COMSAE Dermatology and Integumentary System 2 — Questions and Answers
Question 1: A 40-year-old woman presents with facial flushing, erythema across the nose and cheeks, telangiectasias, and papulopustules. She reports flares with sun exposure, hot beverages, and alcohol. Which diagnosis is most likely?
- Systemic lupus erythematosus
- Rosacea (Correct answer)
- Perioral dermatitis
- Seborrheic dermatitis
Correct answer: Rosacea
Rosacea is characterized by central facial erythema, flushing, telangiectasias, and papulopustules triggered by heat, alcohol, spicy food, and UV exposure.
Question 2: A 50-year-old presents with greasy, yellowish scales on the scalp, nasolabial folds, and eyebrows. Which organism is implicated in the pathogenesis of seborrheic dermatitis?
- Staphylococcus epidermidis
- Malassezia furfur (Correct answer)
- Trichophyton tonsurans
- Candida albicans
Correct answer: Malassezia furfur
Malassezia furfur (a lipophilic yeast) colonizes sebaceous areas and triggers an inflammatory response causing seborrheic dermatitis.
Question 3: A 70-year-old farmer presents with an indurated, erythematous nodule on the lower lip that ulcerates and does not heal. Biopsy shows malignant squamous cells with keratin pearls. Which risk factor is most strongly associated with this diagnosis?
- BRCA1 gene mutation
- Chronic UV radiation exposure (Correct answer)
- Human papillomavirus type 16 infection
- Immunosuppression from organ transplant
Correct answer: Chronic UV radiation exposure
Squamous cell carcinoma of the lip and skin is most strongly associated with chronic UV radiation exposure, particularly in fair-skinned, outdoor workers.
Question 4: A 28-year-old develops widespread pruritic wheals of various sizes that resolve within 24 hours without leaving bruising or scarring. She denies systemic symptoms. Which mechanism is responsible?
- T-cell mediated cytotoxicity
- IgE-mediated mast cell degranulation releasing histamine (Correct answer)
- Immune complex deposition in dermal vessels
- Complement-mediated lysis of keratinocytes
Correct answer: IgE-mediated mast cell degranulation releasing histamine
Urticaria is caused by IgE-mediated mast cell degranulation releasing histamine and other mediators, causing transient wheals that resolve without trace.
Question 5: A 19-year-old started trimethoprim-sulfamethoxazole for a urinary tract infection. Three weeks later she develops widespread erythematous targetoid lesions involving mucosal surfaces, with epidermal detachment >30% of the body surface area. Which condition best describes this presentation?
- Erythema multiforme major
- Toxic epidermal necrolysis (TEN) (Correct answer)
- Pemphigus vulgaris
- Bullous pemphigoid
Correct answer: Toxic epidermal necrolysis (TEN)
Toxic epidermal necrolysis (TEN) is a severe drug reaction with epidermal detachment >30% BSA and mucosal involvement, most commonly triggered by sulfonamides and anticonvulsants.
Question 6: A 60-year-old presents with a rough, scaly, erythematous macule on the dorsum of the hand. The lesion is described as a premalignant condition with potential to progress to squamous cell carcinoma. Which is the most likely diagnosis?
- Seborrheic keratosis
- Actinic keratosis (Correct answer)
- Lentigo simplex
- Dermatofibroma
Correct answer: Actinic keratosis
Actinic keratosis is a premalignant lesion caused by chronic UV exposure that can progress to squamous cell carcinoma if untreated.
Question 7: A 35-year-old presents with flaccid bullae that rupture easily, leaving raw erosions. The Nikolsky sign is positive. Direct immunofluorescence shows IgG deposits in a 'fishnet' pattern throughout the epidermis. Which diagnosis is most likely?
- Bullous pemphigoid
- Pemphigus vulgaris (Correct answer)
- Dermatitis herpetiformis
- Linear IgA bullous dermatosis
Correct answer: Pemphigus vulgaris
Pemphigus vulgaris is characterized by IgG autoantibodies against desmoglein 1 and 3, causing suprabasal acantholysis, flaccid bullae, and a positive Nikolsky sign.
COMSAE Dermatology and Integumentary System 2
A 40-year-old woman presents with facial flushing, erythema across the nose and cheeks, telangiectasias, and papulopustules.
She reports flares with sun exposure, hot beverages, and alcohol.
Which diagnosis is most likely?