Diseases of the Small Intestine
Meckel's Diverticulum
*Most common congenital abnormality of the GI tract *Outpouching of all three layers of bowel wall (TRUE diverticulum) *Caused by an incomplete obliteration of the vitelline duct (ie, omphalomesenteric duct) *Usually asymptomatic but presenting symptoms include painless bleeding due to ulceration of adjacent tissue from ectopic gastric mucosa with parietal cells *Rule of 2's **May become inflamed (diverticulitis) causing RLQ pain (clinically impossible to distinguish from appendicitis)* *In rare cases may cause obstruction or may be used as a lead point for intussusception *Fecal material may be felt in the umbilical area *Dx: 99mTc nuclear scan to identify parietal cells in ectopic gastric mucosa.
Describe whether the following findings increase or decrease in patients with Lactose intolerance *Breath hydrogen *pH of stool *Stool osmotic gap
Breath hydrogen: increased pH of stool: reduced due to *reducing* substances Stool osmotic gap: increased
What is the characteristic appearance of intussusception on ultrasound?
Bull's eye/Target lesion or Donut sign
What causes celiac disease?
Celiac disease (also called celiac sprue) is an autoimmune-mediated (type 4 hypersensitivity) intolerance to gliadin, a gluten protein found in wheat, rye, and barley. In celiac disease, helper T cell mediated autoimmune destruction causes damage to villi surface, leading to malabsorption and steatorrhea. Malabsorption primarily affects the distal duodenum and/or proximal jejunum.
What are some atypical presenting symptoms for a child with celiac disease?
Children may present with failure to thrive, and proximal muscle wasting may be seen. In up to one quarter of children diagnosed, Rickets may be a presenting symptom.
"Red currant jelly" stool in CHILDREN is associated with what condition?
Children with intussusception classically present "red currant jelly" stools. Note that red currant jelly stools are also seen in *acute mesenteric ischemia, which most commonly presents in adults, rather than children.*
Dermatitis Herpetiformis and Celiac Disease
Dermatitis herpetiformis is an autoimmune blistering disorder caused by IgA antibodies against tissue transglutaminase. IgA antibodies cross-react with the reticular fibers that are attached to the basement membrane in the dermal papillae. This triggers an immunologic cascade resulting in neutrophil recruitment. this ruins the connection between the epidermis and dermis and forms a blister (looks like herpes so herpetiformis) flesh-colored to erythematous excoriated papules or plaques with herpetiform (i.e., small, clustered) vesicles symmetrically distributed over extensor surfaces, including the elbows, knees, buttocks, and shoulders. resolve with Gluten free diet
Gold Standard of Diagnosis for Meckel's Diverticulum
Diagnosis of Meckel diverticulum is made via 99mTc nuclear scan to identify ectopic gastric mucosa in the RLQ It may miss those patients without ectopic gastric tissue
What 3 diagnostic antibodies can be present in patients with celiac disease? If a patient is IgA deficient, how does this change diagnosis?
Diagnostic antibodies for celiac disease include: IgA anti-tissue transglutaminase IgA anti-endomysial antibody IgG anti-deamidated gliadin peptides If a patient is IgA deficient, check for IgG antibodies for ^^^
What Congenital Anomaly is Duodenal Atresia associated with?
Down's Syndrome
Which histopathologic finding would you expect to find in Whipple disease? A Intensely PAS positive material in the muscularis mucosa B Macrophages in the submucosa C Intensely PAS positive material in the intestinal epithelium D Intestinal macrophages with extensive cytoplasmic inclusions E PAS staining macrophages
E PAS staining macrophages PAS staining macrophages are a hallmark of Whipple disease.
Celiac Disease is not associated with an increased risk of malignancy T/F?
F Associated with an increased risk of malignancy, specifically *T-cell lymphoma*. (risk of small bowel adenocarcinoma is also increased)
Celiac Disease is associated with malabsorption of?
Fat soluble vitamins (ADEK) Folate Iron B12 Calcium
Immunofluorescence of a skin biopsy taken from a lesion of Dermatitis herpetiformis shows what characteristic finding?
Granular IgA deposits at the tips of dermal papillae
What portions of the small intestine are primarily affected in celiac disease?
Malabsorption primarily affects the distal duodenum and/or proximal jejunum (exposed to the highest concentrations of dietary gluten)
PAS is a staining method that detects the presence of what type of molecule? Why is this effective in diagnosing Whipple's Disease?
PAS detects carbohydrates such as glycogen and glycoproteins Glycoproteins are present in the cell wall of T. Whippelii
What is the most common presenting symptom in Meckel's Diverticulum?
Painless Bleeding (May cause iron deficiency anemia)
What are four symptoms associated with carcinoid syndrome?
Symptoms of carcinoid syndrome include: *Flushing of the skin* *Secretory (watery, voluminous) diarrhea* *Wheezing, caused by bronchoconstriction and/or bronchospasm* *Tricuspid insufficiency/regurg or pulmonic valve stenosis (TIPS)*
What type of hypersensitivity is seen in Celiac Disease?
Type 4 Hypersensitivity
Which HLA subtypes are associated with celiac sprue?
DQ2 and DQ8
Carcinoid Tumor (General)
*Of neuroendocrine origin and derive from primitive stem cells, which can give rise to multiple cell lineages * Majority arise from midgut (most common being small intestine and appendix) *Most carcinoid tumors occur in *adults& and are very rare in children. *Slow growing *Carcinoid tumors can produce an excess of hormone-like substances, such as serotonin, bradykinin, kallykrein, histamine, and prostaglandins. * * * *
A 4-year-old girl has the sudden onset of abdominal pain and vomiting. She has a mass in the right lower quadrant and hyperactive bowel sounds. A segment of resected bowel is shown in the photograph. Which of the following is the most likely diagnosis? (A) Appendicitis (B) Intussusception (C) Meckel diverticulum (D) Necrotizing enterocolitis (E) Strangulated hernia
(B) Intussusception
A previously healthy 2-year-old boy is brought to the emergency department because of bloody stools for 2 days. His vital signs are within normal limits. Abdominal examination shows no abnormalities. Laboratory studies show: Hemoglobin 11 g/dL Hematocrit 37% Leukocyte count 9500/mm3 Platelet count 250,000/mm3 Test of the stool for occult blood is positive. During an emergency laparotomy, a 3 × 2-cm protrusion is found on the antimesenteric border of the small intestine approximately 50 cm proximal to the ileocecal valve. Which of the following is the most likely cause of this patient's condition? (A) Carcinoid tumor (B) Ectopic adrenal gland (C) Meckel diverticulum (D) Retrocecal appendix (E) Umbilical hernia
(C) Meckel diverticulum
A 6-year-old boy has a large intra-abdominal mass in the midline just above the symphysis pubis. During an operation, a cystic mass is found attached to the umbilicus and the apex of the bladder. Which of the following is the most likely diagnosis? (A) Hydrocele (B) Meckel's cyst (C) Meckel's diverticulum (D) Omphalocele (E) Urachal cyst
(E) Urachal cyst
Describe the histological presentation of Carcinoid Tumors
*"dense core bodies" seen on EM bodies are secretory granules *bright yellow tumor *****
Double bubble sign
**** What other diseases can present with Double bubble sign??
Intestinal Malrotation
*A congenital abnormality in the normal rotation that occurs around the SMA; *Leads to improper positioning of the bowel **Increased risk of midgut volvulus; typically presents as bilious vomiting* *Presentation: Malrotation itself may be asymptomatic. Complications include Midgut volvulus or duodenal obstruction due to Ladd's bands (peritoneal fibrous bands that may kink/compress the duodenum) *Dx: Barium enema shows malpositioning of cecum or Ligament of Treitz
Whipple's Disease
*Caused by infection from Tropheryma whipplei (Gram positive actinomycete) *Most commonly occurs in older men *Primarily causes malabsorption but can affect any organ *Classic triad = Arthralgia, diarrhea, mesenteric lymphadenopathy *Characterized by "foamy" macrophages loaded with partially destroyed T. Whipplei organisms (PAS +, diastase resistant) *Duodenal biopsy: foamy, PAS-positive macrophages in the lamina propria
What is the treatment of Dermatitis herpetiformis ?
