Complete hydatidiform mole

Ultrasound shows central heterogenous mass in uterus with numerous discrete anechoic spaces

Restless leg syndrome (RLS: urge to move legs while falling asleep, usually seen in middle-aged and older patients --> associated with iron deficiency, CKD, diabetic neuropathy --> associated with dopaminergic pathways --> treat with dopamine agonists such as ropinirole or pramipexole)

Uncomfortable urge to move legs usually during rest/at night, unpleasant sensations in legs, relieved by movement

Hemiballismus (violent flailing movements on one side of body caused by lesion in subthalamic nuclei --> will cause irregular movements on CONTRALATERAL side of body)

Uncontrollable frequent irregular flailing movements on one side of body

Brucellosis (caused by Brucella infection: gram-negative aerobic coccobacillus --> transmitted via ingestion of contaminated animal products such as unpasteurized milk --> bacteria survive in macrophages within reticuloendothelial system, such as spleen --> form non-caseating granulomas)

Undulant fever, night sweats, arthralgia

Cavernous sinus syndrome (increased pressure on cavernous sinus due to pituitary tumor mass effect, carotid-cavernous fistula, cavernous sinus thrombosis due to mucormycosis, or infection that ascended from sinusitis --> impinges on CN3/4/V1/V2/6, internal carotid artery, and SNS pupillary fibers --> presents with opthalmoplegia, decreased corneal sensation, decreased maxillary sensation, proptosis, and Horner syndrome)

Unilateral ophthalmoplegia with weak eye movement, decreased corneal sensation, blown-out pupil, ptosis, anhidrosis, and decreased unilateral maxillary sensation

Carpal tunnel syndrome (compression of medial nerve within carpal tunnel, due to pregnancy, rheumatoid arthritis, hypothyroidis, diabetes, acromegaly, dialysis-related amyloidosis, repetitive use --> carpal tunnel defined by carpal bones DORSALLY and transverse carpal ligament/flexor retinaculum VENTRALLY --> contains median nerve that runs between FDS and FDP muscles, and located VENTRAL to flexor policis longus tendon --> NOTE: loss of thumb opposition BUT thenar sensation remains because palmar cutaneous branch enters hand EXTERNAL to carpal tunnel --> treatment: ligation of transverse carpal ligament)

Unilateral tingling and numbness of hand and index/middle fingers, weakness of thumb opposition, atrophy of thenar eminence

Guyon canal syndrome (compression of ulnar nerve within Guyon canal, usually seen in CYCLISTS due to pressure from handlebars --> ulnar nerve located MEDIAL to ulnar artery and VENTRAL to flexor retinaculum)

Unilateral tingling/numbness of ring and pinky fingers, atrophy of hypothenar eminence

Graves disease (most common cause of hyperthyroidism, usually seen in YOUNG WOMEN --> TSI/thyroid-stimulating Ig stimulates TSH receptors on thyroid gland, causing diffuse goiter and hyperthroid symptoms --> also stimulates TSH on dermal fibroblasts, allowing infiltration by activated T cells and cytokines and resulting in fibroblast secretion of GAGs --> results in osmotic swelling of muscles, muscle inflammation and increased adipocyte count --> presents with diffuse goiter + hyperthyroidism + pretibial myxedema + exophthalmos --> associated with HLA-DR3 and HLA-DR8 --> treat hyperthyroidism with PTU, myxedema/exophthalmos with prednisone)

Thyroid biopsy shows follicular hyperplasia with tall crowded follicular epithelial cells and scalloped colloid

Incarceration and strangulation (incarceration: not reducible back into abdomen/pelvis --> strangulation: ischemia and necrosis of herniated segment --> can present with fever, tenderness, erythema)

Two complications of hernias

Dyslipidemia and smoking (dyslipidemia: increased LDL leads to formation of atherosclerotic plaques --> smoking: tobacco smoke generates free radicals that oxidize LDL and lead to accelerated atherosclerosis, nicotine releases catecholamine resulting in alpha-1 vasoconstriction, and cigarette smoke causes vascular/arteriolar inflammation that induces endothelial cell dysfunction and decreased prostacyclin/NO release causing impaired local vasodilation and increased platelet aggregation)

