Dermatologist Certificate Dermatologist Certificate MCQ 2 — Questions and Answers
Question 1: 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?
- Psoriasis vulgaris (Correct answer)
- Seborrheic dermatitis
- Lichen planus
- Pityriasis rosea
Correct answer: Psoriasis vulgaris
Auspitz sign (pinpoint bleeding when scale is removed) is characteristic of psoriasis vulgaris, commonly found on extensor surfaces.
Question 2: Which dermatophyte species is the most common cause of tinea capitis in the United States?
- Microsporum canis
- Trichophyton tonsurans (Correct answer)
- Epidermophyton floccosum
- Trichophyton rubrum
Correct answer: Trichophyton tonsurans
Trichophyton tonsurans is the predominant cause of tinea capitis in the US, especially in African American children.
Question 3: 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?
- Neonatal herpes simplex
- Erythema toxicum neonatorum (Correct answer)
- Staphylococcal scalded skin syndrome
- Transient neonatal pustular melanosis
Correct answer: Erythema toxicum neonatorum
Erythema toxicum neonatorum is a benign self-limiting eruption in newborns characterized by eosinophils on smear.
Question 4: Which layer of the epidermis contains the highest concentration of melanocytes?
- Stratum corneum
- Stratum granulosum
- Stratum basale (Correct answer)
- Stratum spinosum
Correct answer: Stratum basale
Melanocytes reside primarily in the stratum basale (basal layer), where they transfer melanin to surrounding keratinocytes.
Question 5: A patient taking methotrexate for psoriasis develops oral ulcers and cytopenias. Which supplement should be co-administered to reduce toxicity?
- Vitamin B12
- Vitamin D
- Folic acid (Correct answer)
- Zinc
Correct answer: Folic acid
Folic acid supplementation reduces methotrexate-related side effects including mucositis and bone marrow suppression without significantly reducing efficacy.
Question 6: Which type of hypersensitivity reaction underlies allergic contact dermatitis?
- Type I (IgE-mediated)
- Type II (cytotoxic)
- Type III (immune complex)
- Type IV (delayed-type) (Correct answer)
Correct answer: Type IV (delayed-type)
Allergic contact dermatitis is a Type IV (cell-mediated, delayed-type) hypersensitivity reaction involving sensitized T lymphocytes.
Question 7: A 30-year-old woman presents with periorbital heliotrope rash and Gottron's papules over the knuckles. What is the most likely diagnosis?
- Systemic lupus erythematosus
- Dermatomyositis (Correct answer)
- Psoriatic arthritis
- Mixed connective tissue disease
Correct answer: Dermatomyositis
Heliotrope rash and Gottron's papules are pathognomonic features of dermatomyositis.
Dermatologist Certificate Dermatologist Certificate MCQ 2
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?