*Dapsone* is an effective treatment for most patients. DH responds to dapsone so quickly (itching is significantly reduced within 2-3 days that this response may almost be considered diagnostic. However, dapsone treatment has no effect on any intestinal damage that might be present.
Pathophysiology of Celiac Disease
*Gliadin, a gluten protein, becomes an antigen by acting as a substrate for tissue transglutaminase *Tissue transglutaminase deaminates dietary gluten *Fragments are phagocytosed by antigen presenting cells (APCs) and presented to T-helper cells (via MHC 2) *Type 4 Hypersensitivity *Cytokines released promote aggregation of killer lymphocytes *CD8 T cells cause mucosal damage with loss of villi and proliferation of crypt cells *Primarily affects the distal duodenum and/or proximal jejunum (highest gluten exposure occurs)
What is the most common presentation of volvulus in an infant?
*In infancy, the most common presentation of volvulus is abdominal distention with acute onset of bilious vomiting. * Other signs and symptoms include: Abdominal pain Constipation Hematochezia (10-15% of patients, suggests the presence of bowel ischemia)
A mother brings her 2-year-old son to the pediatrician following an episode of abdominal pain and bloody stool. The child has otherwise been healthy and growing normally. On physical exam, the patient is irritable with guarding of the right lower quadrant of the abdomen. Based on clinical suspicion, pertechnetate scintigraphy demonstrates increased uptake in the right lower abdomen. Which of the following embryologic structures is associated with this patient's condition? 1. Metanephric mesenchyme 2. Ductus arteriosus 3. Vitelline duct 4. Paramesonephric duct 5. Allantois
3. Vitelline duct
How can Celiac Disease present with bleeding Diathesis?
Bleeding diathesis (increased tendency to bleed, secondary to malabsorption of fat-soluble vitamin K)
Borborygmi
Rumbling sounds caused by gas moving through the intestines, commonly referred to as stomach "growling").
Lactose Intolerance
*Inability to digest lactose into its constituents, galactose and glucose due to low levels of lactase enzyme in the brush border of the duodenum *Can be primary, secondary, or congenital *Presentation: vomiting, bloating, explosive and watery diarrhea, cramps, and dehydration *Typically not associated with weight loss (lactose is only one of the several sugars to absorb; fat absorption is unimpaired; no deficiency in calories) *Osmotic diarrhea due to bacterial fermentation of undigested lactose into small organic acids (osmotically active) *Dx: Positive hydrogen breath test *Tx: Dietary restriction of milk and milk products (except unpasteurized yogurt); Lactase pills
What are some extraintestinal manifestations of celiac disease?
*Iron deficiency anemia *Decreased bone mineral density *Neuropathy (motor weakness/parasthesia) *Dermatitis herpetiformis *Angular cheilitis and recurrent aphthous ulcers *Hormonal disorders (amenorrhea/infertility in women, impotence/infertility in men)
Describe the histopathological features of Celiac disease
*Mucosal inflammation *Crypt hyperplasia (appear deeper) *Villous atrophy (blunted/flat) *Increased number of intraepithelial CD8 T cells (intraepithelial lymphocytosis) *Increased cellularity of the lamina propria (proliferation of plasma cells, mast cells, eosinophils)
Intussusception
*Telescoping of proximal segment of bowel into distal segment (drag in by peristalsis) *May progress to infarction and obstruction *Commonly occurs at the ileocecal junction **Majority of cases occur in children* *Presentation: Sudden onset of intermittent, severe, crampy, progressive abdominal pain, sometimes with vomiting and "currant jelly" stools (containing blood and mucus). A vertically oriented mass may be palpable in the right upper quadrant.. Infants often draw their knees toward their chest *Dx: Bull's eye appearance on ultrasound/CT; *May reverse spontaneously *Tx: Idiopathic cases, contrast enema can be used both diagnostically and therapeutically. Surgical intervention is needed when a mass/tumor is present in adults
Lactose Absorption/ToleranceTest
*This test is rarely done in clinical practice. *Measure serial blood glucose levels after an oral lactose load. *A fasting serum glucose level is obtained, after which 50 g of lactose is administered. Measure the serum glucose level at 0, 60, and 120 minutes. *The diagnosis is confirmed if the serum glucose level fails to increase by 20 g/dL above the baseline*
Volvulus
*Twisting of the intestine around its mesenteric root (Surgical emergency) *Presents with features of both obstruction and infarction (arterial supply is compromised) **Increased risk in patients with malrotation of gut, pregnancy, chronic constipation* *Most commonly occurs in sigmoid colon (volvulus => obstruction and infarction)
Hydrogen Breath Test
*You will be asked to breathe into a balloon-type container. *You will then drink a flavored liquid containing lactose. *Samples of your breath are taken at set times and the hydrogen level is checked. *Normally, very little hydrogen is in your breath. But if your body has trouble breaking down and absorbing lactose, breath hydrogen levels increase. *The test is positive for lactase deficiency if administration of lactose produces symptoms and the level of hydrogen rises above 20 ppm*
Tropical Sprue
-A chronic malabsorptive disease with similar histological findings as celiac disease. -Occurs in countries where there is poor sanitation and hygeine -Arises after infectious diarrhea and RESPONDS TO ANTIBIOTICS -Damage is primarily in jejunum and ileum - Present with a megaloblastic (macrocytic) anemia from folic acid and b12 malabsorption
Celiac Disease
-AKA Gluten-sensitive enteropathy or Celiac sprue -Immune mediated damage of small bowel villi due to consumption of gluten containing foods (wheat, rye, barley) -associated with IgA deficiency -more common in Type 1 Diabetics (and other auto immune disorders) -more common in people of NE European descent (especially Ireland) -associated with HLA DQ2 and DQ8 -calcium absorption can be impaired => decreased bone density -associated with dermatitis herpetiformis -associated with T-cell lymphoma -damage is most prominent in distal duodenum/proximal jejunum -Tx:Gluten free diet; corticosteroids in nonresponsive cases; Dapsone for dermatitis herpetiformis
Clinical Features of Duodenal Atresia
1) Polyhydramnios 2) Distension of stomach and blind loop of duodenum (double bubble sign) no distal bowel gas (atresia); presence of distal gas may signify duodenal stenosis 3) Bilious vomiting (since the obstruction is distal to the point where bile enters the gut)
A 10-month old girl brought to the emergency department by her mother because of a 12-hour history of intermittent colicky pain and vomiting. She was diagnosed 1 week ago with otitis media and a 10- day course of amoxicillin therapy was initiated at that time. Now in the emergency department vital signs are temperature 37.7, pulse 168/min, respiration 32/min and blood pressure 82/46 mm Hg. Physical examination shows no abnormalities but is difficult because the infant fussy. Oral electrolyte solution is administered and the infant falls asleep. She is observed for 1 hour and discharged home. Twelve hours later, the patient is again brought to the emergency department because her symptoms have recurred. Vital signs now are temperature 37.4 C , pulse 170/min, respiration 42/min, and blood pressure 84/46 min Hg. Physical examination shows a well-developed, well-nourished infant who is fussy and crying. Tympanic membrane are dull but move with insufflation. Oral examinations shows swollen gums and erupting teeth. Examination of the skin sows one bruise over the right side of the forehead and one on her left leg. Chest is clear. Abdomen is soft with active bowel sounds, there is palpable fullness in the left upper quadrant. Rectal examination shows a formed stool with mucus that is positive for occult blood. Which of the following is the most likely explanation for the parent's condition. 1. Gastroenteritis 2. Intussusception 3. Pyloric stenosis. 4. Schonlein-Henoch purpura 5. Teething pain.