Two most important risk factors for myocardial infarction

Exogenous thyrotoxicosis (taking thyroid hormone not prescribed for hypothyroidism, usually to lose weight or have increased energy --> presents with symptoms of hyperthyroidism + low TSH + low thyroglobulin + small-sized thyroid with no nodules --> suppressed TSH secretion decreases iodine organification and colloid formation, resulting in thyroid atrophy --> thyroid biopsy would show diffuse atrophy of thyroid follicles with decreased colloid --> diagnosis: LOW THYROGLOBULIN, indicating T4 is exogenous --> NOTE: only the exogenous thyroid hormone will be elevated, aka if patient is taking T4 then labs will show elevated T4 but decreased T3/TSH/thyroglobulin)

Weight loss, tachycardia, anxiety, fine tremor, warm moist skin, elevated T3/T4, low TSH, low thyroglobulin, PE shows small thyroid

Anal sphincter damage (childbirth can cause excess stretching of pudendal nerve/S2-S4 --> injury to pudendal nerve results in decreased sensation in perineum/genital area and fecal/urinary incontinence --> NOTE: pudendal nerve can also be blocked with local anesthetic during childbirth, use ISCHIAL SPINE as landmark for injection)

Woman who gave birth one year ago presents with recurrent fecal incontinence

Rectocele (POSTERIOR prolapse due to protrusion/hernia of rectum into posterior vaginal wall --> associated with tear of rectovaginal septum during CHILDBIRTH or HYSTERECTOMY --> rectal tissue bulges thru the posterior fornix

Woman who recently gave birth presents with bulging of posterior vaginal wall on Valsava maneuver

Amniotic fluid embolism (rare but fatal complication that can occur during pregnancy/shortly after delivery --> amniotic fluid enters maternal circulation via sites of uterine trauma/cervical lacerations ---> causes anaphylactoid reaction, and also travels to pulmonary arteries to cause occlusion/vasospasm of pulmonary circulation resulting in LV failure, decreased CO, and severe V/Q mismatch --> amniotic fluid also contains tissue factor/thromboplastin that triggers DIC --> resultant hypoxia/hypotensive shock can lead to cardiopulmonary arrest --> presents with cardiogenic shock, hypoxemic respiratory failure, DIC, seizures/coma, and eventual cardiopulmoanry arrest --> biopsy of pulmonary arteries will show swirls of fetal squamous cells)

Woman who recently gave birth presents with chest pain, difficulty breathing, hypotension, bradycardia, bleeding at surgical sites, and cardiorespiratory arrest

Maturity onset diabetes of the young (glucokinase heterozygous mutation: prevents activation of pancreatic beta-cells in high glucose states --> cannot produce insulin, therefore glucose remains in vasculature and causes hyperglycemia --> if HETEROZYGOUS, usually presents with mild non-progressive hyperglycemia that worsens with pregnancy-induced insulin resistance --> if HOMOZYGOUS, leads to fetal growth retardation and severe hyperglycemia at birth)

Woman with family history of gestational diabetes presents with modestly elevated hyperglycemia after giving birth

Nocardia infection (aerobic, branching filamentous, partially acid-fast gram-positive rod with some mycolic acids in cell wall --> ubiquitous organism found in soil transmitted from spore inhalation or skin inoculation in patients with traumatic skin lesions --> usually causes cutaneous infection in healthy people, but causes SEVERE bacteremia in patients with impaired cell-mediated immunity such as HIV/transplant --> causes bronchopneumonia with fever/night sweats/fatigue/cough with purulent sputum, CXR shows pulmonary nodules or cavitations --> spreads thru blood and causes multiloculated brain abscesses that present as seizures --> treat with TMP-SMX)

Woman with history of renal transplant and immunosuppression presents with bronchopneumonia and multifocal brain abscesses

Neonatal lupus (caused by placenta transfer of anti-SSA antibody from mother with Sjogren's syndrome to fetus: causes lupus in neonates with congenital HEART BLOCK --> since anti-SSA also seen in subset of SLE patients, need to screen pregnant women with EITHER Sjogren or SLE)

Woman with history of rheumatoid arthritis gives birth to newborn with diffuse rash and petechiae, anemia, and congenital heart block

