Derma Channel (OSCE slides, lectures, MCQs and discussion)

A 73-year-old White man presents for evaluation of gradually progressive facial skin changes. He reports that over the past several years, he has noticed an increasing number of “blackheads” and small bumps around his eyes and upper cheeks. The lesions do not cause pain, pruritus, or drainage. His past medical history is notable for hypertension, and he reports a 40-pack-year smoking history. He worked as a farmer for over 40 years and rarely used sun protection. Physical examination reveals numerous open comedones and cystic papules clustered symmetrically over the periorbital and zygomatic regions bilaterally. The surrounding skin appears thickened, yellowish in hue, and with prominent wrinkling. The lesions are non-tender and without surrounding erythema or inflammation. No similar findings are noted on the chest or back. The remainder of the skin examination is unremarkable. What is the most likely diagnosis? A-Milia B- Acne C- Favre-Racouchot D- Colloid milia

A 35-year-old man presents to the dermatology clinic for evaluation of a skin lesion on his right calf. He reports noticing the bright red spot approximately 8 months ago and has remained the same size. He also noted a few similar spots on his trunk. All of the lesions are entirely asymptomatic and have never bled. His medical history is unremarkable, and he takes no daily medications. On physical examination, the skin of the right calf reveals a well-demarcated, dome-shaped, bright red-colored papule. Examination of the trunk reveals a few similar 1 mm to 5 mm vascular proliferations. What is the most likely diagnosis? A- Lobular capillary B- hemangioma C- Pyogenic granuloma Cherry angioma Glomeruloid hemangioma

24-year-old woman presents for evaluation of a persistent, itchy rash on her right arm. She reports that over the past several months, she has noticed a dry, irritated patch in the crease of her right elbow. The lesion is associated with intense pruritus, which frequently leads to repeated scratching. She notes that the redness and itching are significantly exacerbated after taking long, hot showers. She denies any spontaneous hives, spreading of the rash, pain, or systemic symptoms. Her medical history is notable for childhood asthma and seasonal allergic rhinitis, but she is not currently taking any daily medications. Clinical evaluation of the right antecubital fossa reveals a poorly defined erythematous plaque with lichenification and scaling. Excoriations are present within the plaque, corresponding to the patient’s reported pruritus. No vesicles, weeping, or purpura are noted. The remainder of the skin examination is notable for generalized mild xerosis but otherwise unremarkable. What is the most likely diagnosis? A- Allergic contact dermatitis B- Atopic dermatitis C- Psoriasis vulgaris D- Tinea corporis

24-year-old woman presents for evaluation of a persistent, itchy rash on her right arm. She reports that over the past several months, she has noticed a dry, irritated patch in the crease of her right elbow. The lesion is associated with intense pruritus, which frequently leads to repeated scratching. She notes that the redness and itching are significantly exacerbated after taking long, hot showers. She denies any spontaneous hives, spreading of the rash, pain, or systemic symptoms. Her medical history is notable for childhood asthma and seasonal allergic rhinitis, but she is not currently taking any daily medications. Clinical evaluation of the right antecubital fossa reveals a poorly defined erythematous plaque with lichenification and scaling. Excoriations are present within the plaque, corresponding to the patient’s reported pruritus. No vesicles, weeping, or purpura are noted. The remainder of the skin examination is notable for generalized mild xerosis but otherwise unremarkable. What is the most likely diagnosis? A- Allergic contact dermatitis B- Atopic dermatitis C- Psoriasis vulgaris D- Tinea corporis

45-year-old man presents to the dermatology clinic for evaluation of a non-healing skin lesion on his chin. He reports that the spot has been slowly growing over the past 3 years and occasionally bleeds. It used to be a small bump that would only bleed after he shaved, but now it bleeds on its own. He has a history of significant cumulative sun exposure, specifically noting intense, blistering sunburns during his childhood and adolescence. On physical examination, there is a solitary, 4 cm exophytic pink papule with prominent telangiectasias located on the chin. A skin biopsy is performed, demonstrating a proliferation of mutated basaloid cells extending from the epidermis and invading into the local dermal tissue. What is the most likely diagnosis? A- Basal cell carcinoma B- Squamous cell carcinoma C- Melanoma D- Wart