2. Intussusception
A 21-year-old female college student presents to the clinic complaining of intermittent diarrhea, abdominal pain, and bloating. She has had a feeling of general weakness and fatigue over the last month. She states that her stool has recently seemed to be "grease coated". She does not have any significant past medical history. Vital signs are T 98.9 F, HR 103, BP 110/75, RR 16, and SpO2 99%. Laboratory tests show an iron deficiency anemia. On physical exam, what skin condition is most likely associated with her presentation? 1. Red and white scaly patches or plaques on the top layer of the epidermis 2. Papulovesicular eruptions, usually distributed symmetrically on extensor surfaces 3. Pinkish-red, flaky, oval-shaped large patches on the torso in a characteristic "Christmas tree" distribution 4. Redness with yellow-grey-white flakes on the face, behind the ears, and in various skin folds 5. Tense bullae of the inner thighs, upper arms, trunk and extremities
2. Papulovesicular eruptions, usually distributed symmetrically on extensor surfaces Dermatitis herpetiformis is a chronic blistering, pruritic, papulovesicular skin condition commonly associated with celiac disease.
Which one of the following diagnostic tests provides the greatest sensitivity and specificity for diagnosing Whipple's disease? A. Electron microscopy to show intracytoplasmic vacuoles. B. Immunohistochemical staining to show antibodies against T. whipplei. C. Periodic acid Schiff (PAS) staining to show nucleolar inclusions. D. Sudan-black staining to show intranuclear lipoid bodies.
3. B: The correct answer is B. Choices A, C, and D are incorrect. Immunohistochemical staining for antibodies against T. whipplei has been used to detect the organism in various tissues. Electron microscopy may detect the distinctive trilaminar cell wall of T. whipplei. The classic tool for diagnosing Whipple's disease is PAS staining of small-bowel biopsy specimens, which on light-microscopical examination shows magenta-stained inclusions within macrophages of the lamina propria. Although not yet widely available, immunohistochemical staining provides greater sensitivity and specificity than does PAS staining. Sudan black is not used in the diagnosis of Whipple's disease.
A 17-year-old male presents to his primary doctor complaining about an extremely itchy rash on his elbows and other extensor surfaces. This rash is shown in Figure A. Given the clinical associations of this rash, what other disease must be considered in this patient? 1. Crohn disease 2. Ulcerative colitis 3. Celiac disease 4. Juvenile rheumatoid arthritis 5. Systemic lupus erythematosis
3. Celiac disease
A 54-year-old male presents to his primary care physician with complaints of severe diarrhea, flushing of the face, and several incidents of trouble breathing over the past week. A CT scan (Figure A) is obtained and shows a primary tumor in the small bowel (blue arrow) as well as metastasis to the liver (yellow arrow). The patient is referred to a surgeon for further management. The surgeon schedules a date to attempt surgical removal of all tumor tissue. The surgeon also decides to start the patient on a medication to control symptoms prior to surgery. Which of the following medications is the best choice for the management of this patient's symptoms? 1. Propranolol 2. Phenoxybenzamine 3. Octreotide 4. Propylthiouracil 5. Sumatriptan
3. Octreotide This patient is suffering from carcinoid syndrome due to a primary carcinoid tumor metastasizing to the liver. *Octreotide is a somatostatin analogue used to control the symptoms of carcinoid syndrome or employed in the preoperative period before removal of the tumor.* The classic presentation of carcinoid syndrome is due to excess levels of serotonin (5-HT) and includes diarrhea, facial flushing, right-sided heart pathology (tricuspid insufficiency and pulmonary stenosis), and bronchospasm leading to wheezing and trouble breathing. Carcinoid tumors within the GI tract that have NOT metastasized to the liver will not cause symptoms of carcinoid syndrome, as the liver metabolizes the 5-HT that is fed into the portal circulation.
A 14-month-old boy has iron-deficiency anemia refractory to iron therapy. His stool is repeatedly positive for occult blood. The parents bring the child to the emergency room after they notice some blood in his stool. Which of the following is the diagnostic gold standard for this patient's most likely condition? 1. Abdominal CT with contrast 2. Tagged red blood cell study 3. Technetium-99m pertechnetate scan 4. Colonoscopy 5. Capsule endoscopy
3. Technetium-99m pertechnetate scan The patient in this vignette most likely has a Meckel's diverticulum, which can be diagnosed with a technetium-99m pertechnetate scan. Meckel's diverticulum is a congenital anomaly of the intestine. In the embryo, the omphalomesenteric duct (also known as the vitelline duct or yolk stalk) connects the midgut lumen to the yolk sac. It normally obliterates during the 7th week of embryonic development. However, if it persists, it results in a small bulge in the intestine present at birth known as Meckel's diverticulum. Meckel's diverticulum is a "true" diverticulum; it contains mucosa, submucosa, and the muscular layer. Meckel's diverticulum may be remembered with the "Rules of 2": It occurs in 2% of the population, in the first 2 years of life, and 2 feet from the ileocecal valve. Martin et al. review the presentation and diagnosis of Meckel's diverticulum. When symptomatic, Meckel's diverticulum is often difficult to diagnose based on clinical presentation alone. *Technetium-99m pertechnetate scanning allows for detection of ectopic gastric tissue, which is present in up to 55% of Meckel's diverticulum. The scan may be more useful in children, as it has a sensitivity and specificity of 85% and 95% respectively in the pediatric population versus only 65% and 9% respectively in adults.*
An 8-month-old boy is brought to the emergency room by his mother who notes that the child has not been passing stool regularly. Palpation and radiographic imaging of the umbilical region reveal the presence of fecal material in an abnormal out-pocketing of bowel. Which of the following is a common complication seen in this condition? 1. Enlarged rugal folds 2. Dysplasia 3. Ulceration 4. Megacolon 5. Paneth cell metaplasia
3. Ulceration The patient described above is suffering from Meckel diverticulum. The most common complication is ulceration which can lead to bleeding. Meckel diverticulum results when the vitelline duct persists after birth. Because all layers of bowel wall are present, and the duct is continuous with the rest of the bowel, this is a true diverticulum. *Ectopic gastric mucosa may be found within Meckel diverticula, and the ectopic gastric secretions produced there can lead to ulcerations and eventually bleeding.* Martin et al. note that greater than 50% of patients with Meckel diverticula have ectopic tissue within the diverticulum. More commonly, the ectopic tissue is gastric but it may also be pancreatic. In terms of the pancreatic secretions, the alkaline nature of the secretions may also cause ulcerations.