Intraductal papilloma (small papillary/fibroepithelial growth within lactiferous ducts, classically seen in PRE-MENOPAUSAL women --> caused by proliferation of papillary cells in duct or cyst wall with fibrovascular core --> bloody discharge due to twisting of vascular stalk of papilloma in duct histology shows finger-like projections with fibrovascular core, lined by BOTH luminal epithelial and myoepithelial cells --> 2X increased risk of cancer)

Young adult woman with bloody nipple discharge

Acute decompensated HF (ADHF: occurs with LV systolic or diastolic dysfunction --> increased LA and LV filling pressures transmitted to pulmonary vasculature, causing fluid transudation into lung interstitial/alveolar spaces causing cardiogenic pulmonary edema --> CXR shows prominent pulmonary vessels, patchy bilateral airspace opacities, blunting of costophrenic angles/pleural effusion, and fluid trapped between right upper and middle lobes/fissure sign --> CXR may also cardiomegaly AND/OR show short horizontal lines perpendicular to pleural surface representing edema of interlobular septa/Kerley B lines)

Worsening shortness of breath and cough when lying down, CXR shows prominent pulmonary vessels + pleural effusion + fissure sign

Psoas abscess (psoas muscle originates from ANTERIOR surface of transverse processes/lateral surface of vertebral bodies at T12-L5, then combines with iliacus inferiorly around inferior ligament --> occurs due to direct spread of infection from adjacent structure such as vertebrae/appendix/hip joint OR from hematogenous spread --> associated with diabetes, IV drug use, HIV infection, immunosuppression --> presents with fever, back or flank pain, inguinal mass, difficulty walking, psoas sign aka pain exacerbated during extension of hip, and patients positioned with hip flexion and lumbar lordosis)

Young adult male with history of T1DM presents with fever, back and abdominal pain, weight loss difficulty walking, lies supine with hip flexed, pain on extension of hip and leg

Lyme disease (erythema migrans caused by Borrelia burgdorferi: spirochete found in northeastern USA and northern Europe --> transmitted via Ixodes tick bite --> early localized phase presents with flu-like symptoms and erythema migrans rash with "bulls-eye" configuration --> early disseminated phase seen weeks-months later with secondary skin lesions, AV block, facial nerve palsy, migratory myalgias/transient arthritis --> late Lyme disease seen years later characterized by asymmetric arthritis in single knee joint OR subacute encephalopathy --> treatment includes doxycycline for majority of infections, ceftriaxone for severe illness/CNS signs/heart block)

Young adult male with history of rash and flu-like illness two months ago, now presents with fatigue and pain in multiple joints

Ankylosing spondylitis (seronegative spondyloarthritis associated with HLA-B27: autoimmune destruction of articular cartilage of AXIAL joints, resulting in stiffness and fusion --> usually involves SPINE and SACROILIAC JOINTS, resulting in low back pain that worsens at rest/at night but improves with exercise --> can also involve THORACIC SPINE which limits chest wall expansion and can lead to restrictive lung disease/hypoventilation --> also associated with enthesitis, aka inflammation at site of tendon insertion into bone --> presents in YOUNGER MALES with low back pain, anterior uveitis, aortic regurgitation, limited chest expansion --> CXR shows narrowing/fusion of vertebral spine aka "bamboo spine" --> pelvic XR shows narrowing/fusion of sacroiliac joint --> note: need to monitor chest expansion to assess disease severity)

Young adult male with low back pain/stiffness worse in morning, redness of eyes, bounding pulses with wide pulse pressure, elevated PaCO2

Gonorrhea (caused by Neisseria gonorrhea: intracellular, aerobic, UNENCAPSULATED gram-negative diplococci that does produce maltose acid --> transmitted sexually or perinatally --> produces strong endotoxin, IgA proteases that allow infection of mucosa, and pilus that allows attachment to cell surface --> causes gonorrhea, septic arthritis, pelvic inflammatory disease, and Fitz-Hugh-Curtis syndrome --> diagnosis: gram stain or NAT --> prevent with condoms, no vaccine due to antigenic variation of pilus proteins --> treat with ceftriaxone, usually doctors add azithromycin for possible chlamydia co-infection)

