Osmosis Dermatology

A woman presents to a dermatologist because she has lost almost all the hair on her body, including scalp hair, eye brows, eye lashes, arm pit and groin hair, and the fine hairs on her body and extremities. She most likely has a variant of which of the following? A. Alopecia areata BAndrogenic alopecia CChronic cutaneous lupus erythematosus DLichen planopilaris ETrichotillomania

A. Alopecia areata Main Explanation Alopecia areata is caused by an autoimmune attack on hair follicles. It has a wide range of clinical severity, with most cases involving a localized patch of hair (which regrows within 1 year in half of the patients). The hair that does regrow may be gray or depigmented. More severe cases can involve the entire scalp (alopecia totalis) or, as in this patient, the entire body surface (alopecia universalis). These more severe cases are less likely to resolve adequately. Treatment of alopecia areata is often unsuccessful, but topical steroids are typically tried. Androgenic alopecia (choice B) is common male pattern baldness. Chronic cutaneous lupus erythematosus (choice C) can produce localized baldness. Lichen planopilaris (choice D) can produce localized baldness. Trichotillomania (choice E), also called traumatic alopecia, is alopecia due to trauma, such as hair pulling or tight braids.

Which type of eczema is usually associated with asthma, allergic rhinitis and IgE-mediated systemic manifestations? A. Atopic dermatitis BContact dermatitis CNummular eczema DDyshydrotic eczema EAsteatotic dermatitis

A. Atopic dermatitis Main Explanation Atopic dermatitis is most often associated with allergic reactions and asthma.

Which type of vascular malformation presents with a "port wine stain"? A. Capillary malformation B. Venous malformation C. Lymphatic malformation D. Arteriovenous malformation

A. Capillary malformation Main Explanation A port-wine stain is a birthmark, nevus flammeus, caused by swollen blood vessels that create a reddish-purplish discoloration of the skin. It may rarely be a sign of Sturge-Weber Syndrome (SWS), a rare congenital neurological and skin disorder caused by a capillary malformation (CM) across the ### opthalmic nerve (V1) in the face. A relatively high percentage (10-15) of infants with V1 CM will have Sturge-Weber Syndrome. A famous person with the port-wine stain capillary malformation is Mikhail Gorbachev, the first and last president of the Soviet Union. He has a prominent capillary malformation on his forehead.

Raised yellowish brown collections of serum and inflammatory cells which are well circumscribed on the skin can be best described as: A. Crusts BScales CPurpura DPlaques

A. Crusts Main Explanation Crusts are yellow-brown to black, circumscribed collections of serum and inflammatory cells that can be mixed with epithelial cells and bacterial debris on the cell surface. Scales, in comparison, are white to brown flakes on the skin that represent thicker keratinized masses.

A patient presents to your clinic with a clearly evident fungal infection of his skin. You correctly diagnose him with tinea versicolor. Which of the following fungi is the most likely cause? AMalassezia BTrichophyton rubrum CTrichophyton interdigitale DCandida albicans

A. Malassezia Formerly known as Pityrosporum, Malassezia is a genus of fungi naturally found on skin surfaces of humans that can occasionally cause an opportunistic infection leading to hypopigmentation. It is the most common cause of dandruff and seborrhoeic dermatitis and also can lead to tinea versicolor (skin rash). The image shows yeast-like fungal cells of Malassezia furfur in skin scale.

What type of skin lesion is elevated, filled with inflammatory cells, and exudes a "yellow-white material" when it is punctured? A. Pustule B. Purpura C. Papule D. Vesicle

A. Pustule Main Explanation Pustules are very similar to vesicles except that they have been filled with inflammatory cells causing the characteristic clear fluid of vesicles to instead be a yellow-white exudate of pus.

A 25 year old with pale hair and skin presents to his primary care physician with multiple sun burns over his face and extreme photo-sensitivity. Which of the following accurately describes the pathology of his condition? AOverproduction of melanocytes BDestruction of melanocytes CDecreased melanin DExcess melanin

AOverproduction of melanocytes Melanoma - a neoplasm of melanocytes, characterized clinically by the ABCDE's A: Asymmetry B: Border irregularity C: Color variation D: Diameter >6mm (or increasing) E: Elevation off the skin surface BDestruction of melanocytes Vitiligo - A chronic depigmenting skin condition thought to be caused by destruction of melanocytes (not loss of melanin). Associated with diabetes mellitus, hypothyroidism, pernicious anemia, and Addison's disease CDecreased melanin Albinism - A condition caused by a decreased production of melanin leading to a lack of color in the hair and skin. Some of the ocular findings are caused by a poorly developed retinal pigment epithelium (RPE) due to the absence of melanin. Treatment consists of visual rehabilitation, possible surgical eye correction, sun burn prevention, and frequent skin checks. DExcess melanin Freckle (Nevus) - a common benign condition in light skinned persons

The most accurate term describing a lesion that has a diameter greater than 1 cm, is raised from the skin, contains no fluid, and is irregularly shaped is: APlaque BMacule CVesicle DPapule

APlaque Main Explanation While all plaques are types of papules, the most accurate description for a papule with a diameter greater than 1 cm is a plaque. While this may be a small detail, it is important to know the difference.

A patient presents with the following lesions caused by poxvirus. What is the likely diagnosis? A. Molluscum contagiosum B. Hemangioma C. Morphea D. Klippel-Trenaunay syndrome

Answer: (A) Molluscum contagiosum Main Explanation Molluscum contagiosum is a viral infection of the skin or sometimes mucous membranes, also called water warts. It's caused by the molluscum contagiosum virus (MCV), which is a DNA poxvirus. B. Hemangioma is Incorrect: Hemangiomas are benign and usually self-involuting tumors of endothelial cells that line blood vessels. These usually appear within the first weeks of life and resolve by age 10. C. Morphea is Incorrect: Morphea is a localized or circumscribed scleroderma characterized by asymmetrical, rock-hard lesions. D. Klippel-Trenaunay syndrome is Inocorrect: KTS is a rare congenital medical condition in which blood vessels and/or lymph vessels fail to form properly. The three characteristic features are: venous and lymphatic malformations, soft-tissue hypertrophy of the affected limb, and nevus flammeus (port-wine stain).

A 44 year old female presents with reddened, inflamed patches with a flaky silver-white layer on her left knee. You, as the physician, diagnosed the condition with psoriasis. What is the underlining cause of this condition? A. A defect in the keratinocyte intermediate filaments B. An increase in mitotic activity of the cells in the malpighian layer of the epidermis C. Exposure of unprotected skin to UV light D. Squamous cell carcinoma arising from cells of the stratum spinosum E. None of the above

B. An increase in mitotic activity of the cells in the malpighian layer of the epidermis Main Explanation Psoriasis is a skin condition in which increase in mitotic activity of the cells in the malpighian layer of the epidermis that have shorter than normal cell cycle. Redness is due to an increase of blood flow to nourish the accelerated growth. (A) suggests Epidermolysis bullosa. (C) is indicative of skin damage due to radiation. (D) Skin cancer has no association with psoriasis.

A 20 year old woman with inflammatory bowel disease presents with a new rash on her legs. The rash appeared 2 days ago and is tender to touch. Which condition does she most likely have, and what is the name of this rash? A. Crohns disease, dermatitis herpetiformis B. Crohns disease, erythema nodosum C. Crohns disease, erythema chronicum migrans D. Ulcerative colitis, dermatitis herpetiformis E. Ulcerative colitis, erythema nodosum F. Ulcerative colitis, erythema chronicum migrans

B. Crohns disease, erythema nodosum Main Explanation Erythema nodosum (EN) is an acute, nodular, erythematous eruption that usually presents on the extensor aspects of the lower legs bilaterally. It is caused by inflammation of subcutaneous fat, resulting to tenderness to palpation. This rash can be caused by a variety of conditions, however inflammatory bowel disease - particularly Crohns disease (CD) - have been associated. Cutaneous symptoms of CD usually present 3-7 years after the onset of GI symptoms, and is controlled by managing the underlying enteropathy.

A 50-year old African American male presents to your clinic with scaly lesions and scars on his face. These lesions lack hair follicles and sweat glands. Which of the following disease does this patient most likely have? A. Vitiligo B. Discoid lupus erythematosus C. Sarcoidosis D. Pseudofolliculitis barbae E. Acne keloidalis F. Cicatricial alopecia Discoid lupus erythematosus (DLE) is a chronic skin condition of sores with inflammation and scarring often on the face, ears, and scalp. The lesions develop as red, inflamed patches with scaling.

B. Discoid lupus erythematosus Explain All of these diseases are generally worse in darker skinned patients. Discoid lupus erythematosus (DLE) is a chronic skin condition of sores with inflammation and scarring often on the face, ears, and scalp. The lesions develop as red, inflamed patches with scaling. Depigmentation caused by T cell destruction of melanocytes causes vitiligo Sarcoidosis: Waxy plaques on the eyes, nose, and ears. Lung complications are common in over 90 percent of patients presenting with some form of abnormal chest X-ray. Lupus pernio (image) in particular presents with lesions beneath the nose and is very likely to cause severe lung complications. Ingrown hairs and irritation from shaving occurs in Pseudofolliculitis barbae. Destructive scarring folliculitis which occurs on the back of the head ocurrs in Acne keloidalis. Destructive folliculitis which occurs almost exclusively in African-American patients and is characterized by destruction of the inner root sheath of the follicle.

A researcher is investigating epithelial cell junctions. She injects one cell with a liquid dye and notes that the dye seeps into the adjacent cell. Which epithelial cell junction is most likely to have allowed the dye through to the adjacent cell? A. Desmosome B. Gap junction C. Hemidesmosome D. Zona adherens E. Zona occludens

B. Gap junction Main Explanation Gap junctions (choice B) allow adjacent cells to communicate with one another. They are made up of connections with central channels which allow small substances ## (< 1000 daltons) to pass between cells. Desmosome (choice A), also known as a macula adherens, is a discrete site of attachment between cells that stabilizes the cell to cell connection; however, it does not allow any substance to pass between the cells. Hemidesmosomes (choice C) attach the cell to its underlying extracellular matrix and are not involved in cell to cell communication. Zona adherens (choice D) is made up of ## actin filaments and E-cadherin and participates in stabilizing the border between cells. It does not allow communication between cells. Zona occludens (choice E) is a tight junction between cells that prevents substances from diffusing across the intracellular space. From basal surface: hemidesmosomes (ECM/basement membrane) → zona adherens → macula adherens → zona occludens/tight junction

A blister that is umbilicated in the center, raised in the periphery, and contains clear fluid is indicative of what virus? A. Influenza B. Herpes C. HIV D. Rubella

B. Herpes Herpes viruses (all types) are characterized by blister-like lesions with umbilicated centers and clear fluid in the annular region surrounding the center.