A 22-year-old woman presents to her primary care physician complaining of a red, itchy rash on her elbows and shoulders for 2 months. She has no history of medical problems, and review of systems is positive only for occasional loose stools. She is appropriately prescribed dapsone, which relieves the rash within hours. What is the diagnosis? Topic Review Topic 1. Candida intertrigo 2. Porphyria cutanea tarda 3. Systemic lupus erythematousus 4. Dermatitis herpetiformis 5. Leprosy
4. Dermatitis herpetiformis This patient's presentation is consistent with dermatitis herpetiformis, a dermatologic manifestation of celiac disease. Dermatitis herpetiformis is a pruritic rash of extensor surfaces that occurs due to IgA deposition in the dermis. *It is treated with dapsone, and response to dapsone confirms the diagnosis of the condition. Response typically occurs within hours.* GI symptoms in patients with dermatitis herpetiformis and celiac disease are often absent, but the lesions respond to a gluten-free diet.
A 30-year-old Caucasian female presents with weight loss, pallor, and periodic abdominal discomfort. Physical exam reveals pruritic, red lesions on the patient's shoulders, elbows, and knees. An endoscopic duodenal biopsy is taken and shown in Figure A. Which of the following diseases is associated with the patient's condition? 1. Zollinger-Ellison syndrome 2. Hirschsprung's disease 3. Peutz-Jehger's polyposis 4. Hashimoto's thyroiditis 5. Helicobacter pylori infection
4. Hashimoto's thyroiditis Celiac disease is a chronic, hereditary, autoimmune intestinal malabsorption disorder caused by intolerance to gluten. *It is associated with other autoimmune diseases such as Hashimoto's thyroiditis and diabetes mellitus type I* Celiac disease commonly occurs in women in their third decade. Patients present with diarrhea, weight loss, pallor, and abdominal discomfort. Celiac disease is frequently associated with dermatitis herpetiformis, a papulovesicular rash on extensor surfaces. Treatment focuses on removing gluten from the patient's diet. Some refractory cases are treated with steroids.
A 53-year-old female visits her physician with watery diarrhea and episodic flushing. The patient reports that she is often short of breath, and a pulmonary exam reveals bilateral wheezing. A CT scan shows a mass in the terminal ileum. 24-hour urine collection shows abnormally elevated 5-hydroxyindoleacetic acid (HIAA) levels. Ultrasound demonstrates a tricuspid valve with signs of fibrosis with a normal mitral valve. A metastatic disease to which organ is most commonly associated with the patient's syndrome 1. Lung 2. Kidney 3. Brain 4. Liver 5. Pancreas
4. Liver The patient's symptoms, imaging, and laboratory results suggest a carcinoid tumor of the terminal ileum with metastasis to the liver. Typical carcinoid syndrome symptoms such as diarrhea, cutaneous flushing, and wheezing will manifest only if the tumor metastasizes to the liver. These tumors secrete a number of vasoactive substances, including serotonin and bradykinin, which are metabolized by the liver if the tumor remains confined to the bowel. If the tumor metastasizes to the liver, these products are not degraded and the patient will manifest the typical carcinoid syndrome symptoms. Tricuspid fibrosis is common in these patients with metastasis to the liver as the serotonin can affect the right side of the heart, however is broken down by the intrinsic monoamine oxidase of the lung resulting in a normal mitral valve. Elevated urine HIAA, a metabolite of serotonin (5-HT), can be a useful diagnostic test for carcinoid tumors.
Which one of the following antimicrobial regimens is bactericidal against T. whipplei in vitro? A. Erythromycin and imipenem. B. Hydroxychloroquine and doxycycline. C. Metronidazole and gentamicin. D. Sulfamethoxazole and levofloxacin.
4.B : The correct answer is B. Choices A, C, and D are incorrect. Doxycycline (200 mg per day) and an alkalinizing agent, hydroxychloroquine (200 mg three times per day), has thus far been the only successful bactericidal regimen against T. whipplei in vitro
A 58-year-old female presents to her primary care physician with a 1-month history of facial and chest flushing, as well as intermittent diarrhea and occasional difficulty breathing. On physical exam, a new-onset systolic ejection murmur is auscultated and is loudest at the left second intercostal space. Subsequent echocardiography reveals leaflet thickening secondary to fibrous plaque deposition on both the pulmonic and tricuspid valves. Which of the following laboratory abnormalities would most likely in this patient? Topic Review Topic 1. Decreased serum chromogranin A 2. Elevated serum bicarbonate 3. Elevated urinary vanillylmandelic acid 4. Elevated serum potassium 5. Elevated urinary 5-hydroxyindoleacetic acid
5. Elevated urinary 5-hydroxyindoleacetic acid This patient's presentation is consistent with a diagnosis of carcinoid syndrome. Elevated 24 hour urine levels of 5-hydroxyindoleacetic acid (5-HIAA) are diagnostic of carcinoid syndrome. The GI tract is a common location for carcinoid tumors; however, carcinoid syndrome does not manifest until the tumor has metastasized to the liver or outside the GI tract, allowing for the released serotonin to escape hepatic degradation. Common presenting symptoms of carcinoid syndrome include flushing, diarrhea, tachycardia/hypotension, bronchospasm, telangiectasia, and right-sided heart failure. The right-sided heart disease of carcinoid syndrome involves endocardial plaques and fibrous intimal thickening, resulting in pulmonic stenosis, tricuspid insufficiency, and possibly restrictive cardiomyopathy.
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What are the rules of 2's regarding Meckel diverticulum?
A mnemonic that can be used is the six 2's : 2 inches long 2 feet from ileocecal valve 2% symptomatic First 2 years of life 2 times as likely in males 2 types of ectopic tissue
Refractory Celiac Disease is suggestive of additional complication?
A rare condition in which the symptoms of celiac disease (and the loss of intestinal villi) do not improve despite many months of a strict gluten-free diet. Corticosteroids may be helpful in these patients *Small bowel carcinoma and T- Cell lymphoma may be present*
A 3-year-old boy has a 5-week history of weight loss and bulky, frothy, foul-smelling stools. Dietary modification results in clinical improvement. Which of the following is the most likely finding on examination of a biopsy specimen from the small intestine? A) Atrophy of villi and microvilli B) Degenerative changes of the myenteric plexus C) Multiple outpouchings through the muscle coat D) Numerous ulcerations and pseudopolyps E) Pseudomembrane covering the luminal surface
A) Atrophy of villi and microvilli
Symptoms of Lactose Intolerance
Abdominal pain Bloating Flatulence Osmotic diarrhea Vomiting (particularly in adolescents) Borborygmi may be audible
What are Ladd Bands?