Young adult male with painful burning sensation on urination, creamy purulent penile discharge, urinalysis shows WBCs but no organisms

Spontaneous pneumothorax (non-traumatic lung black-out found in patients without pre-existing pulmonary disease, usually TALL THIN MALES around age 20 --> occurs due to superficial alveoli in APEX experiencing greater pressure changes due to weight of lungs pulling down on apical tissue --> causes formation of subpleural blebs in apices --> blebs can spontaneously rupture thru visceral pleura, even while patient is at rest --> causes trapping of air between parietal and visceral spaces)

Young adult male with sudden onset of sharp left-sided chest pain and dyspnea, loss of negative intrapleural pressure

Chancre (primary syphilis caused by Treponema pallidum, a spirochete transmitted via sexual intercourse that causes localized genital disease --> diagnosis: dark-field microscopy to visualize treponemes in fluid from chancre + VDRL + RPR --> treat with penicillin G)

Young adult patient with SINGLE PAINLESS ulcer with heaped-up borders and clean base

Stapedius nerve injury (stapedius nerve: branch of facial nerve/CN7 that innervates stapedius muscle in middle ear cavity, which stabilizes stapes --> nerve can be injured directly or damaged via CN7 lesion --> causes stapes to oscillate more widely, producing hyperacusis/heightened sensitivity to everyday sounds --> patients often withdraw socially --> treatment: sound therapy using white noise)

Young adult patient with difficulty hearing in one year, unable to tolerate everyday sounds, ear pain

Fibroadenoma (most common tumor in pre-menopausal females --> estrogen-sensitive so size/tenderness increases with estrogen, aka before menstruation or during pregnancy --> grossly appears as small, well-defined, marble-like, mobile mass surrounded by fibrous capsule --> biopsy shows well-demarcated encapsulated proliferation of breast stroma and ducts, with stromal proliferation compressing ducts to slits --> BENIGN tumor with NO increased risk of cancer)

Young adult woman with palpable, smooth, firm, round, mobile, non-tender, and well-delineated lump in right breast, no breast pain, no changes in skin around lesion

Submucosal uterine leiomyoma (uterine fibroids: benign smooth muscle tumor that is estrogen sensitive --> SUBMUCOSAL uterine fibroids located below endometrium --> do not often cause irregular uterine enlargement, but are associated with prolonged/heavy menstrual bleeding and can cause miscarriages)

Young adult woman with pelvic pressure, heavy menstrual bleeding, recurrent pregnancy losses

Disseminated gonococcal infection (due to Neisseria gonorrhea, aka intracellular, UNENCAPSULATED, gram-negative diplococci that metabolizes glucose but cannot produce maltose acid --> contains strong LPS endotoxin and produces IgA protease --> transmitted via infected genital secretions during sexual contact --> initial GU infection can by asymptomatic or cause purulent cervicitis/urethritis --> disseminated infection presents with either purulent arthritis of knee or TRIAD of polyarthralgia, tenosynovitis, and dermatitis --> complications: osteomyelitis, Bartholin cyst/abscess, orchitis, prostatitis, PID, and Fitz-Hugh-Curtis syndrome aka perihepatitis with inflammation of liver capsule and "violin string" adhesions of peritoneum to liver --> diagnosis: Thayer-Martin agar, aka chocolate agar with vancomycin + TMP + colistin + nystatin, and NAT --> treat with ceftriaxone, usually add azithromycin for possible chlamydia co-infection --> prevent with condoms, as there is LACK OF VACCINE due to antigenic variation of pilus proteins)

Young adult patient with fever, malaise, migratory polyarthritis, tenderness along tendons, and small non-tender pustules on extremities