Which of the following is a type of firm, rubbery scar or fibrous nodule which is composed mainly of either type III (early in formation) or type I (late in formation) collagen resulting from overgrowth of granulation tissue? A. Nevus B. Keloid C. Comedones D. Sclerodactyly

B. Keloid A keloid is a type of firm, rubbery scar or fibrous nodule which is composed mainly of either type III (early in formation) or type I (late in formation) collagen resulting from overgrowth of granulation tissue

The hands in the pictures below depict Raynaud's phenomenon. Which of the following disorders is associated with this? A. Diffuse scleroderma B. Limited cutaneous scleroderma C. Capillary malformation D. Painter's problem

B. Limited cutaneous scleroderma Main Explanation Limited cutaneous scleroderma (LcSSc) is also known as CREST syndrome: Calcinosis, Raynaud's Syndrome, Esophageal dysmotility, Sclerodactyly, Telangiectasia. Raynaud's occurs because of exaggerated vasomotor response to cold or emotional stress. ## Hyperactivation of the sympathetic nervous system causes extreme vasoconstriction of the peripheral blood vessels and subsequent tissue hypoxia. - Chronic and recurrent cases of Raynaud's can lead to atrophy and, in extreme cases, ulceration and even gangrene. A. Diffuse scleroderma Rapidly progressing scleroderma that affects both the skin and one or more of the internal organs, such as the heart, lungs, esophagus, and kidneys. C. Capillary malformation CM is characterized by a "port wine stain" D.Painter's problem Fictionalized problem because Raynaud's looks like the hand was dipped in paint.

A 46-year old Hispanic male from Arizona presents to your dermatology clinic with painful lesions in his mouth that have since spread to his entire body. Further testing and genetic screening confirm what you had originally suspected: the patient expresses a DR4 gene commonly seen in Ashkenazi Jews. Which disease is at the top of your differential? A. Epidermolysis bullosa B. Pemphigus vulgaris C. Ehlers-Danlos syndrome D. Bullous pemphigoid E. Pemphigus foliaceus

B. Pemphigus vulgaris Main Explanation Pemphigus vulgaris is characterized by painful oral lesions that progress to skin lesions later on. Peak incidence occurs at around 50 years of age and there is a much higher prevalence in Ashkenazi Jews (due to the presence of predisposing genes such as DRB1*0402, a type of DR4 HLA). This same prevalence is seen in the Hispanic population of the American Southwest as well (due to the integration of ethnic Jewish into the Hispanic community following the Spanish Inquisition)

In 1873 the famous English political philosopher John Stuart Mill died from the same disease seen in the image below. It appears as an erythematous rash that's swollen, hard, and painful. Other symptoms include fevers, shaking chills, headache, and vomiting. What disease is this? A. Impetigo B. Tinea Versicolor C. Erysipelas D. Intertrigo

C. Erysipelas Main Explanation Also known as St. Elmo's Fire, erysipelas is a subtype of cellulitis that predominantly affects the face. It is caused by an invasive, acute streptococcal (typically Group A) infection in the deep epidermis and fat that spreads through the lymphatics. Common symptoms include:blisters; fever; shaking; chills; skin lesions with a raised border; painful, bright red, swollen, and warm skin underneath the lesion; sores on the cheeks and bridge of the nose.

A 62-year old man presents to his primary care physician complaining of a recent eruption of blisters all over his body. On exam, the patient has multiple tense bullae in his axillae, groin and in flexural areas of his arms bilaterally as seen in the accompanying image. His oral exam reveals pink mucosa with no lesions. The physician takes a punch biopsy at the site of one of the blisters, which demonstrates deposits of IgG and complement along the basement membrane of the epidermis. This patient's symptoms likely represent an autoimmune reaction targeting which of the following structures? A. Desmosome B. Hair Follicle C. Hemidesmosome D. Melanocyte E. Pacinian corpuscle

C. Hemidesmosome Main Explanation This patient has bullous pemphigoid, an autoimmune blistering disorder. In this disease, autoantibodies are formed against basement membrane hemidesmosome proteins. The hemidesmosome is a specialized structure that anchors cells to the extracellular matrix; in the skin, hemidesmosomes attach keratinocytes to the basement membrane. The destruction of hemidesmosomes in bullous pemphigoid results in the formation of subepidermal blisters or "tense bullae" as opposed to the flaccid bullae seen with pemphigus vulgaris. On punch biopsy, a characteristic deposition of IgG and complement can be seen along the basement membrane. A. Proteins in the desmosome are targeted in the autoimmune blistering disorder known as pemphigus vulgaris. The desmosome is a specialized structure which anchors cells to each other within the epidermis so that disruption of the desmosome results in intraepidermal blistering and flaccid bullae. ## Pemphigus vulgaris often begins with lesions in the oropharynx (recall that this patient had a normal oral exam), which then spread to the skin preferentially affecting the scalp, face, axillae and groin. Nearly all patients have oral lesions at some point during their disease. Skin biopsy shows deposits of IgG between epidermal cells. B. An antigen in the hair follicle is thought to be the target of autoantibodies in alopecia areata but the precise antigen has yet to be identified. D. The melanocyte is thought to be the target of autoantibodies in vitiligo. E. The Pacinian corpuscle is a mechanoreceptor in the skin primarily responsible for sensing deep touch and vibration. It is not a target for autoimmune disease. Many drugs have been recognized to induce BP, including furosemide, bumetanide, spironolactone, phenacetin, penicillins, ibuprofen, D-penicillamine, captopril, fluoxetine, β-adrenergic blockers, terbinafine, gabapentin, risperidone, and PUVA. The clinical hallmarks of the eruption are tense bullae with either generalized or localized distribution. Mucosal involvement with small blisters or erosions may exist in a minority of patients. Although there can be relapses and exacerbations, BP is generally self-limiting, with remission in most adults by 5 years, and more rapidly in children.

Which of the following is a localized or circumscribed scleroderma characterized by asymmetrical, rock-hard lesions that are mostly harmless unless found in the joints in which case they may cause contracture and growth reduction? A. Hemangioma B. Molluscum contagiosum C. Morphea D. Klippel-Trenaunay syndrome

C. Morphea Morphea is a localized or circumscribed scleroderma characterized by asymmetrical, rock-hard lesions. A. Hemangioma Hemangiomas are benign and usually self-involuting tumors of endothelial cells that line blood vessels. These usually appear within the first weeks of life and resolve by age 10. B. Molluscum contagiosum Molluscum contagiosum is a viral infection of the skin or sometimes mucous membranes, also called water warts. It's caused by the molluscum contagiosum virus (MCV), which is a DNA poxvirus. D. Klippel-Trenaunay syndrome KTS is a rare congenital medical condition in which blood vessels and/or lymph vessels fail to form properly. The three characteristic features are: venous and lymphatic malformations, soft-tissue hypertrophy of the affected limb, and nevus flammeus (port-wine stain). If there is an associated AVM, the disorder is called Klippel-Trenaunay-Weber syndrome (KTW).

Which of the following types of eczema is associated with coin-shaped plaques composed of grouped small papules and vesicles on an erythematous base? AContact Dermatitis BAtopic Dermatitis C. Nummular Eczema DDyshidrotic Eczematous Dermatitis

C. Nummular Eczema Main Explanation Nummular eczema is also characterized by chronic, pruritic (itchy), inflammatory dermatitis and is most commonly found on the lower legs during the winter months. "Nummular" means "coin" in Latin, which you can remember by thinking of "number".

A 20 year old man presents to the office complaining of multiple "skin spots" that are scattered across his back, as shown in the image. He states that he has had them for years, but they are now more numerous and noticeable. Physical exam reveals scoliosis of the back. Slit lamp examination of the eye reveals several small papules on the iris. In consideration of this patient's most likely diagnosis, what is he at greatest risk of developing? A. Cardiac rhabdomyoma B. Pectus excavatum C. Pheochromocytoma D. Renal angiomyolipoma E. Renal cell carcinoma

C. Pheochromocytoma Main Explanation This patient presents with classic symptoms of neufibromatosis type I (NF1), also known as von Recklinghausen's disease. The "skin spots" shown on the back are neurofibromas and can be few or many in number depending on the patient. Scoliosis is one of many skeletal phenomena that can be present in NF1 patients. The small papules present on the iris are Lisch nodules; they are hamartomas pathognomonic of NF1 that ## do not interfere with vision. Additional signs include cafe au lait spots, peripheral nerve masses that can occur along the route of any peripheral nerve, and gliomas anywhere in the CNS. This patient is most at risk to develop a pheochromocytoma with concurrent hypertension. As a final note, NF1 is of autosomal dominant inheritance, with the mutated gene located on chromosome 17. To learn more, ask about the family history. Cardiac rhabdomyomas (choice A) are congenital heart tumors that occur in over ## 50% of patients with tuberous sclerosis, a genetic syndrome characterized by cutaneous lesions, seizures, hamartomas, and mental retardation. Pectus excavatum (choice B) is a congenital rib and sternal deformity characterized by a sunken anterior chest wall. It can predispose to cardiac and respiratory malfunction. The genetic condition with which it is most commonly associated is a. Marfan syndrome, a disorder of fibrillin synthesis that leads to various skeletal abnormalities including arachnodactyly, and cardiac abnormalities including mitral valve prolapse. Renal angiomyolipomas (choice D) are benign tumors comprised of vascular elements, smooth muscle, and adipose tissue. They may occur as one of the manifestations of tuberous sclerosis (see above). Renal cell carcinoma (RCC, choice E) is the most common type of renal cancer often characterized by the triad of flank pain, abdominal mass, and hematuria. 50% of patients with von Hippel-Lindau disease (VHL) develop bilateral RCC. VHL is a multi-system vascular disorder consisting of hemangioblastomas of the CNS in addition to extra-neural tumors and cysts occurring throughout the body.

