Dermatologist Certificate MCQ Flashcards

A 45-year-old presents with a scaly, erythematous plaque with silver scale on the extensor surface of the elbow. The Auspitz sign is positive. What is the most likely diagnosis?

Answer: Psoriasis vulgaris

Auspitz sign (pinpoint bleeding when scale is removed) is characteristic of psoriasis vulgaris, commonly found on extensor surfaces.

Which dermatophyte species is the most common cause of tinea capitis in the United States?

Answer: Trichophyton tonsurans

Trichophyton tonsurans is the predominant cause of tinea capitis in the US, especially in African American children.

A newborn presents with vesicles and pustules on an erythematous base distributed over the trunk, face, and extremities. Smear shows eosinophils. What is the diagnosis?

Answer: Erythema toxicum neonatorum

Erythema toxicum neonatorum is a benign self-limiting eruption in newborns characterized by eosinophils on smear.

Which layer of the epidermis contains the highest concentration of melanocytes?

Answer: Stratum basale

Melanocytes reside primarily in the stratum basale (basal layer), where they transfer melanin to surrounding keratinocytes.

A patient taking methotrexate for psoriasis develops oral ulcers and cytopenias. Which supplement should be co-administered to reduce toxicity?

Answer: Folic acid

Folic acid supplementation reduces methotrexate-related side effects including mucositis and bone marrow suppression without significantly reducing efficacy.

Which type of hypersensitivity reaction underlies allergic contact dermatitis?

Answer: Type IV (delayed-type)

Allergic contact dermatitis is a Type IV (cell-mediated, delayed-type) hypersensitivity reaction involving sensitized T lymphocytes.

A 30-year-old woman presents with periorbital heliotrope rash and Gottron's papules over the knuckles. What is the most likely diagnosis?

Answer: Dermatomyositis

Heliotrope rash and Gottron's papules are pathognomonic features of dermatomyositis.