Abnormal fibrous peritoneal bands that can occur in patients with malrotation. These congenital bands extend from the right lateral abdominal wall, across the duodenum and attach to the undescended caecum Ladd's bands compress the duodenum and can potentially cause duodenal obstruction
What hormonal disorders are associated with Celiac Disease?
Amenorrhea, delayed menarche, and infertility in women and impotence and infertility in men
What does the D-xylose test assess?
An assessment of the absorptive capacity of the proximal small intestine. D-xylose absorption requires an intact mucosa only
Ectopic mucosa in meckel's diverticulum
Approximately 50% contain ectopic gastric mucosa; rarely, colonic, pancreatic or endometrial tissue is present. Gastric or pancreatic mucosa can cause peptic ulcers or pancreatic ulcers respectively
Abetalipoproteinemia
Autosomal recessive deficiency of apolopoprotain B-48 and B-100 Clinical Features: -malabsorption --> due to defective chylomicron formation (requires B-48) -absent plasma VLDL and LDL (require B-100)
A 47-year-old male is brought to the emergency department for severe vomiting. He reports passing no flatus for 12 hours despite an increasingly distended abdomen. Which of the following represents the greatest risk factor for small bowel obstruction? A History of colon cancer B History of colon resection C History of asymptomatic diverticulosis D History of fecal impaction E History of recent travel
B History of colon resection Small bowel obstruction (SBO) is most commonly caused by intra-abdominal adhesions, which can result following abdominal surgery (e.g. colon resection). While fecal impaction and colonic masses can cause obstruction, these are large bowel obstructions, not SBOs. History of recent travel may lead to traveler's diarrhea, which does not cause SBO. Asymptomatic diverticulosis is not associated with SBO.
A 32 yr female presents with diarrhea, wt loss for years now presents with diffuse bone pain. the diarrhea improves on diet free in wheat; barley; rye. what is most likely seen on her serum serology a) increase PTH; increase PO4 & Ca2+ b) increase PTH; decrease PO4 & DECREASE Ca 2+ c) increase PTH; decrease PO4 & INCREASE Ca 2+ d) decrease PTH; PO4 & Ca 2+
B) B), because celiac disease-> malabsorption-> decreased vit D absorption -> decreased Ca2+ and PO4, which increases PTH
A 45-year-old woman comes to the office because she has had sores in her mouth intermittently during the past 4 to 5 weeks. Futher questioning discloses that the patient has a longstanding history of intermittent diarrhea, abdominal pain, and bloating, for which she has not sought care in the past. She also has had difficulty maintaining he weight despite following a regular diet. She takes no medications. She appears thin. BMI is 18 kg/m2. Vital signs are tmeperature 37.0 C, pulse 72/min, respirations 12/min, and blood pressure 118/78 mm Hg. Physical examination discloses three small ulcerations of the oral mucosa. The remainder of the physical examination discloses no abnormalities. Hematocrit is 30.5% and hemoglobin concentration is 9.7 g/dL. Peripheral blood smear shows microcytic erythrocytes. Which of the following is the most likely underlying cause of this patient's condition? A) A gastrin-secreting tumor of the pancreas B) An immune response to gliadin proteins C) Infection with Helicobacter pylori D) Infection with herpes simplex E) Infiltration of eosinophils into the intestinal mucosa
B) An immune response to gliadin proteins Diarrhea + abdominal pain/bloading + microcytic anemia (iron deficiency anemia) + apthous ulcers= Celiac
A 35-year-old man has a 6-year history of weight loss, chronic abdominal pain, bloating, and frequent voluminous, greasy, malodorous stools. He had similar symptoms as an adolescent, but they resolved spontaneously within 2 years. His mother has a similar illness that is controlled by restricting wheat, barley, and rye in her diet. In addition to the gastrointestinal symptoms, the patient has a chronic pruritic rash shown in the photograph of his elbow. Which of the following is the most likely diagnosis of this patient's skin condition? A) Bullous pemphigoid B) Dermatitis herpetiformis C) Epidermolysis bullosa D) Erythema nodosum E) Pemphigus vulgaris
B) Dermatitis herpetiformis
A 14-month-old girl is brought to the physician because of a 14-hour history of irritability and episodes of drawing her knees toward her chest. During this period, she has vomited nonbilious fluid twice and had bowel movement containing a small amount of blood. She has an upper respiratory tract infection 2 weeks ago. She is listless except for intermittent episode of discomfort. Her temperature is 38°C (100.4°F). Abdominal examination shows right-sided tenderness without guarding or rebound; bowel sounds are present. Rectal examination shows bright red blood and mucus. An X-ray of the abdomen shows no abnormalities. Which of the following is the most appropriate next step in management? A) X-ray of the upper gastrointestinal tract with contrast B) Water soluble contrast enema C) Corticosteroid enemas D) Admission to the hospital for total parenteral nutrition E) Immediate laparotomy
B) Water soluble contrast enema
A 16-month-old boy is brought to the emergency department because of 2- to 3-minute episodes of acute abdominal pain over the past 6 hours. During the episodes, he turns pale, screams, and draws up his knees. He has also passed one bloody stool. A mass is palpated in the right upper quadrant of the abdomen. Which of the following is the most appropriate next step in management? A) Nothing by mouth, administration of fluids and antibiotics, intravenously B) Water-soluble contrast enema C) CT scan of the abdomen D) Colonoscopy E) Laparotomy
B) Water-soluble contrast enema
A 44-year-old male is visits your office for evaluation of a papulovesicular skin rash. The patient also complains of periodic abdominal discomfort, weakness and diarrhea. You send the patient for a duodenal biopsy and it shows 'flat' intestinal epithelium. This patient most likely suffers from which of the following? A. Chronic pancreatitis B. Celiac disease C. Whipple disease D. Abetalipoproteinemia E. Crohn's disease
B. Celiac disease The patient most likely suffers from Dermatitis herpetiformis, which is characterized by groups of small vesicles that occur on extensor surfaces. Knees, elbows, buttocks, and back are the most typical locations for the rash. The eruptions are symmetrically distributed and extremely pruritic. Dermatitis herpetiformis is an autoimmune disorder associated with celiac disease (gluten-sensitive enteropathy). Skin biopsy will show neutrophils and fibrin at the tips of dermal papilla, forming, and microabscesses. Immunofluorescence reveals IgA deposits also present in the tips of dermal papillae
A previously healthy 10 month old boy is brought to emergency department by his parents because he has vomited twice during the past 2 hours. During this period he has had episodes of inconsolable crying and has passed one bloody stool. On arrival he appears lethargic and is difficult to arouse. His temperature is 38C (100.4F), pulse is 110/min, respiration are 24/min, and blood pressure is 90/65 mm Hg. The abdomen is soft with no masses or organomegaly. Rectal exam shows bloody mucus in the rectal vault. Which of the following is the most appropriate next step in diagnosis? A. Test of the stool for Clostridium difficile toxin B. Contrast enema C. Upper gastrointestinal series with small bowel follow-through D. CT scan of the head E. Colonoscopy
B. Contrast enema
Which one of the following is a characteristic dermatologic manifestation of Whipple's disease? A. Dermal fibromas. B. Melanoderma. C. Scleroderma. D. Vitiligo.