A 64-year-old man with a history of squamous cell carcinoma of the head and neck presents to your office for follow up after undergoing several cycles of radiation therapy. He notes that his dentist just told him he has several cavities, although he has never had cavities before. He also noticed that his food often has a "metallic" taste. On exam, you note that he has dry oral mucosa. Which medication may be helpful for this patient? A. Dicyclomine B. Scopolamine C. Pilocarpine D. Atropine E. None of the above

C. Pilocarpine Main Explanation Patients who undergo head and neck radiation can develop xerostomia (dry mouth). Actor Michael Douglas underwent radiation for head and neck cancer and developed xerostomia. The symptoms of xerostomia go beyond just having a dry mouth. Patients may develop cavities, oral candidiasis, trouble swallowing (especially dry foods), halitosis, and thirst. Many of these are due to the fact that saliva is more than a lubricant and when there is damage to the salivary glands from radiation, they may produce far less or even no saliva. The only FDA approved agent to treat xerostomia is pilocarpine, a parasympathomimetic alkaloid and non-selective muscarinic receptor agonist. It has the opposite effect of anticholinergic medications, like atropine, dicyclomine and scopolamine. Remember anticholinergic effects as: Hot as a hare (hyperthermia) Blind as a bat (dilated pupils) Dry as a bone (dry skin) Red as a beet (vasodilation) Mad as a hatter (hallucinations/agitation) The bowel and bladder lose their tone and the heart goes on alone (ileus, urinary retention, tachycardia) A. Dicyclomine This is a muscarinic antagonist used in the treatment of irritable bowel syndrome. Therefore it can cause anticholinergic side effects like dry mouth. B. Scopolamine This is an anti-nausea medication and has anticholinergic side effects. D. Atropine This is an anticholinergic drug used in anesthesia and also in symptomatic bradycardia. Therefore it can cause anticholinergic side effects like dry mouth.

A 73-year old woman has a 1 cm, scaly, raised lesion on the right side of the face. A photomicrograph of tissue obtained on biopsy of the excised lesion is shown. Use which of the following is most likely to have prevented the development of this lesion. A. Conjugated Estrogen B. Isoniazid C. Sunscreen D. Tretinoin cream E. Triamcinolone cream

C. Sunscreen Main Explanation Correct answer is C. Sunscreen. The patient has Squamous Cell Carcinoma of the skin. Prevention involves the use of high-quality sunscreens, preferably with SPF (sun protection factor) ratings of at least 30. Option A. Conjugated Estrogen is wrong because conjugated estrogens (e.g. Premarin) are commonly used for treating the symptoms of menopause including hot flashes, vaginal dryness, and vaginal atrophy. Option B. Isoniazid is wrong because Isoniazid is the first-line antituberculosis medication in prevention and treatment. Option D. Tretinoin cream is wrong because this cream is commonly used to improve the appearance of the skin by reducing fine lines and wrinkles, reducing roughness and improving coloration and can also be used to treat acne. Option E. Triamcinolone cream is wrong because this cream is not used to prevent squamous cell carcinoma, it is commonly used in the post-operative period of certain cosmetic surgery procedures, notably ## rhinoplasty. Injected into the subcutaneous area, it may help to alleviate stubborn swelling, inflamed sebaceous cysts, and scar tissue. Other used are to treat keratosis pilaris, psoriasis, oral irritation after dental procedures. It is highly effective in the most severe cases of eczema, but may require a waiting period before subsequent treatments.

A 31 year old female presents with scaly patches of skin on her legs that seem worse during the winter months. She has suffered with these skin lesions on and off for most of her life, but this is the first time she has mentioned the problem to her doctor. Physical exam reveals areas of erythema with overlying silver scaling. Removal of the scale causes pinpoint bleeding. What is the first line therapy for this condition? A. Ultraviolet light B. Actiretin C. Topical corticosteroids D. Cyclosporine

C. Topical corticosteroids These are the most common first line agents used in psoriasis treatment. Main Explanation Psoriasis is a dermatological condition caused by accelerated proliferation of skin cells, leading to defective keratinization, and thus scaling. The disease is chronic, but classically comes with flares and remissions, resulting in well-delineated erythematous plaques with thick scaling. Auspitz's sign - removal of the scale causes bleeding. Treatment of the disease is by a step-wise progression of therapy, as shown above. First line therapy generally involves topically corticosteroid creams. B. Acitretin A systemic retinoid therapy reserved for later in the course of psoriasis treatment. A. Ultravoilet light UV light has been shown to be highly effective in some patients, and can be combined with other treatment options. Nevertheless, it is not a first line agent at this point. Many psoriasis patients have fewer plaques during the summer months, likely due to the suns UV rays.

A 25-year old female patient with AIDS presents to your clinic with a clearly evident fungal infection of her mouth. Which of the following fungi is the most likely cause? A. Malassezia B. Trichophyton rubrum C. Trichophyton interdigitale D. Candida albicans

D. Candida albicans C. albicans is a # diploid fungus that is known for opportunistic oral and genital infections, particularly in immunocompromised patients with AIDS or undergoing chemotherapy. It can cause oropharyngeal candidiasis, or thrush, as well as vulvovaginal candidiasis. A. Malassezia Formerly known as Pityrosporum, Malassezia is a genus of fungi naturally found on skin surfaces of humans that can occasionally cause an opportunistic infection leading to hypopigmentation. It is the most common cause of dandruff and seborrhoeic dermatitis and also can lead to tinea versicolor (skin rash). The image shows yeast-like fungal cells of Malassezia furfur in skin scale. B. Trichophyton rubrum T. rubrum is the most common cause of Tinea pedis (Athlete's foot), Tinea cruris (jock itch), and dermatophytosis (ringworm). C. Trichophyton interdigitale One of three common fungi that cause ringworm and the second most commonly isolated fungus causing tinea infections in humans. It is one of the most common fungus causing zoonotic skin disease, with a major natural reservoir in rodents. D. Candida albicans C. albicans is a diploid fungus that is known for opportunistic oral and genital infections, particularly in immunocompromised patients with AIDS or undergoing chemotherapy. It can cause oropharyngeal candidiasis, or thrush, as well as vulvovaginal candidiasis.

A 62-year-old male actor comes to the physician three days after he noticed a lesion on his nose. He was on set and when he scratched his nose, he thought he had removed a scab because it was bleeding. However, his makeup artist was concerned and suggested he go to the doctor. In addition to being an actor, the man is an avid mountain climber and loves spending hours climbing in the sun. Examination of his nose reveals a 3 mm erythematous area that is pearly and slightly raised. Biopsy is performed and histology suggests basal cell carcinoma, superficial type. Which of the following treatments should the patient receive? A. Topical chemotherapy B. Cryotherapy C. Mohs surgery D. Electrodesiccation and curettage (ED&C) E. None of the above

D. Electrodesiccation and curettage (ED&C) Both the appearance of the lesion (pink, pearly raised nodule) as well as the fact that he gets a lot of sun exposure (mountain climbing) both support the diagnose of BCC. The key to this question is that the BCC is low-risk. All of the above therapies are used for BCC, but the best one for a low-risk BCC is ED&C. A. Topical chemotherapy This is less frequent used for low-risk BCC. B. Cryotherapy This is less frequently used for low-risk BCC. C. Mohs surgery In Mohs surgery, the BCC is removed and margins are repeatedly examined until they are clean. It is costly and requires a lot of time. It is not usually indicated for a low-risk BCC. D. Electrodesiccation and curettage (ED&C) ED&C is indicated for BCC lesions that are deemed to be low risk. A BCC is considered low risk based on i) location/size (<6mm in high risk areas like the face, nose, eyelids, eyebrows, etc) ii) pathology (nodular or superficial pattern) iii) recurrence (a primary lesion is low-risk), and iv) some other factors (a low-risk patient has not had radiation at the site of the BCC and is immunocompetent). This image shows a superficial BCC, which is also suggested by his exam (a reddish area that is slightly raised).

A 72-year-old man presents with large, tense, pruritic bullae on the lower abdomen, groin, and inner thighs. Skin biopsy reveals IgG antibodies with linear immunofluorescence at the epidermal basement membrane. To what cell junctions are the antibodies binding? A. Adherens junctions B. Desmosomes C. Gap junctions D. Hemidesmosomes E. Tight junctions

D. Hemidesmosomes Main Explanation This man's clinical presentation suggests bullous pemphigoid, which is an autoimmune disorder with IgG antibody against epidermal basement membrane hemidesmosomes (choice D). This disorder is similar, but not as severe as pemphigus vulgarus, which affects desmosomes (choice B). Pemphigus vulgaris usually affects the oral mucosa as well, while bullous pemphigoid mostly spares the oral mucosa. Adherens junctions (choice A), gap junctions (choice C), and tight junctions (choice E) are other cell junctions that are not involved in bullous pemphigoid. To maintain the structure and function of the epidermis a number of intercellular junctions exist, including tight junctions, gap junctions, adherens junctions, and desmosomes. The principal structural protein of tight junctions are the claudins, of which there are approximately 24 subtypes. Apart from the kidney, tight junctions have key roles in other organs, including the ear and liver. dermatologic manifestations of inherited tight junction mutations are limited to genetic disorders of claudin 1. neonatal ichthyosis and sclerosing cholangitis - defect in Claudin 1 gene.

A 21-year old female presents with a sclerotic plaque that has furrowed in the frontal scalp. She has no other issues. What is the most likely diagnosis? A. Plaque morphea B. Keloid C. Limited cutaneous scleroderma D. Linear morphea

D. Linear morphea Main Explanation This is classic morphea en coup de sabre, a type of linear morphea, named for its perceived similarity to a sabre wound. Morphea is localized scleroderma

Which form of psoriasis is characterized by discrete, erythematous, scaly papules and plaques, and is commonly found on the elbows, knees, presacrum and scalp? A. Inverse/Flexural psoriasis B. Psoriatic arthritis C. Guttate psoraiasis D. Plaque psoriasis

D. Plaque psoriasis Psoriasis is an immune-mediated disease that is generally a lifelong condition. The word "psoriasis" derives from the Greek language and roughly means "itching condition" (psora "itch" + -sis "action, condition"). In plaque psoriasis, rapid skin accumulation leads to a silvery-white appearance. As opposed to eczema, psoriasis is more likely to be found on the outer side of the joint. A. Inverse/ Flexural psoriasis Found in the axillae, inguinal crease, intergluteal cleft, inframammary and retroauricular areas of the body B. Psoriatic arthritis This is usually associated with rheumatoid-arthritis-like symptoms in hand joints C. Guttate psoraiasis Usually characterized by small papules and plaques D. Plaque psoriasis Characterized by discrete, erythematous, scaly papules and plaques, and is commonly found on the elbows, knees, presacrum and scalp

A 25-year old black male comes to your clinic with multiple hyperpigmented papules on his neck. Which of the following is the most likely diagnosis? ACentral centrifugal cicatrical alopecia (CCCA) BSarcoidosis CAcne keloidalis D. Pseudofolliculitis barbae (PFB)

D. Pseudofolliculitis barbae (PFB) Main Explanation Also known as barber's itch, razor bumps, folliculitis barbae traumatica, and shave bumps, PFB is a medical term for persistent irritation caused by shaving. Curvy hair tends to lead to PFB because after the tip of the hair shaft is cut, it may regrow into the skin causing the irritation. Most cases can be resolved by letting the hair grow out. Most common in adolescents and young adults, acne keloidalis nuchae is a destructive scarring folliculitis that occurs mainly on the occipital scalp of people of African descent (primarily men). A. Central centrifugal cicatrical alopecia (CCCA) Most often seen in African Americans, CCCA is also known as follicular degeneration syndrome and is currently thought to be a result of styling techniques such as relaxers, heavy extensions, tight braids, oils, and gels.