G6PD deficiency (glucose-6-phosphate dehydrogenase deficiency: X-linked recessive disorder in which lack of G6PD prevents conversion of G-6-P to 6-phosphogluconate, aka rate-limiting step in HMP shunt --> inhibition of HMP shunt/PPP causes decreased levels of NADPH, which is used to replenish glutathione to protect against oxidative stress --> PPP is the only mechanism for RBCs to generate NADPH, so G6PD deficiency causes RBCs to be highly susceptible to oxidative stress such as anti-malarial drugs, sulfonamides, dapsone, fava beans, infections --> unopposed oxidative stress causes oxidation of Hb and formation of "Heinz bodies," aka denatured globin chains precipitating within RBCs --> Heinz bodies removed by splenic macrophages, leaving behind "bite cells" --> leads to mainly intravascular hemolysis that presents with episodes of back pain, normocytic anemia, hemoglobinuria, jaundice with elevated UCB --> diagnosis: Heinz prep of peripheral smear + enzymatic study weeks after hemolytic episode resolves --> lab findings: ↓haptoglobin, ↑LDH, ↑reticulocytes, ↑UCB, peripheral smear shows bite cells)

Young adult patient with history of recent skin infection presents with weakness, malaise, dark urine, scleral icterus, and normocytic anemia with elevated reticulocyte count

Chancroid (caused by Haemophilus ducreyi: sexually transmitted infection that causes multiple EXTREMELY PAINFUL genital ulcers with associated inguinal adenopathy --> diagnosis: gram stain shows gram-negative rods in "school of fish" chain)

Young adult patient with multiple deep, purulent, painful ulcers with "ragged borders" and suppurative lymphadenitis

Granuloma inguinale (Donovanosis: caused by Klebsiella granulomatis, a gram-negative rod transmitted sexually --> causes PAINLESS beefy red genital ulcer that bleeds readily on contact --> diagnosis: genital lesion biopsy shows cytoplasmic Donovan bodies with bipolar staining)

Young adult patient with progressive, red, PAINLESS, serpiginous genital ulcer that bleeds on contact with no associated lymphadenopathy

Lymphogranuloma venereum (caused by Chlamydia trachomatis types L1-L3: obligate intracellular bacteria with atypical cell wall lacking peptidoglycans --> enters cells as elementary bodies via endocytosis, then transforms into reticulate bodies for replication by cell fission --> eventually released from host cell as elementary bodies and causes PAINLESS genital ulcer associated with PAINFUL lymphadenopathy/buboes --> diagnosis: PCR or NAAT or Giemsa stain showing cytoplasmic inclusions, aka reticulate bodies --> treat with doxycycline)

Young adult patient with small painless genital ulcer and swollen PAINFUL inguinal lymph nodes with ulcerations

Dysbetalipoproteinemia (type 3 familial dyslipidemia: defect in ApoE prevents chylomicron and VLDL remnants to be taken up by liver --> chylomicrons and VLDLs accumulate in circulating, leading to elevated cholesterol and TG levels --> presents with premature atherosclerosis and tuberoeruptive xanthomas on palms of hand)

Young adult patient with yellow skin nodules over palmar creases and small clusters of yellow papules on elbows/knees/buttocks, family history of MI at young age

Inflammatory bowel syndrome (IBS: recurrent abdominal pain associated with defecation, change in stool frequency, and/or change in form/consistency of stool --> NO structural abnormalities and can be diarrhea-predominant, constipation-predominant, or mixed --> presents in MIDDLE-AGED WOMEN with episodic abdominal pain with loose watery stools OR constipation that is relieved by defecation --> multifaceted pathophysiology --> treat with lifestyle modifications, dietary changes, and loperamide)

Young adult with episodic diffuse cramping lower abdominal pain associated with loose, watery stools that is relieved with defecation

Aortic dissection (longitudinal TEARING OF INTIMA that forms a false lumen within aorta that fills with blood --> associated with HTN, bicuspid aortic valve, CT disorders --> presents with sudden severe "tearing" chest pain that radiates to back, large BP disparity between the two arms --> if Stanford type A/proximal dissection involving ASCENDING aorta, can extend to aortic arch/descending aorta and result in acute aortic regurgitation or cardiac tamponade --> Stanford type B/distal dissection only involves descending aorta below left subclavian artery complications: organ ischemia, aortic rupture, death --> treat Stanford type A with surgery, treat Stanford type B with beta-blockers then vasodilators)

Young adult with history of cocaine abuse presents with fever, tachycardia, hypertension, dyspnea, diminished pulses in left arm, diffuse crackles in all lung fields, diastolic murmur heard at left sternal border, CXR shows widened aortic arch