B. Melanoderma The correct answer is B. Choices A, C, and D are incorrect. Cutaneous manifestations of Whipple's disease vary. Melanoderma is a classic finding, but it is rarely observed these days, since Whipple's disease is recognized earlier in its course-
Which one of the following is implicated in the pathogenesis of Whipple's disease? A. Autoantibodies generated in response to Tropheryma whipplei. B. The failure to degrade bacterial antigens within macrophages effectively. C. The inability of macrophages to phagocytose T. whipplei efficiently. D. Excessive production of interleukin-12 in response to T. whipplei.
B. The failure to degrade bacterial antigens within macrophages effectively. The correct answer is B. Choices A, C, and D are incorrect. Several studies have shown defective macrophage function in patients with Whipple's disease. Although macrophages from affected patients phagocytose bacteria normally, they appear to be unable to degrade bacterial antigens efficiently. Experimental data suggest that this inability to degrade bacterial antigens is related to inadequate production of interleukin-12, which may lead to diminished interferon- production by T cells and defective macrophage activation. Humoral responses do not appear to be implicated in Whipple's disease.
A 62-year-old woman comes to the physician because of bloating and cramping abdominal pain and intermittent diarrhea over the past 5 years. Her symptoms have increased over the past month since she started a new diet that emphasizes yogurt and cottage cheese as low-fat sources of calcium and protein. Vital signs are within normal limits. Abdominal examination shows diffuse tenderness to palpation with no rebound tenderness; there are no masses or organomegaly. Bowel sounds are increased. Test of the stool for occult blood is negative. Which of the following is the best explanation for this patient's diarrhea? A) Impaired intestinal motility B) Inflammatory process C) Malabsorption D) Secretory process
C) Malabsorption
A 48-year-old Caucasian man comes to the physician with 3 months of chronic diarhea and abdominal pain. He has lost approximately 9 kg (20 obs) during that time. He also ha a 4-year history of migratory arthitis of the knees, hips, and elbows. A colonoscopy shows no significant findings. An endoscopic biopsy of the duodenum shows moderate villous atrohpy and numerous macrophages in the lamina propria containing gram-positive bacilli, as shown. Which of the following stains was most likely used? A) Congo red B) Crystal violet C) Periodic acid-Schiff D) Silver stain E) Ziehl-Neelsen stain
C) Periodic acid-Schiff
A 20-year-old man has gastrointestinal bleeding due to Meckel's diverticulum. Histologic evaluation of the resected diverticulum is most likely to show A) acute bacterial inflammation B) carcinoid tumor C) gastric mucosa D) an impacted enterolith E) varices at the neck of the diverticulum
C) gastric mucosa Approximately half of Meckel's diverticulum cause ulceration, inflammation, and GI bleeding because of the presence of ectopic acid-secreting gastric epithelium. Note: pancreatic tissue may sometimes occur in these diverticula as well.
A 7 day old girl is brought to the emergency department because she has vomited green liquid during feeding attempts for the past 12 hrs. She has cried incessantly during this period. She did not have pripr feeding problems or any other symptoms. She was born at term following an uncomplicated pregnancy, labor & delivery. She was discharged from the hospital at the age of 2 days. On arrival, she is grunting. Her temp. is 101.8 F, pulse 165/min, resp. 50/min & BP 88/50 mm Hg. The abdomen is distended, firm & diffusely tender. Which of the following is the most likely explanation for this patient's symptoms? A) distention of the hepatic capsule B) inflammation of the gallbladder C) obstruction of the small bowel D) rupture of renal cysts E) torsion of the ovaries
C) obstruction of the small bowel Midgut volvulus = malrotated bowel resulting in proximal bowel obstruction & ischemia. Typically the neonate is entirely normal for a period before suddenly presenting with bilious vomiting. Note Duodenal atresia would also have obstruction as well but would cause much earlier bilious vomiting (1st day of life). Duodenal atresia due to failure of bowel to recanalize. Double bubble sign.
A 45-year old Asian-American female presents to the family physician office for bloating, flatulence, abdominal cramps and explosive watery diarrhea following ingestion of dairy products. She denies any weight loss. She also denies bone pain or easy bruising. Physical examination reveals abdominal distension and borborygmi. You decide to investigate the patient further. Which of the following test result is most likely to be observed? A. Positive Clinitest of stool for oxidizing substances B. Decreased stool osmotic gap C. Positive hydrogen breath test D. Alkaline stool pH E. Positive acid steatocrit test
C. Positive Hydrogen Breath Test Lactose intolerance, a disorder in which, lactose in milk and dairy products is not absorbed; it is most commonly seen in Asian-Americans (90%). Lactase is a brush border enzyme that hydrolyses lactose, and *its concentration declines steadily into adulthood especially in people of non-European ancestry.* Lactose intolerance manifests as osmotic diarrhea after ingestion of dairy products, accompanied by abdominal cramps, bloating and flatulence. Lactose breath hydrogen test has largely replaced the lactose tolerance test (based on measurement of blood glucose after oral lactose administration), which is cumbersome and time consuming (Choice C). A rise in breath hydrogen after ingestion of lactose is a positive test indicating bacterial carbohydrate metabolism. (Choice A): Lactase deficiency is characterized by a positive Clinitest of stool for reducing substances (undigested lactose). (Choice B): The diarrhea secondary to lactase deficiency has a high osmotic gap, due to the unmetabolized lactose and organic acids. The osmotic gap is calculated as 290 - [2 (stool Na + stool K)] and is greater than 50 mOsm/kg in all forms of osmotic diarrhea. (Choice D): The stool pH is acid in lactase deficiency due to the fermentation products. (Choice E): Acid steatocrit is a test for fat malabsorption, not carbohydrate malabsorption. Educational objective: Lactose intolerance is characterized by a positive hydrogen breath test, positive Clinitest of stool for reducing substances and increased stool osmotic gap.
A 6-year-old girl is brought to the pediatrician for the first time by her mother. Her mother states that her family just emigrated from China and her daughter has seemed to have difficulty adjusting to the American diet. Specifically, she seems to have abdominal discomfort and increased flatulence whenever she eats milk or cheese. The pediatrician orders a test to diagnose the patient. Which of the following results is most likely to be observed in this patient? A. Negative hydrogen breath test B. Abnormal small bowel biopsy C. Positive hydrogen breath test D. Positive technetium 99 scan E. Abnormal abdominal ultrasound
C. Positive hydrogen breath test This patient presents with lactose intolerance. On testing, she would have a positive hydrogen breath test. Lactose intolerance is the inability to digest lactose, a common disaccharide, due to a deficiency of the digestive enzyme lactase. It causes osmotic diarrhea whenever lactose is ingested and produces abdominal pain, flatulence, and diarrhea. It is commonly diagnosed by a positive hydrogen breath test. The hydrogen breath test is performed by administering a small amount of lactose and measuring hydrogen breath levels every 15, 30 or 60 minutes for three hours. If the level of hydrogen rises above 20 ppm, the patient is diagnosed with lactose intolerance. Treatment is avoidance of dairy products or lactase replacement prior to meals containing lactose.