Rheumatoid vasculitis is often associated with purplish-red discolorations that appear on the skin. You apply pressure to these lesions and they fail to blanch. This indicates that these discolorations are most likely which of the following? APlaques BAtrophy CBullae D. Purpura

D. Purpura Main Explanation Purpura are characteristically reddish-purple discolorations that appear in certain disorders such as rheumatoid vasculitis. They are caused by the blood leaking out of damaged vessels. This is the reason that occluding the vessels by applying pressure does not result in blanching, or turning white. Purpura are usually a result of vasculitis or dietary deficiency of vitamin C (scurvy). They are distinguished from petechiae and ecchymoses by their size. Petechiae are less than 3 mm, purpura are 3-10 mm, and ecchymoses are larger than 10 mm.

A 21 year old man goes to his primary care doctor after experiencing dry, scaly skin for several months. He has patches of red, thickened skin with areas of silver scaling over his elbows, knees, and scalp. He has had some itching at those areas but over-the-counter lotion use has not helped much. A picture of his rash is shown. Histological examination of one of the lesions would most likely show increased thickness in which of the following layers of in the photo? A. Stratum corneum B.Stratum lucidum C. Stratum granulosum D. Stratum spinosum E. Stratum basale

D. Stratum spinosum Main Explanation The stratum spinosum is often increased in thickness in psoriasis, as this individual most likely has based on clinical description. A. Stratum corneum: Histological examination of this layer in psoriasis will show ## parakeratotic scaling in which nuclei are still present. Normal stratum corneum should not have nuclei. This layer also will show ## hyperplasia (acanthosis). Neutrophil collections called Munro ## microabscesses can be found in this layer with psoriasis. C: The stratum granulosum is ## decreased in size in psoriasis. E: In psoriasis histology shows ## extension of rete pegs, which are downward extensions of the basale layer into the dermis.

A 22-year-old college student presents to Student Health during his final exams complaining of a painful, vesicular lesion on his upper lip as seen in the accompanying image. He gives a history of having had similar lesions in the past in the same location. What type of organism is most likely responsible for the student's symptoms? A. A single-stranded RNA virus B. A double-stranded RNA virus C. A double stranded non-enveloped DNA virus D. A single-stranded non-enveloped DNA virus E. A double-stranded enveloped DNA virus

E. A double-stranded enveloped DNA virus Main Explanation The lesion seen in the photo represents herpes labialis from infection with herpes simplex type I infection (HSV- I). HSV-I is part of the herpesviridae family and is an enveloped double-stranded DNA virus. Other members of the herpesviridae family include herpes simplex type II (HSV-II), Varicella-Zoster virus, Epstein-Barr virus, and cytomegalovirus. The virus remains latent in the trigeminal root ganglion and reactivation is provoked by stress or illness resulting characteristically in lesions in the same location as previous outbreaks. A. Most RNA viruses are single-stranded including the families calicivirus (Norwalk), picornavirus (polio, enteroviruses, hepatitis A), flavivirus (yellow fever, hepatitis C), togavirus (rubella). B. An example of a double-stranded RNA virus is rotavirus, the most common cause of acute viral gastroenteritis in infants and children. C. Double stranded naked DNA virus include adenovirus. Adeno viruses are nonenveloped viruses with an icosahedral protein capsid. Adenovirus serotypes 11 & 21 are associated with hemorrhagic cystitis in child care. Adenovirus serotypes 4 & 7 use to be provided to the military recruits as vaccines. Increase incidence of adenovirus occurs with military recruits and day care centers. AdV can be shed from the gastrointestinal tract for prolonged periods and can establish chronic low-level infection of the tonsils and adenoids. D. An example of a single-stranded DNA virus is parvovirus B19. This agent causes erythema infectiosum (Fifth disease) in children and is linked to aplastic crises in sickle cell anemia patients. All other DNA viruses are double stranded.

In bullous pemphigoid, auto-antibodies are made against which of the following? AKeratin BDesmosomes CFibrin DType I Collagen EHemidesmosomes

E. Hemidesmosomes Main Explanation Bullous pemphigoid most often affects the elderly and is characterized by blistering skin. In bullous pemphigoid, auto-antibodies are made against components of the hemidesmosomes, resulting in ## subepidermal separation. These auto-antibodies are directed against either BP230 (which is a hemidesmosome) OR BP180 (which is termed type XVII collagen).

A 35-year old Caucasian female presents to the hospital with very painful superficial cutaneous lesions over her body. At first you begin treatment for a staphylococcal infection, but the vancomycin regimen is ineffective. What disease have you mistakenly treated as a staph infection? A. Epidermolysis bullosa B. Pemphigus vulgaris C. Ehlers-Danlos syndrome D. Bullous pemphigoid E. Pemphigus foliaceus

E. Pemphigus foliaceus Main Explanation Pemphigus foliaceus is an autoimmune disease that only affects Desmoglein 1 (DsG1). As a result, only superficial cutaneous blistering is seen (no oral lesions). Staphylococcal Scalded Skin Syndrome (SSSS) presents with the exact same phenotype as pemphigus foliaceus because of a bacterial exotoxin that targets DsG1 in the same manner as the autoantibodies of pemphigus foliaceus.

A 75 year old male professional golfer presents to his physician with a lesion on the lateral aspect of his nose that has been present for several months. When questioned about sun exposure he states during his playing career he rarely wore a hat or sunscreen. On exam, the lesion is papular with rolled edges and appears pearly. This lesion most likely arose from which of the following? A.stratum corneum B. melanocytes C. stratum granulosum D. stratum spinosum E. stratum basale

E. stratum basale The patient most likely has basal cell carcinoma as a result of many years of unprotected sun exposure. BCC is the most common skin cancer and arises from the basal layer of cells in the epidermis. It is common is sun exposed regions such as the head and neck. It is typically described as a pearly, smooth papule with ## rolled edges and surface telangiectasias. Metastasis is rare but it can be locally destructive. Choice A (stratum corneum) consists of keratinized, dead cells and contain no nuclei. It is not the source of basal cell carcinoma. Choice B (melanocytes) are the source of melanoma. This is an aggressive skin cancer and ## number one cause of skin cancer death. Features of melanoma include asymmetry, border irregularity, color variation-pink to black to blue, >5mm in diameter, elevated (ABCDE). Choice C (stratum granulosum) are where keratin proteins and water-proofing lipids are produced and organized. It is not the source of basal cell carcinoma. Choice D (stratum spinosum) is where ## keratinization begins. This layer is not the source of basal cell carcinoma but can ## increase in size in psoriasis. The second most common cause of skin cancer is squamous cell carcinoma. It arises from epidermal cells undergoing keratinization but is ## not associated with any particular layer. Sunlight is the most important risk. Typically it is a crusting, ulcerated nodule or erosion.

Which of the following choices most accurately represents the cell types of the epidermis in order of increasing relative abundance? A. Melanocytes, Keratinocytes, Merkel cells, Langerhans cells B. Keratinocytes, Melanocytes, Merkel cells, Langerhans cells C. Keratinocytes, Melanocytes, Langerhans cells, Merkel cells D. Langerhans cells, Keratinocytes, Merkel cells, Melanocytes E. Langerhans Cells, Melanocytes, Merkel cells, Keratinocytes F. Langerhans cells, Merkel cells, Melanocytes, Keratinocytes G. Merkel cells, Langerhans cells, Melanocytes, Keratinocytes H. Merkel cells, Melanocytes, Langerhans cells, Keratinocytes

G. Merkel cells, Langerhans cells, Melanocytes, Keratinocytes Main Explanation In order of increasing relative abundance in the epidermis: Merkel cells (<1%), Langerhans cells (3-5%), Melanocytes (10-15%), Keratinocytes (80%). Merkel cells are associated with the sense of light touch discrimination and can turn malignant, leading to Merkel cell carcinoma. Langerhans cells are dendritic antigen-presenting immune cells in all layers of the epidermis, though ** most prominent in the stratum spinosum. Langerhans Cell Histiocytosis (LCH) is a rare disease involving clonal proliferation of Langerhan's cells, featuring Birbeck granules. Melanocytes provide pigmentation to the skin and can also become malignant.

The "tennis-racket" shaped structure shown in the electron micrograph below is a characteristic marker of cells typically found in the: A. Stratum granulosum B. Stratum corneum C. Stratum spinosum D. Stratum lucidum E. Both C and D

Main Explanation Birbeck granules are specialized organelles (they possess characteristic tennis racket-shaped heads and pentalamellar tails) that are hypothesized to serve an important function in antigen processing. They are found within the Langerhans cells of the epidermis. These cells are typically located in the suprabasilar region of the epidermis and are most often found within the Stratum spinosum (part of the Stratum malpighii or prickle layer).

This usually invisible clinical manifestation results from the migration of embryonic cells. A. Rosacea B. Keloids C. Blaschko's lines D. Scleroderma

Main Explanation Blaschko's lines are skin lines invisible under normal conditions. They become apparent when some diseases of the skin or mucosa manifest themselves according to these patterns. They follow a "V" shape over the back, "S" shaped whorls over the chest, stomach, and sides, and wavy shapes on the head. *** Blaschko's lines are a clinical manifestation of the disease epidermis nevus. A. Rosacea Rosacea is a usually harmless chronic condition characterized by facial redness or erythema. B. Keloids Keloids are benign, non-contagious scars that may be accompanied by sever itchiness or pain. They result from an overgrowth of granulation tissue and are diverse in presentation, ranging from firm, rubbery lesions to shiny, fibrous nodules and pink or flesh-colored to red or dark brown in color. D. Scleroderma Scleroderma is a chronic systemic autoimmune disease that results in fibrosis.

On physical exam, you notice that your patient's blood vessels are very easily visible through her skin, which appears abnormally translucent and thin. This is most likely due to: APurpura BPustule CEpidermal atrophy DDermal atrophy

Main Explanation Epidermal atrophy is characterized by translucent skin, loss of skin markings, variation in pigmentation, and vessels that are readily visualized. Dermal (and subcutaneous) atrophy on the other hand is characterized by depressions in the skin that are covered with normal epithelium. Dermal atrophy is a side effect of prolonged application of topical corticosteroids. Atrophy as well as telangiectasia and striae may appear as soon as 2-3 days after application is started. This is because steroids downregulate # interleukin 1, which is responsible for # cornification in skin cells, while causing suppression of fibroblasts, which help produce new skin cells. The image below shows dermal atrophy from corticosteroid use.