57-year-old man presents to the dermatology clinic for evaluation of skin changes on his upper and lower extremities. He reports that over the past several weeks, he has noticed hyperpigmented, crusted, papular lesions associated with significant pruritus, leading to frequent scratching. His medical history is significant for end-stage renal disease (ESRD), for which he is receiving hemodialysis; heart failure; hypertension, coronary artery disease; and type 2 diabetes mellitus. On examination, the skin of the upper and lower extremities reveals scattered hyperpigmented, crusted papules and nodules. Closer inspection of the lesions reveals distinct central keratotic plugs. Excoriations are present in the affected areas. No vesicles, scale, or purpura are noted. The remainder of the skin examination is unremarkable. What is the most likely diagnosis? A- Pemphigoid B- Prurigo nodularis C- Dermatofibromas D- Acquired perforating dermatosis

24-year-old woman presents for evaluation of transient skin changes on her right thigh. She reports that over the past several months, she has noticed raised, linear marks appearing shortly after scratching or rubbing the area, particularly after shaving or wearing tight clothing.  The lesions are associated with pruritus and typically resolve spontaneously within 30 to 60 minutes, leaving no residual discoloration. She denies spontaneous hives, angioedema, pain, or systemic symptoms. Her medical history is unremarkable, and she is not taking any medications. On examination, the skin of the right thigh appears normal at rest. After gentle scratching of the skin with a blunt object, linear erythematous wheals develop along the areas of contact within several minutes, corresponding to the patient’s symptoms (Figure). No vesicles, scale, or purpura are noted. What is the most likely diagnosis? A- Dermatographism B- Telangiectasia C- Contact dermatitis D- Chronic urticaria

A68-year-old man is referred for evaluation of a scalp lesion that was first noted several weeks ago and has been gradually enlarging in size. The lesion bleeds when traumatized by combing. He has fair skin and admits to ample past sun exposure. A year ago, several actinic keratoses on his hands were treated cryosurgically. Examination reveals a 1.8 cm firm, slightly erythematous nodule. Cervical lymph nodes are nonpalpable. What is the likely diagnosis? A-Nodular basal cell carcinoma B-Atypical fibroxanthoma C-Amelanotic melanoma D-Schwannoma

A 42-year-old woman presented to the emergency department with anaphylaxis shortly after participating in a polar plunge challenge earlier that day. She mentioned that she had experienced several episodes of recurring, unexplained hives on her skin shortly after cold exposures for the past year. The patient’s medical history was uneventful. A cold stimulation test revealed a markedly edematous plaque with surrounding erythema after application of an ice cube. What's the diagnosis? A- Cold urticaria. B- Mast cell activation syndrome. C- Physical urticaria. D- Raynaud phenomenon.

43-year-old man presents for evaluation of a persistent skin discoloration on his left lower leg. He reports that the lesion has been present for approximately 8 months and has remained relatively stable in size and appearance. He denies pain, ulceration, or bleeding, although he notes occasional mild pruritus. He does not recall preceding trauma, infection, or new medication use. He has no significant past medical history and denies systemic symptoms. On examination, there is a solitary, well-demarcated, golden-brown to rust-colored patch on the medial aspect of the left lower leg measuring approximately 2 cm in diameter. The lesion has a smooth surface without scale, induration, or atrophy. No palpable purpura or surrounding erythema is present. There are no similar lesions elsewhere on the body. The remainder of the skin examination is unremarkable. What is the most likely diagnosis? A- Lichen aureus B- Schamberg disease C- Pityriasis rubra pilaris D- Mycosis fungoides

A 49-year-old man visited his doctor about a pruritic skin lesion that developed on his hand a few weeks prior. On dermatologic examination, a macerated plaque with peripheral peeling scale was seen at the finger web on his right hand. The patient worked as a dishwasher and had a history of diabetes mellitus. He appeared well and reported no systemic symptoms. Potassium hydroxide (KOH) examination showed the presence of yeasts. What's the diagnosis? A- Chromoblastomycosis B- Erosio interdigitalis blastomycetica C- Majocchi granuloma D- Tinea manus

24-year-old woman presents for evaluation of a skin lesion on her right thumb. She reports noticing the discoloration several days after returning from a vacation to the Caribbean. During the trip, she frequently prepared and drank margaritas while spending time outdoors in direct sunlight, and recalls handling fresh limes. She denies any trauma, pain, pruritus, or prior similar eruptions. She also denies fever or other systemic symptoms and has no history of photosensitive skin disorders. On examination, there is a well-demarcated, irregularly shaped, hyperpigmented patch on the dorsal aspect of the right thumb with a subtle linear and geometric configuration. There is no associated erythema, vesiculation, blistering, scaling, or ulceration. The surrounding skin appears normal, and the remainder of the skin examination is unremarkable What is the most likely diagnosis? A- Phytophotodermatitis B- Eczema C- Idiopathic guttate hypomelanosis D- Tinea