Ovarian torsion (rotation of ovary around the suspensory ligament of ovary, aka infundibulopelvic/IP ligament: caused by presence of large ovarian mass such as cyst/neoplasm, which increases ovarian weight and causes it to twist around IP ligament --> occlusion of ovarian vessels and nerves, which run within IP ligament --> results in complete blockage of blood flow to ovary and venous drainage/lymphatics from ovary, resulting in edematous and ischemic torsed ovary --> presents with acute onset of unilateral pelvic pain, fever, nausea, vomiting --> gross ovary appears necrotic and hemorrhagic --> diagnosis: pelvic ultrasound that shows decreased or absent blood flow to ovary)

Young adult woman with acute onset of fever, nausea, right-sided pelvic pain that is worse with movement, pelvic US shows right adnexal mass with no blood flow to ovary

Fibrocystic change of breast (benign breast disease that presents with pre-menstrual breast pain or lumps, and often appears bilateral and MULTIFOCAL --> grossly appear as "blue-domed" cysts --> NON-PROLIFERATIVE changes include simple fluid-filled cysts, papillary apocrine metaplasia with fibrosis/cysts/enlarged epithelial cells with abundant pink cytoplasm, stromal fibrosis and NO increased risk of cancer --> PROLIFERATIVE changes: sclerosing adenosis with increased # of acini/stromal fibrosis/calcifications and 2X increased risk of cancer --> ductal or lobular hyperplasia with increased # of cells/fibrosis/cysts and 2X increased risk of cancer --> atypical hyperplasia with ATYPICAL cells/fibrosis/cysts and 5X increased risk of cancer)

Young adult woman with pre-menstrual breast pain and lumpy breast

Hartnup disease (autosomal recessive metabolic disorder caused by inactivating mutations in neutral AA transporter --> impaired transport of neutral AAs in small intestine and PCT, particularly tryptophan --> unable to produce niacin/vitamin B3, serotonin, and melatonin --> presents with pellagra-like dermatitis, diarrhea, cerebellar ataxia --> diagnosis: neutral aminoaciduria --> treatment: high-protein diet + daily niacin or nicotinamide)

Young boy with irritability, diarrhea, scaly erythematous skin lesions in sun-exposed areas, cerebellar ataxia, elevated neutral amino acids in urine

Pinealoma (CHILDHOOD brain tumor arising from pineal gland, and is quite similar to germ cell tumors --> produces hCG, so can cause precocious puberty in males --> can also result in compression of tectum causing vertical gaze palsy, and compression of cerebral aqueduct causing non-communicating hydrocephalus --> since pineal gland usually responsible for synthesizing melatonin, destruction of pineal gland can result in insomnia)

Young boy with vertical gaze palsy, headaches, papilledema, insomnia, and precocious puberty

Poliomyelitis (caused by poliovirus: part of picornavirus family, aka naked linear positive-sense ssRNA virus with icosahedral capsid --> transmitted fecal-orally, affects UNVACCINATED children --> replicates in Peyer's patches within oropharynx and small intestine, then travels via bloodstream to ventral horn of spinal cord --> causes destruction/death of LMNs --> presents in UNVACCINATED CHILDREN with malaise, headache, fever, nausea, asymmetric weakness, hypotonia, flaccid paralysis, fasciculations, hyporeflexia, muscle atrophy --> also associated with atrophy of respiratory muscles resulting in respiratory failure, and can cause aseptic meningitis --> CSF findings: lymphocytic pleocytosis, slightly elevated protein, NORMAL glucose --> diagnosis: viruses recoved from stool or throat)

Young child from Africa presenting with headache, recurrent fever, back pain, weakness of unilateral lower extremity with decreased reflexes and fasciculations

Brain AVM (brain arteriovenous malformation: results in subarachnoid hemorrhage, aka bleeding between arachnoid and pia mater --> usually due to a congenital defect --> presents in CHILDREN with "worst headache of my life" and nuchal rigidity, focal neuro deficits are rare --> diagnosis: CSF shows blood and/or yellow xanthrochromia, indicating presence of bilirubin --> treat with NIMODIPINE to prevent cerebral vasospasm 3-10 days later --> complications: communicating or non-communicating hydrocephalus)