Which of the following cell type(s) is not found in the epidermis? A. Langerhans cells B. Merkel cells C. Fibroblasts D. Melanocytes E. Both C and D

Main Explanation Fibroblasts are cells associated with the dermis, not the epidermis. Recall that fibroblasts are the cells responsible for supplying the dermis with its connective tissue matrix components (collagen, elastic tissue, ground substance). All of the other cell types listed in this question can be found within the epidermis.

A 77-year-old man has multiple, painful blisters located on his face, neck, and torso. The patient complains that he cannot stop scratching them. Which additional finding would suggest a diagnosis of Pemphigus Vulgaris rather than Bullous Pemphigoid? ADenuded skin and flaccid blisters BFever and anorexia CIntact skin and tense blisters DMouth Lesions EPosthealing hyperpigmentation

Main Explanation The correct answer is denuded skin and flaccid blisters. In Pemphigus Vulgaris, the lesions are intraepidermal blisters secondary to IgG autoantibodies against epithelial cell desmogleins 1 and 3. When pressure is applied to these blisters, there is separation of the epidermis (positive Nikolshy's sign), which leads to flaccid blisters and denuded skin. Mouth lesions are always present in pemphigus vulgaris, but they also may be seen in bullous pemphigoid. Tense blisters are found in bullous pemphigoid in which the lesions are subepidermal. However, in pemphigus vulgaris, the lesions are intraepidermal with resulting flaccid blisters. *** In bullous pemphigoid, the eroded skin from ruptured blisters usually reepithelializes well without expansion into the periphery as in pemphigus. New, discrete vesicles may be found at the edges of old, resolving lesions. Posthealing hyperpigmentation may be seen with both diseases although bullous usually ## does not scar. Neither disease usually involves systemic symptoms such as fever and anorexia. Bullae rupture within 1 week, leaving eroded base that does not spread but heals rapidly. Titers do not correlate well with disease activity, unlike in pemphigus.

A 61-year-old woman with leukemia abruptly develops an intensely itchy rash. Physical examination demonstrates multiple erythematous patches of the distal arms and legs, some of which involve the palms and soles. Some of the patches show central clearing with surrounding erythematous rings. Which of the following is the most likely diagnosis? A. Erythema migrans chronicum B. Erythema multiforme C. Kaposi's sarcoma D. Psoriasis E. Urticaria

Main Explanation The most specific clue in the description is the presence of erythematous patches with central clearing, known clinically as "target lesions," which are associated with erythema multiforme. Both erythema multiforme and its severe, life-threatening version, known as Stevens-Johnson syndrome, are produced by ## immune complex deposition in dermal blood vessels. In approximately 50% of patients, no specific precipitating cause is identified. In the remainder of patients, however, a variety of causes have been implicated, including a. Certain infections (herpes simplex, enteroviruses, Mycoplasma pneumoniae, Chlamydia, histoplasmosis) b. Drugs (penicillin, sulfonamides, phenytoin, aspirin, corticosteroids, cimetidine, allopurinol, oral contraceptives) 3. Neoplasia (leukemia, lymphoma, multiple myeloma, internal malignancy) 4. Sarcoidosis, and 5. Foods (notably emulsifiers in margarine). Erythema migrans chronicum (choice A) also produces an annular erythematous rash with central clearing, but usually affects the thigh, groin, and axilla; it is associated with Lyme disease. Kaposi's sarcoma (choice C) causes purple lesions with no target lesions. Psoriasis (choice D) causes erythematous plaques with silvery scale but does not produce target lesions. Urticaria (choice E) causes wheals that are intensely pruritic, but does not produce target lesions.

Anti-inflammatory drugs are the mainstay treatment for pemphigus vulgaris. True False

Main Explanation The pemphigus vulgaris disease process is non-inflammatory. As a result skin lesions do not look inflamed, as they would in bullous pemphigoid, and anti-inflammatory drugs are not effective at treating pemphigus. The current mainstay of pemphigus treatment is aimed at reducing auto-antibody synthesis/binding with such treatments as prednisone (corticosteroid which is a general immunosuppressant), IvIG (increase in circulating IG levels leads to non-specific IG destruction), cyclophosphamide (used in poorer countries), and rituximab (anti-CD20 chimeric monoclonal antibody).

Which of the following mark(s) the boundary between the region of the dermis associated with Type I collagen and the region of the dermis associated with Type III collagen? AFree nerve endings BDeep vascular plexus CMeissner's Corpuscles DPacinian Corpuscles ESuperficial vascular plexus

Main Explanation The superficial vascular plexus marks the boundary between the papillary dermis (associated with Type III collagen) and the reticular dermis (associated with Type I collagen). B. Deep vascular plexus The deep vascular plexus denotes the boundary between the reticular dermis and the subcutaneous fat, not the boundary between the papillary dermis and the reticular dermis. C. Meissner's Corpuscles Meissner's corpuscles are structures associated with the Rete pegs of the dermis (they play a role in the sensation of fine touch), as are free nerve endings (these are associated with the sensation of pain, temperature, and pruritus). D. Pacinian Corpuscles Pacinian corpuscles, although located more deeply (relative to the Meissner's corpuscles), are not associated with the Papillo-reticulo dermal boundary.

A 48 year old female presents to her dermatologist after her hair dresser noticed a "scab" on her scalp that has been present for her last two appointments that bled once after she brushed over it with her comb. Patient is an avid sunbather and tells you she has used self tanning beds twice a month since she was 20 years of age. On exam, there is a raised pearly papule with an area of central ulceration and overlying telangiectatic vessels. Which of the following is most applicable to this lesion? A. It frequently originates as a pre-existing actinic keratosis. B. It is locally aggressive and frequently metastasizes; depth of invasion predicts risk for metastasis C. It is a benign skin condition that requires no further workup. D. It is locally aggressive but almost never metastasizes. E. It is the least common form of malignant skin cancer.

Main Explanation This stem describes the lesion of basal cell carcinoma (BCC), a malignancy that arises from the basal cell layer of the epidermis. Histologically, BCC appears as cords of basophilic staining basal cells infiltrating the underlying dermis. BCC is caused by chronic exposure to ultraviolet light and is thus most often found on the parts of the body that are chronically exposed to sunlight such as the scalp. BCC is locally aggressive and carries a very small risk of metastasis, as compared to malignant melanoma (answer choice B) which is locally aggressive and is associated with frequent metastases. Answer A: describes squamous cell carcinoma (SCC) which is often preceded by lesions of actinic (solar) keratosis. SCC are scaly nodular lesions that are often ulcerated and are often found most commonly in areas of the body commonly exposed to sunlight. ## Like BCC, SCC caries minimal risk for metastasis. Answer C: can describe many skin lesions including a nevocellular nevus (mole) which is a benign tumor of neural crest derived melanocytes (nevus cells). Benign nevi carry no risk of malignancy and do not require further workup. ## Dysplastic nevi, on the other hand, can progress into malignant melanoma, and are often identified by having irregular borders, irregular coloring and/or diameter >6mm. Answer E: is a distraction as BCC is the most, not least, common malignant skin tumor.

A lacrosse player develops athlete's foot (tinea pedis). A drug with which of the following mechanisms would be most effective for this patient? A. Binding to hemagglutinin B. Blockade of mycolic acid incorporation into cell wall C. Inhibition of ergosterol synthesis D. Inhibition of reverse transcriptase E. Inhibition of transcription

Main Explanation Tinea pedis is a fungus and therefore does not have mycolic acids (B), reverse transcriptase (D), or hemagglutinin (A). A transcription inhibitor (E) would also affect the patient's normal cells, resulting in terrible side effects. Therefore, (drugs like Miconazole, Itraconazole, and Clotrimazole inhibit synthesis of ergosterol from lanosterol) inhibition of ergosterol synthesis (C) is the most effective therapy.

After dermatology lecture a classmate of yours decides to bring back the days of elementary school when precocious children used to taunt, "Your epidermis is showing!" He singles you out, unfortunately, and says, "Your verrucae are showing!" What is he referring to? A. Hives B. Moles C. Freckles D. Hair E. Warts

Main Explanation Verrucae are warts, which may be caused by HPV as well as other pathogens. They result from epidermal hyperplasia or hyperkeratosis. You may want to get that checked out, because your classmate may be referring to verruca vulgaris on your hands (hopefully not condyloma acuminatum, which can be massive genital warts!).

Keloids typically respect the boundaries of the initial skin injury. True False

Main Explanation A hypertrophic scar respects the boundaries of the initial injury whereas keloids typically extend beyond the initial boundary. There is an increased risk of keloids in darker pigmented patients (and virtual absence in albinos), suggesting that there may be a role of melanocytes in their formation.

What term describes a skin lesion that is raised, has an irregular shape, and does not contain fluid? AMacule BVesicle CPapule DPurpura

Main Explanation A papule is a lesion that is raised above the skin but contains no fluid. The surface of the lesion can take a variety of textures (from smooth to scaly) and can be in a variety of shapes (irregular, annular, etc).

Which of the following are produced by fibroblasts within the dermis? A. Collagen B. Elastin C. Fibronectin D. Glycosaminoglycans such as chondroitin sulfate (ground substance) E. All of the above are produced by fibroblasts within the dermis

Main Explanation All of the above are produced by fibroblasts of the dermis. Recall that the dermis contains both connective tissue matrix components as well as vasculature, nerves, and epidermal appendages. Each of the substances listed above comprise the connective tissue matrix that is characteristic of the dermis. Fibroblasts are the chief cells of the dermis and are responsible for the production of many molecules comprising the connective tissue matrix, including collagen, elastin, and ground substance (ground substance, or the extracellular matrix, is a catch-all term that includes molecules such as fibronectin, hyaluronic acid, dermatin sulfate, and chondroitin sulfate (glycosaminoglycans)).