Weekly Challenge: A patient presented multiple erythematous papules and nodules, many crusted, in a primarily truncal distribution. A 24-year-old man visited his doctor with fever, joint pain, and painful cyst-like lesions that were progressive for the preceding few weeks. On dermatologic examination, there were multiple erythematous papules and nodules, many crusted, in a primarily truncal distribution that covered his neck, back, and chest. When asked about medications and drug use, the patient admitted that he had been taking anabolic-androgenic steroids (AAS) / testosterone for 5 months prior to lesion presentation. What's the diagnosis? A- Acne fulminans B- Acne vulgaris C- Folliculitis D- PFAPA syndrome

A 77-year-old man presents for evaluation of a chronic skin lesion on his right lower leg. He first noticed the lesion several years ago, with very gradual enlargement over time. He denies rapid growth, bleeding, ulceration, or significant pain, although he notes occasional mild pruritus. His medical history is notable for a squamous cell carcinoma on the left forearm that was excised 1 year ago without recurrence. He has a history of long-term sun exposure related to outdoor work and denies systemic symptoms. On examination, there is an annular, well-demarcated plaque on the anterior aspect of the right lower leg measuring approximately 1.5 cm in diameter. The lesion demonstrates a thin, raised, hyperkeratotic peripheral ridge with central hypopigmentation and mild atrophy. The border has a subtle brownish scale and is more prominent than the center. No ulceration, nodularity, or surrounding erythema is present. No similar lesions are identified elsewhere on the skin, and the remainder of the skin examination is unremarkable. What is the most likely diagnosis? A- Psoriasis B- Nummular eczema C- Porokeratosis D- Tinea

71-year-old man presents with localized pain along the lateral aspect of his right fourth finger after working in the yard several months ago. He recalls a brief, sharp injury at the time and reports persistent tenderness since then, particularly when gripping objects or applying pressure to the area. He notes mild swelling but denies drainage, numbness, fever, or other systemic symptoms. His tetanus immunization status is uncertain.On physical examination, there is focal erythema and mild edema along the lateral side of the distal right fourth digit. There is also light brown linear discoloration beneath the skin surface. The area is tender to palpation without fluctuance or purulence. Sensation, capillary refill, and range of motion of the digit are intact. The remainder of the examination is unremarkable. What is the most likely diagnosis? A- Acute bacterial paronychia B- Felon (subcutaneous digital pulp infection) C- Cellulitis of the finger D- Retained cutaneous foreign body (splinter)

A 38-year-old woman presents with several weeks of asymptomatic discoloration on her shoulders and upper back. She first noticed faint light patches that gradually became more noticeable, particularly after sun exposure. She denies pain or pruritus but reports mild flaking when the areas are rubbed. She has no recent illness and denies use of new topical products or medications. She notes increased sweating during the summer months. On physical examination, multiple pinkish-white, oval-to-round, thin plaques are distributed symmetrically over the shoulders and upper back . The lesions have a thin, fine scale that becomes more apparent with gentle scraping. No erythema, induration, or excoriations are present. The remainder of the skin examination is unremarkable. What is the most likely diagnosis? A- Tinea versicolor B- Pityriasis alba C- Vitiligo D- Seborrheic dermatitis

A 41-year-old woman presents for evaluation of a pigmented lesion on the left side of her torso that has been present since birth. She reports that the lesion has enlarged proportionally with her body, slowly darkened slightly, and become slightly raised over time. She does not recall any recent rapid growth, bleeding, ulceration, pain, or pruritus. There is no personal or family history of skin cancer, and she reports no neurologic or systemic symptoms. On examination, there is a well-circumscribed, asymmetrically pigmented plaque on the left lateral torso measuring approximately 8 cm. The lesion shows variegated brown pigmentation with mild surface texture. No nodules, ulceration, or surrounding satellite lesions are noted. The remainder of the skin examination is unremarkable. What is the most likely diagnosis? A- Epidermal nevus B- Pigmented seborrheic keratosis C- Congenital nevus D- Melanoma

An 84-year-old woman with no significant past medical history presents for routine dermatologic evaluation; her last total body skin examination was 3 years earlier. She denies any personal or family history of skin cancer. Physical examination reveals a 1 x 1 cm papule with focal pigmentation on the right buttock. Dermoscopy shows a well-circumscribed, flesh-colored papule with blue-black pigmentation, surrounded by translucent-pink areas with telangiectatic vessels. There is no evidence of keratinization or scaling . What is the most likely diagnosis? A- Basal cell carcinoma B- Pigmented trichoblastoma C- Intradermal nevus D- Neurofibroma