When does Celiac Disease usually present?
Can present at any age, but characteristically celiac disease manifests *during infancy and before school age.* In the classic form of childhood celiac disease, symptoms and signs of malabsorption become obvious within some months of starting a gluten-containing diet.
Which side of the heart is affected by carcinoid heart disease? Why is the opposite side unaffected?
Carcinoid heart disease is characterized by pathognomonic plaque-like deposits of fibrous tissue in the valves of the right heart leading to tricuspid valve regurgitation and pulmonary valve stenosis. *Left heart lesions are not seen because the lungs (like the liver) contain MAO, which inactivates humoral substances before they are returned to the left heart.*
Aside from carcinoid tumors of the ileum and metastatic disease, what other tumors can lead to carcinoid syndrome?
Carcinoid syndrome can rarely be caused by lung carcinoid tumors, islet cell carcinoma, and medullary thyroid carcinoma.
Why is carcinoid syndrome strongly associated with metastatic disease?
Carcinoid syndrome is strongly associated with metastatic disease, because the responsible neoplastic growth must secrete vasoactive substances into non-portal venous circulation. Substances released by tumors confined to the intestine are metabolized to inactive forms by "first pass" metabolism of the liver.
What is the treatment of carcinoid syndrome?
Carcinoid syndrome is treated with octreotide, a somatostatin analogue that, among other things, inhibits the release of serotonin. Surgical resection and chemotherapy with 5-fluorouracil and doxorubicin are other treatment options.
Patients with carcinoid syndrome are at risk for what vitamin deficiency?
Carcinoid tumors use the amino acid tryptophan to produce the excess serotonin. Because tryptophan is normally used to make niacin (vitamin B3), people may rarely develop a niacin deficiency, which can cause the disease pellagra
Location of small intestine damage (Tropical Sprue vs Celiac Sprue)
Celiac Sprue: Distal duodenum and Proximal jejunum Tropical Sprue: Jejunum and Ileum
What congenital condition predisposes a patient to midgut volvulus?
Congenital Malrotation
A 19 year old African American man comes to physician because of 9 month history of 6-12 hour episodes of intermittent watery diarrhea associated with abodominal cramps and bloating. he occasionally has had diarrhea after meals since the age of 12 years, but it has been worse since he started college 1 year ago. examination shows no abnormalities. which of following is the most likely cause of this pateints diarrhea? A) Bacterial overgrowth in the colon B) Decreased bacterial growth in colon C) Decreased bowel motility D) Digestive enzyme deficiney E) Immunologic damage to microvilli of the bowel
D) Digestive enzyme deficiney
What is D-xylose?
D-xylose is a simple sugar which doesn't need to undergo any digestive process before it can be absorbed. Its absorption only requires an intact proximal small bowel mucosa. In normal individuals, 25 grams of D-xylose ingestion leads to a urinary excretion greater than 4.5 grams in 5 hours.
A 45-year old comes to your office for evaluation of diarrhea of 8 months duration. He says that he has lost almost 15 lbs during the past 8 months. He denies any blood in the stools. 24 hour stool collection reveals fecal fat of 10 gm/day. Stool microscopy reveals no pathogens and no leucocytes. D-xylose test was performed which shows that less than 2 grams of D-xylose is excreted in urine in 5 hours. D-xylose test was re-performed after treatment with antibiotics but excretion is still less than 2 grams in 5 hours. Based on these findings, what is the most likely diganosis? A. Lactose intolerance B. Bacterial overgrowth C. Pancreatic insufficiency D. Whipple's disease E. Terminal ileal disease
D. Whipple's disease In cases of bacterial overgrowth, the values of D-xylose absorption return to normal after treatment with antibiotics. Whipple's disease must be treated for a long time before D xylose test becomes normal. In terminal ileal disease, bile salts are decreased due to impaired enterohepatic circulation, and as a result absroption of fats will be impaired but D xlose test should be normal as the duodenum and jejunum are unaffected
Duodenal Atresia
Duodenal atresia is a condition where there is occlusion of the duodenal lumen secondary to failed recanalization. thought to occur during weeks 8-10 of development Associated with Down Syndrome
A 43-year-old male with a chief complaint of chronic fatigue is found to have a megaloblastic anemia due to vitamin B12 deficiency. Review of systems reveals he has chronic diarrhea and fatty stools. If the patient is originally from the Caribbean, which of the following treatments is likely to help? A Cyanocobalamin B Iron sulfate C Dietary restriction D Fluconazole E Tetracycline
E A patient from the tropics with diarrhea, malabsorption, and vitamin deficiency may have tropical sprue. The treatment is empiric antibiotics.
A 65-year-old woman with chronic constipation comes to the emergency department because of a 3-day history of abdominal pain. Abdominal examination shows distention with tenderness in the left lower quadrant. Sigmoidoscopy shows no tumors, but the scope cannot be inserted beyond 15 cm because of abrupt luminal narrowing. Which of the following is the most likely diagnosis? A) Appendicitis B) Diverticulosis C) Small-bowel obstruction D) Volvulus of the cecum E) Volvulus of the sigmoid colon
E) Volvulus of the sigmoid colon
Lactose Intolerance causes a secretory diarrhea T/F?
F! Lactose intolerance causes an osmotic diarrhea due to bacterial fermentation of undigested lactose into small organic acids which are osmotically active
Why is the pH of stool decreased in patients with Lactose intolerance?
Fermentation of undigested lactose by gut bacteria results in increased production of short chain fatty acids (acetate, butyrate, propionate) that acidify the stool
What mnemonic can we use to remember the symptoms of Whipple Disease?
Foamy Whipped cream in a CAN -FOAMY macrophages in intestinal lamina propria -WHIPPlei CAN -*Cardiac (endocarditis/ valve disorders)* -*Arthralgia* -*Neurologic symptoms* *Can also present wiht melanoderma/skin pigmentation *Mesenteric Lymphadenopathy *Nystagums
A child with a recent history of adenovirus infection presents with intussusception. What is the most likely lead point that caused the intussusception in this patient?
Hypertrophied Peyer Patches While the majority of cases of intussusception in children are idiopathic, viral infections, in particular adenovirus, can cause intussusception by inducing hypertrophy of Peyer patches in the distal ileum. These hypertrophied Peyer patches act as a lead point.
Lead point of intussusception
In adults, intussusception is usually accompanied by a lead point ("something to hook on") in children, usually no lead point is identified and it is idiopathic children: Increasing evidence that it is commonly due to enlarged lymphoid tissue secondary to a viral infection adults: tumor
What is the most common cause of intussusception in adults?
In adults, the most common cause is tumor within the intestinal tract.
D-xylose and Celiac Disease
In individuals with Celiac disease, the small intestinal mucosa is damaged, hence, imparing D-xylose absorption. *(also impaired in Tropical Sprue and Whipples)*
D-xylose and Bacterial Overgrowth
In individuals with bacterial overgrowth, there is increased bacterial consumption of D-xylose, causing decreased D-xylose absorption.