A patient presents to your clinic with a clearly evident fungal infection of his toenail. You correctly diagnose him with distal subungual onychomycosis. Which of the following fungi is the most likely cause? A. Malassezia B. Trichophyton rubrum C. Trichophyton interdigitale D. Candida albicans

Main Explanation Also known as dermatophytic onychomycosis or tinea unguium, onychomycosis literally means a fungal infection of the nail. Toenail infections are more common than fingernail infections. There are four distinct patterns. Several patterns may occur simultaneously. • Distal subungual onychomycosis- Most common pattern. Fungi invade distal area of nail bed. Distal plate turns yellow or white as an accumulation of hyperkeratotic debris causes nail to rise and separate from underlying bed. Characterized by T. rubrum invasion of nail bed and underside of nail plate • White superficial onychomycosis- Fungal invasion of superficial layers of the nail plate, forming "white islands" on the plate Caused by surface invasion of nail plate, most often by Trichophyton mentagrophytes. Nail surface is soft, dry, powdery, and can easily be scraped away. ## Nail plate is not thickened. • Proximal subungual onychomycosis-Microorganisms enter the area of posterior nail fold cuticle, invade nail plate from below. Fungal penetration of the nail plate through the proximal nail fold. Surface remains intact. Hyperkeratotic debris causes nail to separate. Most commonly found in immunocompromised patients Trichophyton rubrum is most common cause. • Candidal onychomycosis - Nail plate infection caused by Candida albicans is seen almost exclusively in chronic mucocutaneous candidiasis, a rare disease. Generally involves all the fingernails. Nail plate thickens and turns yellow-brown. often occurring in people who frequently immerse their hands in water,

Apocrine sweat glands exit into the hair shaft above the sebaceous gland. In contrast, eccrine sweat glands exit into the epidermis directly. True False

Main Explanation Apocrine sweat glands are localized to the axillae (armpits), genitoanal region, and areola of the nipples. Specialized apocrine sweat glands on the eyelids are called Moll's glands. The majority of the body is covered by eccrine glands, which are shown in the image below and labeled "sudoriferous gland," meaning sweat gland.

Asteatotic dermatitis may result from frequently taking hot, soapy showers or baths and living in rooms with high temperatures and low relative humidity. True False

Main Explanation Asteatotic dermatitis, also known as xerotic eczema and eczema craquelae, causes "cracked", fissured skin with slight scaling and typically occurs in the elderly during the winter. Any site may be affected, although lower legs most commonly involved. • Early, affected individuals often note that skin looks and feels dry. • With progression, itch and increasing inflammation become most prominent symptoms. • Burning, stinging occur in advanced cases with fissures, crusting Treatments include moisturizers, especially those that contain urea and lactic acid, and topical steroids for areas that get very itchy and inflamed.

A 62-year-old female journalist is brought to the emergency room after fainting at a fancy dinner at the British embassy. Upon admission her vitals are T: 102.1, HR: 97, BP: 120/85, RR: 12. She states that she began to feel dizzy and sat down in a chair, but does not believe she lost consciousness. In the afternoon prior to the dinner, she states that she had been feeling fatigued and chilled and noted some itching on her stomach, but did not think she was ill enough to miss such an important event. The image below shows what you see on physical exam of her abdomen. Which of the following microscopic findings is associated with these disease? A. Multinucleated giant cells B. Koplik spots C. Negri bodies D. Foamy macrophages E.None of the above

Main Explanation Barbara Walters fainted at a British embassy dinner and was found to have chicken pox (varicella zoster virus infection). It is unusual (but not unheard of) for adults to get primary chicken pox. However, unlike children, their disease is often more serious. Although many adults with VZV infection will have uncomplicated course, they are typically hospitalized and do have an increased risk of developing pneumonia when compared to children. The image in the question stem shows an early fluid-filled blister typical of the early stages of chicken pox. The classic finding of VZV infection is multinucleated giant cells on a tzanck smear. You can also see multinucleated giant cells in herpes simplex, herpes zoster, CMV and pemphigus vulgaris.

A 64-year old male patient presents to your dermatology clinic with a pearly and translucent lesion on his nose. An overlying telangiectasia is also visible. Which type of skin cancer does this patient most probably have? A. Basal cell carcinoma B. Squamous cell carcinoma C. Low-risk melanoma D. High-risk melanoma

Main Explanation Basal cell carcinomas are usually pearly and translucent with overlying telangiectasias. They can ulcerate and bleed. Superficial basal cell carcinoma can appear as a red patch, like eczema.

A 62-year-old male actor comes to the physician three days after he noticed a lesion on his nose. He was on set and when he scratched his nose, he thought he had removed a scab because it was bleeding. However, his makeup artist was concerned and suggested he go to the doctor. In addition to being an actor, the man is an avid mountain climber and loves spending hours climbing in the sun. Examination of his nose reveals a 2-mm pearly pink raised nodule. Which of the following diagnoses is most likely? A. Actinic keratosis B. Squamous cell carcinoma C. Eczema D. Basal cell carcinoma E. None of the above

Main Explanation Both the appearance of the lesion (pink, pearly raised nodule) as well as the fact that he gets a lot of sun exposure (mountain climbing) both support the diagnosis of BCC. Because BCC can invade surrounding tissues, it needs to be treated. Common options are surgical excision, Mohs surgery (in which the specimen is immediately examined and margins can be assessed on the spot), and superficial chemotherapy (a gel or cream like 5-FU).

A 68-year old Caucasian female presents to the hospital with large red plaques covering her body. Dramatic blisters are also apparent. These lesions are pruritic, but are not painful. What disease is at the top of your differential? AEpidermolysis bullosa BPemphigus vulgaris CEhlers-Danlos syndrome DBullous pemphigoid EPemphigus foliaceus

Main Explanation Bullous pemphigoid is a disease of the elderly, normally peaking around 60 - 80 years of age. It is characterized by large, pruritic (itchy) and painless plaques covered with large blisters (a secondary manifestation). ## It is also much more common than pemphigus vulgaris.

Former Soviet President Mikhail Gorbachev came to your practice for a routine check-up. You noticed the mark on his scalp and when you asked him about it he said, in a thick Russian accent, that it used to be pink when he was younger. What type of vascular malformation does he have? A. Capillary malformation B. Venous malformation C. Lymphatic malformation D. Klippel Trenaunay E. Arteriovenous malformation

Main Explanation Capillary malformations (CMs) result in a typical "port wine stain." Facial CMs may lead to Sturge Weber syndrome, which is a sporadic neurocutaneous disorder that results in seizures, glaucoma, and other neurological issues. ## The "stain" typically changes color from pink/red to crimson or dark purple. Treatment includes pulsed dye laser to lighten, but maintenance is often required. A. Capillary malformation Capillary malformations result in a typical "port wine stain." Facial CMs may lead to Sturge Weber syndrome, which is a sporadic neurocutaneous disorder that results in seizures, glaucoma, and other neurological issues. The "stain" typically changes color from pink/red to crimson or dark purple. Treatment includes pulsed dye laser to lighten, but maintenance is often required. B. Venous malformation Venous malformations are the most common type of vascular malformation. They typically appear blue-purple and are soft and compressible. Therapy includes compression garments, sclerotherapy, surgical excision, and laser. C. Lymphatic malformation Lymphatic malformations can be superficial (microcystic) or visceral (macrocystic), the latter being huge cysts filled with lymph that may obstruct the airway and cause the head to be pear-shaped. D. Klippel Trenaunay KT is either a capillary venous malformation (CVM) or capillary lymphatic venous malformation (CLVM). It results in progressive overgrowth of the affected limb (usually lower) and can lead to localized intravascular coagulation. E. Arteriovenous malformation ## These are the most dangerous types of vascular malformations and often flare at puberty, pregnancy, or after trauma. About 40 percent are congenital and visible at birth.

After dermatology lecture a classmate of yours decides to bring back the days of elementary school when precocious children used to taunt, "Your epidermis is showing!" He singles you out, unfortunately, and says, "Your ephelis are showing!" What is he referring to? A. Wart B. Hair C. Hive D. Mole E. Freckle

Main Explanation Ephelis is the term for freckle. There are a normal number of melanocytes in freckles, just increased amount of melanin.

Acne is the result of a follicular occlusion syndrome associated with the eccrine glands. True False

Main Explanation False - Acne is the result of a follicular occlusion syndrome associated with sebaceous glands. Recall that sebaceous glands are associated with hair shafts, as are the arrector pili muscles. Sebaceous glands can be found everywhere (e.g. face, chest, scalp, back) except the palms and soles, and become functionally active at puberty. The sebaceous glands are responsible for secreting sebum, an emollient for the skin and hair. The eccrine glands, in contrast, are found everywhere except the mucous membranes and are particularly dense on the palms, soles, axillae, and forehead. Unlike the sebaceous glands and apocrine glands, the eccrine sweat glands are NOT associated with hair follicles—instead, their ducts empty directly into the epidermis. The follicular occlusion syndrome associated with eccrine glands is known as Miliaria ("Sweat rash" or "prickly heat"), a condition that is characterized by punctate, pruritic red spots.

A young boy puts a ring on his finger and soon forgets it is there. Which sensory receptor was the first to stop responding to the stimulus? A. Free Nerve Ending - C fibers B. Free Nerve Ending - A Delta fiber C. Meissner's Corpuscle D. Pacinian Corpuscle E. Merkel's Disks

Main Explanation Free nerve endings - Pain and temperature sensation. Meissner's Corpuscle - Position sense, fine touch. Because this receptor is rapidly adapting, it is the correct answer. Pacinian Corpuscle - Vibration, pressure. Merkel's Disk - Position sense, static touch, and slowly adapting.

An 18-year old high school wrestler presents with a skin infection that has a characteristic golden crust, as seen in the picture below. What is the most likely infection? A. Cellulitis B. Impetigo C. Intertrigo D. Necrotizing fasciitis

Main Explanation Impetigo is a common skin infection, characterized by a golden crust, that is caused by streptococcus or staphylococcus bacteria. When there is a break in the skin, bacteria can enter the body and grow there, resulting in subsequent infection and inflammation. The symptoms of Impetigo include: - A single or possibly many blisters filled with pus - Itching blister(s) filled with yellow or honey-colored fluid that is oozing and crusting over - Rash that may begin as a single spot, but may spread to other areas due to scratching - skin lesions on the face, lips, arms, or legs, that spread to other areas - lymphadenopathy.

Infantile hemangiomas are the most common type of vascular malformation. True False

Main Explanation Infantile hemangiomas are by far the most common type of vascular tumor. Venous malformations are the most common type of vascular malformation. The distinction between vascular tumors and vascular malformations is critical to appropriately diagnosing and treating various vascular anomalies. Vascular tumors can vary significantly in size and severity, but are usually ## not painful, unless ulcerated. Infantile hemangiomas can also be superficial and very red, or deep and appear bluish. Deep hemangiomas tend to grow much longer than superficial hemangiomas, which double in size during the first two months of life.

What common fungal infection, seen in the image below, is localized to the skin folds of the axilla and genitalia and is often found on morbidly obese individuals? A. Perleche B. Impetigo C. Intertrigo D. Cellulitis

Main Explanation Intertrigo is an inflammation (rash) of the body folds. It can be caused by a bacterial, fungal, or viral infection; a frequent manifestation is Candidal intertrigo caused by Candida albicans.

The difference between a hypertrophic scar and a keloid is that a keloid stays within the boundaries of the original lesion. True False

Main Explanation It is the opposite. A keloid (more common in dark-skinned people) does not respect the boundaries of the original lesion. Contrastingly, a hypertrophic scar does not grow beyond the boundaries of the original wound.