Young child presents with thunderclap headache, nuchal rigidity, CSF shows blood and yellow coloration

Febrile seizure (occurs due to bacterial/viral pyrogens such as LPS inducing macrophages to activate and release IL-1, IL-6, and TNF-alpha --> reach perivascular cells of hypothalamus, where they increase COX activity --> increased PGE2 release from cell membrane --> increased temperature set point, usually to <104°F --> should only treat with SUPPORTIVE care including acetaminophen and ibuprofen, but does not prevent future febrile seizures)

Young child with a recent cold had a seizure in which he was unresponsive and had shaking arms/legs --> now presents with fatigue but alertness, temp of 104°, NO nuchal rigidity or photophobia

Vitelline duct cyst (enterocyst: forms during 7th week when peripheral portions of vitelline duct obliterate properly, BUT central part remains and forms a cyst --> connects to ileum and abdominal wall by fibrous bands --> usually symptomatic and discovered incidentally)

Young child with abdominal cyst connected by a fibrous band to the ileum and umbilicus

I-cell disease (inclusion disease/mucolipidosis type II: inherited lysosomal storage disorder characterized by defect in N-acetylgluosamyl-1-phosphotransferase --> causes failure of Golgi bodies to phosphorylate mannose residues on glycoproteins --> decreased mannose-6-phosphate prevents proteins from being trafficked to lysosomes, thus secretion of proteins into ECF --> presents with coarse facial features, gingival hyperplasia, clouded corneas, restricted joint movements, claw hand deformities, kyphoscoliosis, increased risk of infections --> lab findings: high plasma levels of lysosomal enzymes --> often fatal in childhood)

Young child with failure to thrive, developmental delay, recurrent ear infections, coarse facial features, corneal clouding, hepatosplenomegaly, restricted joint mobility, claw hand deformities, kyphoscoliosis

Kawasaki disease (mucucutaneous lymph node syndrome: medium-vessel vasculitis often seen in ASIAN CHILDREN <4y/o --> characterized by conjunctivitis, desquamating polymorphous rash on palms and soles, cervical lymphadenopathy, strawberry tongue, perioral erythema/fissuring, and hand/foot changes such as edema and periungual desquamation --> often occurs in CORONARY ARTERY, resulting in either coronary artery aneurysm or thrombosis that can manifest as acute MI or other cardiac problems --> treat with ASPIRIN and IVIG)

Young child with history of lymphadenopathy and rash on palms and soles presents with acute MI

Congenital urethral obstruction (due to either posterior urethral valves or duplex collecting system --> results in obstruction in urinary system that greatly increases risks of UTIs --> diagnosis: ultrasound shows hydronephrosis and dilated/thick-wall bladder --> NOTE: posterior urethral valves can ONLY occur in males due to malformation of Wolffian duct causing presence of posterior urethral membrane)

Young child with recurrent UTIs, ultrasound shows marked dilation of left ureter/renal pelvis with minimal left-sided renal function

Heat stroke (occurs when heat production exceeds heat dissipation, usually due to high external temperatures/exertion that overwhelm ability to sweat and cause body temp to >105°C --> initially presents with dizziness, mental confusion, headaches, and weakness --> eventually ceases oxidative phosphorylation, which depletes ATP and causes permanent end-organ damage --> presents with CNS dysfunction/confusion, ARDS, rhabdomyolysis, and end-organ damage --> treat with rapid external cooling, rehydration, and electrolyte correction)

Young child with temp of 106°F presents with confusion, shortness of breath, oliguria, diffuse muscle cramps and myoglobinuria

Herpes genitalis (primary genital herpes, usually caused by HSV-2: enveloped, linear, dsDNA virus --> transmitted via sexual contact or perinatally --> presents with multiple PAINFUL genital ulcers with erythematous base, dysuria due to irritation from ulcers, tender lymphadenopathy, and systemic symptoms such as fever/headache --> diagnosis: PCR or Tzanck smear showing multinucleated giant cells)

Young woman with low-grade fever, mild headache, vaginal pain during sexual intercourse, dysuria, no vaginal discharge, bilateral tender inguinal lymphadenopathy, genitals show multiple painful shallow ulcers with an erythematous base