D-xylose and Pancreatic Insufficiency
In individuals with pancreatic insufficiency, there is deficiency of pancreatic enzymes which leads to impaired digestion of fats, and absorption of D-xylose is not affected in any way. Pancreatic Insufficiency = Normal D-Xylose Test
Most common site of volvulus in infants and children _________ Most common site of volvulus in young adults Most common site of volvulus in elderly _________
Infants and children: Midgut (small bowel) Young adults: Cecum Elderly: Sigmoid colon
A 9 month old, chubby, healthy looking little boy has episodes of colicky abdominal pain that make him double up and squat. The pain lasts for about one minute, and the kid looks perfectly happy and normal until he gets another colick. Physical exam shows a vague mass on the right side of the abdomen, an "empty" right lower quadrant and currant jelly stools.
Intussusception
In children younger than 3 years, what is the most common location of small bowel obstruction?
Intussusception at the ileocecal junction is the *most common cause of small bowel obstruction in children between 6 and 36 months.*
Embryological role of Vitelline Duct
Joins yolk sac to midgut lumen Early in embryonic life, fetal midgut receives nutrition from yolk sac via vitelline duct (AKA omphalomesenteric duct, yolk stalk) Forms Week 4 Regresses by week 7
Where is lactase usually located?
Lactase is normally located in the brush border of the enterocytes of the intestinal villi.
A child suffers from an osmotic diarrhea a week after a viral "stomach bug," what is a likely reason for this?
Lactose Intolerance
What is the classical location of the foamy macrophages seen in Whipple's Disease?
Lamina propria of the small bowel
Carcinoid Tumor (Small Intestine)
Malignant proliferation of neuroendocrine cells low-grade malignancy (small cell carcinoma of the lung = high-grade malignancy of neuroendocrine cell) -tumor cells contain neurosecretory granules that are positive for *chromogranin* (an immunohistochemistry stain) Can arise anywhere along the gut; *small bowel is most common site* -grows as submucosal polyp-like nodule Often secretes serotonin -serotonin is released into portal circulation and metabolized by liver monoamine oxidase (MAO) into 5-HIAA -5-HIAA is excreted in the urine -*Carcinoid syndrome may occur only if Carcinoid tumor metastastasizes to the liver* (dumps into the hepatic vein)
Most common pathologic lead point of intussusception in children?
Meckel's Diverticulum
Whipple's disease more often occurs in which age and gender?
Most often occurs in older men
Describe the appearance of villi in a patient with lactase deficiency?
Normal appearing villi Because the defect is biochemical, biopsy histology is generally unremarkable Except when 2° to injury at tips of villi (eg, viral enteritis)
Complications of volvulus include:
Obstruction Necrosis Perforation Recurrent volvulus
What classic sign is seen on radiographs in a patient with sigmoid volvulus?
On KUB (kidney, ureter, bladder) radiographs, a classic *"coffee bean sign"* may be seen, indicating a sigmoid volvulus.
Describe the Pathophysiology of fat malabsorption and steattorhea in whipple's disease?
Organism laden macrophages compress the lacteals in the intestinal lamina propria. This prevents chylomicrons from getting into the lymph and blood Thus, the malabsorptive diarrhea of Whipple disease is due to impaired lymphatic transport.
Primary vs Secondary vs Congenital Lactose Intolerance
Primary: age-dependent decline after childhood (absence of lactase-persistent allele), common in people of Asian, African, or Native American descent. Secondary: loss of brush border due to gastroenteritis (e.g., rotavirus), autoimmune disease, etc. (usually self limited lactose intolerance; resolves on its own) Congenital lactase deficiency: Rare AR disorder, due to defective gene. *Primary is the most common* Since lactase is located at the tips of intestinal villi, self-limited lactase deficiency can occur following a viral enteritis.
Carcinoid Heart Disease
Right sided valvular fibrosis Leads to tricuspid regurgitation and pulmonary valve stenosis *********
A patient with suspected celiac disease undergoes a biopsy, which confirms the diagnosis of celiac disease. What is the most likely reason that this patient has negative serology for 2 commonly used diagnostic antibodies: anti-tissue transglutaminase and anti-endomysial?
Since IgA deficiency is associated with celiac disease, patients with the disease may have falsely negative serology since two of the commonly used diagnostic antibodies are IgA (IgA anti-tissue transglutaminase, IgA anti-endomysial).
What are the most common causes of small bowel obstruction in adults?
Small bowel obstruction occurs when the normal flow of intraluminal contents is interrupted. Obstruction can either be functional or due to mechanical obstruction. The common causes of small bowel obstruction in the US are adhesions (most common) and hernias. In developing countries, hernias are more common than adhesions. US: Adhesions > hernias Developing World: Hernias > Adhesions
Dermatitis herpetiformis is usually distributed over which areas of the body?
Symmetrically over extensor surfaces shoulders, elbows, knees
The small intestine is rarely affected by neoplasia T/F?
T. Tumors of the small intestine make up a small percentage of gastrointestinal neoplasms
What is the most common site of GI carcinoid tumors?
The appendix is the most common site of gut carcinoid tumors, followed by the small intestine (primarily ileum) (score 95) Small intestine is most common site (Pathoma)
Which vaccine is contraindicated in children with a history of intussusception?
The oral *rotavirus vaccine* is contraindicated in children with a history of intussusception since intussusception is a rare adverse effect of this vaccine.
What proportion of carcinoid tumors: - Metastasize? - Present with 2nd malignancy? - Present as multiple tumors?
The rule of 1/3s for carcinoid syndrome states that: 1/3 metastasize 1/3 present with a 2nd malignancy 1/3 are multiple
Transmural vs Mucosal Infarction of the Small Bowel
Transmural: Due to embolism/thrombosis of SMA or mesenteric vein Mucosal: Due to Marked Hypotension
Which condition is associated with drainage of meconium from the umbilicus?
Vitelline Fistula Occurs when the vitelline duct persists, thereby forming a direct connection between the intestinal lumen and the outside of the body at the umbilicus *Meckel's diverticulum = partial resorption of vitelline duct/ failure of closure on side of the lumen* *Vitelline fistula = no resorption of vitelline duct* *Omphalomesenteric cyst = both ends of vitelline duct inovlute (leaves a persistent cavity)
Why is yogurt not removed from diet in lactose intolerance?
Yogurt that is made with live bacterial cultures is OK because when it enters the intestine the bacteria will convert lactose to lactic acid and therefore it's better tolerated. Yogurt that is not made with live bacterial culture (such as frozen yogurt) is still not good for people with lactose intolerance.
Tropical Sprue commonly occurs after?
after an acute infectious diarrheal illness
Adhesions
fibrous bands that form between tissues and organs, and are most commonly a result of injury during surgery. Adhesions can also occur with any intraabdominal process such as fistula's related to Crohns and diverticulitis with perforation.
Ischemic bowel disease
http://www.score95.com/blog/blog/usmle-ischemic-bowel-disease/ *****
http://www.usmleforum.com/files/forum/2008/1/319707.php
http://www.usmleforum.com/files/forum/2008/1/319707.php
https://quizlet.com/21814456/small-bowel-disease-2-malabsorption-flash-cards/
https://quizlet.com/21814456/small-bowel-disease-2-malabsorption-flash-cards/