A 12-year-old blind boy is learning to read Braille for the first time. Unlike the sensory organ involved in recognizing the presence of a character, which sensory organ in his finger tips is responsible for recognizing the spatial characteristics (e.g., angles, points, curves) into electrical signals? A. Hair follicle B. Meissner's Corpuscle CMerckel's Corpuscle DPacinian Corpuscle EVestibular apparatus

Main Explanation Meissner's corpuscle recognizes light, discriminatory touch in hairless skin and are thus responsible for translating specific characters into electrical signals. Merckel's corpuscle forms discs that convey light, crude tactile sensation (which can sometimes be conveyed through hair follicles) and thus help in the temporal recognition. The Pacinian corpuscle enables pressure, vibration, and tension sensation. The vestibular apparatus is located in the ear and enables perception of acceleration.

In pemphigus vulgaris, auto-antibodies are made against a component of which of the following? AKeratin BDesmosomes CFibrin DCollagen EHemidesmosomes

Main Explanation Pemphigus vulgaris is an autoimmune disorder that usually occurs in middle-aged or older people. Blisters in pemphigus are fragile, which is why many of the ones in the image provided have broken, or denuded. In pemphigus vulgaris, auto-antibodies are made against a component of desmosomes (i.e. Dsg3) leading to intraepidermal separation.

An 18-year-old male shows up at your clinic with small pustules around hair follicles on the lower portion of his face. What organism is the most likely culprit? A. Pseudomonas aeruginosa B. Streptococcus pyogenes C. Staphylococcus aureus D. Pityrosporum ovale

Main Explanation Staphylococcus aureus is the most common cause of folliculitis.

The layers of the epidermis from most superficial to most deep are: A. lucidum -> granulosum -> corneum -> spinosum -> basale B. lucidum -> corneum -> granulosum -> spinosum -> basale C. corneum -> lucidum -> granulosum -> spinosum -> basale D. granulosum -> corneum -> lucidum -> spinosum -> basale E. corneum -> granulosum -> lucidum -> spinosum -> basale

Main Explanation The epidermis is composed of 4 or 5 layers depending upon the region of the body (the fifth layer, the stratum lucidum, is only on the palms and soles.) From most superficial to most deep they are: Stratum corneum - cornified layer composed of 10-30 rows of polyhedral, anucleated corneocytes that are the final step in keratinocyte differentiation. Stratum lucidum - clear, translucent layer only on the palms and soles. Stratum granulosum - granular layer composed of keratinocytes that lose their nuclei and have granular cytoplasm. Stratum spinosum - spinous layer consisting of keratinocytes that are connected via desmosomes and begin producing lamellar bodies. This layer also contains ## Langerhans cells which are immunologically active. Stratum basale - basal/germinal layer composed of dividing and non-proliferating keratinocytes attached to the basement membrane. ## Melanocytes are also present in this layer. A mnemonic for these layers is "Cher Likes Getting Skin Botoxed" for corneum, lucidum, granulosum, spinosum, and basale.

Which of the following molecule(s) is associated with the yellow highlighted region in the image below? AType I collagen BType III collagen CType IV collagen DType VII collagen EBoth C and D

Main Explanation The highlighted region indicates the papillary dermis, a region of the dermis that is associated with Type III collagen. The papillary dermis is composed of loose areolar connective tissue and is named for its fingerlike projections that extend into the epidermis. It contains either terminal networks of blood capillaries or tactile Meissner's corpuscles. The reticular dermis is associated with Type I collagen, and the basement membrane is associated with both Type IV and Type VII collagen. This gives the dermis its strength and extensibility. The reticular region includes sebaceous glands, sweat glands, hair roots, and blood vessels. A mnemonic is that the word "papillary" (dermis) looks like it contains Roman Numeral III -- thus, the Papillary dermis is associated with Type III collagen.

"Free floating keratinocytes" (circled in red) seen in an H&E stain of the skin is a hallmark of what disease? A. Folliculitis B. Shingles C. Impetigo D. Pemphigus Vulgaris

Main Explanation The image above shows clear separation of the dermis from the epidermis, and "free floating keratinocytes" that have been released from the torn epidermal tissue. This is the hallmark of pemphigus vulgaris.

A 32 year old Caucasian woman, a well-known television personality, presents to your office with an "itchy rash." She has had it off and on for years, but it has been particularly bad in the last 6 months. She explains the rash usually occurs on her forearms and elbows, but she has also had it on her back and buttocks. She tries to not scratch, but "can't help sometimes because it's so itchy." She has tried lotions and moisturizers with no improvement. She had a thyroidectomy in her twenties due Graves' Disease and currently takes thyroxine. On review of systems, she endorses occasional headaches, anxiety about her job, as well as frequent nausea and loose stools after meals. On exam, she is a thin woman in no acute distress. Cardiovascular and pulmonary exams are unremarkable. She has multiple, grouped vesicles and papules distributed over her dorsal forearms, elbows, back and buttocks. Multiple excoriations are noted. A representative picture is shown below. Your abdominal exam reveals normo-active bowel sounds and a soft, non-tender abdomen. What test would you order to confirm the diagnosis? A. Punch biopsy B. Un-roof vesicle and send for viral analysis C. Anti-gliadin antibodies IgA and IgM D. Patch testing with multiple fabric types

Main Explanation The patient presents with a rash that is herpetic in appearance, but it appears in multiple locations not usually associated with herpes simplex. This is likely Dermatitis Herpetiformis, a skin condition most often associated with Celiac Disease. Additionally, she is Caucasian, has history of autoimmune disorders (Graves') and persistent GI symptoms. In this context, you should suspect Celiac Disease. The initially screening test would be serum levels of anti-gliadin antibodies. A. Punch biopsy: Punch biopsies are often used in dermatologic diagnoses. However, the overall clinical picture of this patient is suspicious of Celiac Disease. A punch biopsy of Dermatitis Herpetiformis lesions may show IgA deposition in the dermal papillae under Direct Immunofluorescence microscopy, but would be non-specific in this clinical picture. B. Un-roof vesicle and send for viral analysis: While herpes is often diagnosed clinically, vesicular fluid can be sent for viral analysis to confirm the diagnosis. A primary herpes infection or reactivation should certainly be on the differential, but the patient's constellation of symptoms point towards celiac. C. Anti-gliadin antibodies IgA and IgM: Anti-gliadin antibody testing is the first step in the Celiac Workup. Patients with positive serum antibodies will require a small bowel biopsy for confirmation of disease. D. Patch testing with multiple fabric types Patch testing is often used for suspicion of acute contact dermatitis. The patient's history describes a chronic course and contact dermatitis could not explain the GI symptoms.

A 38-year-old Asian female presents to your office with the lesion shown in the picture below. She states that she recently had several sores in her mouth that were so painful she could barely eat. Upon careful examination of the lesion, you notice that the outer region is very wrinkled, and there are no signs of inflammation. The patient also states that the crust occurred after the lesion was present for several days. What is the most likely diagnosis? A. Bullous pemphigoid B. Psoriasis C. Pemphigus vulgaris D. Varicella zoster virus

Main Explanation The scenario above describes a classic case of pemphigus vulgaris. Asians are sometimes found to have a mutation in their DQ1 gene, which is correlated to the presence of the disease. The peak incidence of pemphigus vulgaris (PV) is at ~50 years of age, but there is a broad range of affected ages. PV, which is non-inflammatory, usually begins with painful oral lesions followed by skin lesions appear. Wrinkling of the outer region of the legion is due to the separation of the epidermis from the dermis. Histologically this is characterized by "tombstoning" of the epidermis from the dermis as shown in the image below.

The structure(s) indicated by the arrow are associated with which of the following? A. Fine touch B. Slow adapting touch C. Deep pressure D. Vibration E. Temperature, pain, & pruritis F. Deep pressure and vibration G. Fine touch, temperature, pain, and pruritis

Main Explanation The structures designated in the figure are the Pacinian corpuscles. The Pacinian corpuscles are structures that exhibit an ## onion-like histological appearance and are associated with the ## nerve supply in the dermis. These structures are associated with both ## deep pressure and vibration. The top-most structures, from left to right, are the: a. Merkel cells: cells associated with ## slow adapting touch that are attached to myelinated nerves and are found in both the epidermis and dermis, Free nerve endings: associated with temperature, pain, and pruritis, Meissner's corpuscles: cells associated with fine touch and found within the Rete pegs of the dermis.

Eccrine sweat glands are found only in the axillae, groin, eyelids, and external auditory canal. True False

Main Explanation This is the description of apocrine sweat glands. Eccrine sweat glands are found everywhere except mucous membranes. You can remember this with the mnemonic, "Eccrine are found (almost) Everywhere!"

A 32 year old otherwise healthy man presents to your office with pain in his right second toe. He is a musician and an avid soccer player and believes he may have injured it during a recent match, though he cannot recall details. He denies recent fevers, sweats, chills, or weight loss. On exam, he is a well-appearing young male in no acute distress. He has full strength, sensation and reflexes in lower extremities bilaterally. The right second toe is tender to palpation and a subungual discoloration is present, extending into the proximal nail fold. A picture similar to the patient's condition is seen below. Which of the following risk factor for this patient's condition? A. Family history of clotting disorder B. Dark-skin C. Diabetes D. History of podiatric surgery

Main Explanation This patient case is based on the reggae artist Bob Marley. His presentation of toe pain, initially thought to be a soccer injury, was later discovered to be Acral Lentiginous Melanoma (ALM), which only comprises 5% of all melanomas. ##However, ALM is the most common type of melanoma among dark-skinned and Asian populations. ## ALM commonly affects the soles of the feet or appears as a subungual discoloration in the form of a # dark band. @@ Involvement of the proximal nail fold is suspicious for ALM and is referred to as Hutchinson's sign. Bob Marley refused amputation of the toe on religious grounds. In 1981, he passed away from complications of metastatic melanoma

A 31 year old chef with no prior past medical history presented to his dentist with a painful "white dot" on the lateral surface of his tongue. Ha had no history of oral ulcers. He had never smoked, does not drink, and has no known family history of cancer. The white lesion is not scrapable. A biopsy is taken and returned with the following description: "keratin pearls with intracellular bridging." Which diagnosis is most likely? A. Canker sore (aphthous stomatitis) B. Behcet's Syndrome C. Thrush (oral candidiasis) D. Oral squamous cell carcinoma

Main Explanation This patient is Alinea chef Grant Achatz from Chicago. In early 2007 he was diagnosed with Stage IVb squamous cell carcinoma of the tongue. Chef Achatz declined the standard treatment at the time (glossectomy and reconstruction) because he would lose his sense of taste. He opted for chemo + radiation without surgery, saving his tongue, taste, and career. In late 2007 he showed no evidence of disease and continues to operate his world-renowned restaurant.

A 23-year-old man presents to your office with a five day history of unremitting fever and right wrist pain. He denies a history of illicit drug use. Vitals are as follows: HR 118, BP 135/90, RR 20, T 101.9F. The patient is noticeably anxious. On physical exam, his right wrist and left elbow are both painful to palpation. No needle marks are visible. Small papular, non-pruritic lesions are noted on his back. Which of the following is the likely event that introduced the pathogen for this patient's presentation? A. Airborne droplets B. Fecal-oral transmission C. Needle stick injury D. Operative injury E. Unprotected sexual contact

Main Explanation This patient is presenting with likely gonococcal arthritis given his young age, polyarticular symptoms, fever and rash. It is likewise probable that he was infected during unprotected sexual contact with an individual exhibiting genital gonorrhea. Our patient was unable to contain the organism locally, either due to a failure in his own immunity or the increased virulence of the gonococcal strain, and he presented with the arthritic form. Airborne droplets can create an osteomyelitis-type picture in the case of TB-induced Pott's disease of the vertebrae, particularly in indigent populations in developing countries. However our patient fits none of the risk factors or symptoms for TB. Fecal-oral transmission may create osteomyelitis in the case of Salmonella, but this is particular in patients who are already afflicted with sickle cell disease. Needle sticks and operative injury may introduce myriad organisms that can cause septic arthritis (i.e. Staph aureus, Pseudomonas aeruginosa), but our patient has no history of this type of introduction.

A 37-year-old man has multiple blisters located in his mouth. He complains that they are painful, burst easily and make it difficult to eat. A biopsy of one of the blisters was stained and shown. Immunofluorescent antibodies directed against which protein would produce a similar pattern to the biopsy? A. Cadherin B. Fibronectin C. Integrin D. Keratin E. Laminin

Main Explanation This patient is suffering from Pemphigus Vulgaris, as demonstrated by the clinical presentation (multiple, flaccid, painful blisters) and Immunofluorescence biopsy. Note the intercellular IgG deposits in the epidermis and the early intraepidermal vesicle caused by acantholysis. In Pemphigus Vulgaris, autoantibodies are directed against the desmosomes which attach neighboring cells to each other. The question asks you to take this information one step further, and recall from your Cell Biology course that Desmosomes (macula adherens) are members of the Cadherin (Choice A) family of cell adhesion molecules. Fibronectin (Choice B) is a ECM glycoprotein that binds to integrins, collagen, fibrin and heparan sulfate. It would produce a different staining pattern and is not involved in Pemphigus. Integrins (Choice C) are receptors that mediate attachment between a cell and the tissues or ECM surrounding it. They also play a role in cell signaling and thereby define cellular shape, mobility, and regulate the cell cycle. They are not involved in Pemphigus and would produce a different staining pattern. Mutations in the gene for Keratin (Choice D) lead to Epidermolysis bullosa, a disorder characterized by recurrent blisters. Autoantibodies are not involved in the pathogenesis of this disorder, and immunofluorescence staining to keratin would produce a different pattern. Laminin (Choice E) is a protein found in the extracellular matrix that forms the basement membrane. It is not involved in Pemphigus and would produce a different staining pattern.

A 25-year-old male presents complaining of several weeks of itching lesions on his legs and arms. On exam, there are sharply demarcated erythematous plaques with silvery scale on the lower legs and extensor surfaces of the arms bilaterally. Which of the following drugs would be most likely to alleviate the patient's symptoms? A. Amoxicillin, oral B. Betamethasone, topical C. Fluconazole, oral D. Ketoconazole, topical E. Mupirocin, topical

Main Explanation This patient most likely has plaque psoriasis, an immune-mediated disease caused by hyperproliferation of keratinocytes in the epidermis and inflammatory cell infiltrates. While the details of psoriasis pathogenesis and treatment are complex, the mainstay of treatment for psoriasis are anti-inflammatory and immunomodulatory therapies (e.g.: topical steroids, topical calcineurin inhibitors, and anti-TNF-alpha agents). Of the answer choices, the only drug which falls under these categories is betamethasone (B), a moderately potent corticosteroid that can be administered topically. Other answer choices (listed below) would not be effective in treating an immune-mediated condition such as psoriasis. Amoxicillin (A) is an beta-lactam aminopenicillin antibiotic that is most effective against Gram-positive bacteria that do not produce beta-lactamase. Fluconazole (C) is a triazole antifungal that inhibits cytochrome p450 and sterol C-14 alpha-demethylation. It is useful in treating a number of fungal infections, including candidiasis, cryptococcal meningitis, and tinea infections. Ketoconazole (D) is an antifungal that inhibits fungal cell membrane ergosterol synthesis. Mupirocin (E) is a topical antibiotic that selectively binds to bacterial isoleucyl transfer-RNA synthetase, inhibiting protein synthesis. It is used to treat bacterial skin infections.

A 27 year-old man presents with numerous erosions of his mucous membranes. Examination of his oral cavity reveals painful oral ulcers and a friable mucosa Immunoflourescence evaluation demonstrates intraepidermal band of IgG. A biopsy of the lesion shows breakdown of intercellular epithelial connections. Which of the following is the most likely diagnosis in this patient? A. Herpetic ulcers B. Measles C. Dermatitis herpetiformis D. Pemphigus vulgaris E. Bullous pemphigoid

Main Explanation This question requires that you differentiate between intraepidermal IgG as in pemphigus vulgaris and deeper layers of the skin involving the dermal-epidermal junction as in Bullous pemphigoid. The latter produces tense blisters that do not usually ulcerate. Furthermore, oral involvement typically occurs in pemphigus vulgaris. A. Herpetic ulcers There is no intraepidermal IgG deposition in herpetic ulcers. B. Measles There is no intraepidermal IgG deposition in Measles. C. Dermatitis herpetiformis Dermatitis herpetiformis is an extraintestinal manifestation of celiac's disease. This rash is characterized by IgA and C3 deposition, not IgG. E. Bullous pemphigoid Bullous pemphigoid produces tense blisters that do not usually ulcerate and oral involvement typically occurs in pemphigus vulgaris.

A boy scout returns home after a three-day adventure in the woods with a pruritic, linear, vesicular eruption. His mother brings him to the dermatologist and he is diagnosed with poison ivy dermatitis. What type of reaction is this? AType I BType II CType III DType IV EType V

Main Explanation Type IV hypersensitivity reactions are T-cell mediated reactions, which are responsible for the contact dermatitis seen in poison ivy. Type I reactions are anaphylactic (e.g. seasonal allergies). Type II reactions are antibody-antigen mediated (e.g. Goodpasture's nephritis). Type III reactions are immune complex mediated (e.g. rheumatoid arthritis). ** Type V reactions are antibody-stimulating (a subtype of Type II) (e.g. Graves disease).

Albinism may result from mutations in the gene encoding this rate-limiting enzyme of the melanin biosynthetic pathway. A. Tyrosine kinase B. Tyrosinase C. Melaninase D. Melanosomase

Main Explanation Tyrosinase catalyzes the production of melanin and other pigments from tyrosine by oxidation. Mutations in the tyrosinase gene can lead to albinism.

Which of the following vascular malformations is most common? ACapillary malformation BVenous malformation CLymphatic malformation DKlippel Trenaunay EArteriovenous malformation

Main Explanation Venous malformations are the most common type of vascular malformation. They typically appear blue-purple and are soft and compressible. Therapy includes compression garments, sclerotherapy, surgical excision, and laser. A. Capillary malformation Capillary malformations result in a typical "port wine stain." Facial CMs may lead to Sturge Weber syndrome, which is a sporadic neurocutaneous disorder that results in seizures, glaucoma, and other neurological issues. The "stain" typically changes color from pink/red to crimson or dark purple. Treatment includes pulsed dye laser to lighten, but maintenance is often required. B. Venous malformation Venous malformations are the most common type of vascular malformation. They typically appear blue-purple and are soft and compressible. Therapy includes compression garments, sclerotherapy, surgical excision, and laser. C. Lymphatic malformation Lymphatic malformations can be superficial (microcystic) or visceral (macrocystic), the latter being huge cysts filled with lymph that may obstruct the airway and cause the head to be pear-shaped. D. Klippel Trenaunay KT is either a capillary venous malformation (CVM) or capillary lymphatic venous malformation (CLVM). It results in progressive overgrowth of the affected limb (usually lower) and can lead to localized intravascular coagulation. E. Arteriovenous malformation These are the most dangerous types of vascular malformations and often flare at puberty, pregnancy, or after trauma. About 40 percent are congenital and visible at birth.

Blisters are elevated lesions that contain clear fluid. They are a type of: APurpura BPustule CMacule DVesicle

Main Explanation Vesicles are raised lesions that contain clear fluid. If the vesicle is larger than 1 cm in diameter, it is called a bulla.

A mother shows up to the emergency room with her 2-year-old daughter stating her child has been crying a lot when she has a bowel movement. The child's stool is blood-streaked and, upon examination, you find she has perianal erythema. Which of the following characterizes the organism causing this skin infection? A. Catalase positive B.Beta hemolytic C. Alpha hemolytic D. Spaghetti and meatball KOH prep

This child has perianal cellulitis, which is also known as perineal dermatitis and streptococcal perianal disease. The characteristic organism is Group A streptococcus (GAS), which is beta hemolytic and also causative of acute rheumatic fever and poststreptococcal glomerulonephritis. Perianal cellulitis is generally treated with oral antibiotics, most commonly penicillin, for 1-2 weeks. Mupirocin may also be applied topically, but only in addition to other antibiotics.

Vitiligo is an autoimmune disease that causes T-cell mediated destruction of the melanocytes and is more common in dark-skinned individuals. True False

True Main Explanation Vitiligo is currently treated with topical (steroid) therapy to suppress the T-cell response or photo therapy to stimulate pigmentation. It has also been treated by removing pigmentation of native areas, skin grafting, and tattooing.

A 24 year old male presents with well-defined patches of skin depigmentation on the hands and arms bilaterally. He also complains of pruritis over these areas and is very uncomfortable with his appearance. You diagnose him with vitiligo. Which of the following are potential treatments that may help this patient? A. Topical hydrocortisone B. Supplemental vitamin B3 C. Methotrexate D. Melatonin supplementation

Vitiligo is a poorly understood condition in which melanocytes either die or lose the ability to produce melanin. The primary theory is that this is an autoimmune condition. Topical corticosteroids have anti-inflammatory properties that may ease symptoms of pruritis and have had beneficial effects in some patients. B. Supplemental vitamin B3 Vitamin D may play a role in skin cell development, not vitamin B D. Melatonin supplementation Melatonin is a hormone thought to play a role in sleep regulation. Melatonin is not to be confused with melanin.