Dermatologist Certificate General 3 — Questions and Answers
Question 1: A patient with HIV develops painful, grouped vesicles along a unilateral thoracic dermatome. What is the treatment of choice?
- Topical acyclovir
- Oral valacyclovir (Correct answer)
- Oral doxycycline
- Intravenous amphotericin B
Correct answer: Oral valacyclovir
Herpes zoster in immunocompromised patients is treated with oral valacyclovir or famciclovir; IV acyclovir is reserved for severe or disseminated disease.
Question 2: Which gene is most commonly mutated in patients with familial melanoma?
- BRAF
- CDKN2A (Correct answer)
- KIT
- NRAS
Correct answer: CDKN2A
CDKN2A (encoding p16/INK4A) is the most commonly mutated gene in familial melanoma, significantly increasing lifetime risk.
Question 3: Nikolsky's sign is positive in which of the following conditions?
- Bullous pemphigoid
- Pemphigus vulgaris (Correct answer)
- Dermatitis herpetiformis
- Epidermolysis bullosa acquisita
Correct answer: Pemphigus vulgaris
Nikolsky's sign — lateral pressure causing epidermal slippage — is positive in pemphigus vulgaris due to loss of keratinocyte cohesion from anti-desmoglein antibodies.
Question 4: Which topical medication is first-line for rosacea papulopustular subtype?
- Topical tretinoin
- Topical metronidazole (Correct answer)
- Topical betamethasone
- Topical mupirocin
Correct answer: Topical metronidazole
Topical metronidazole is a first-line treatment for papulopustular rosacea due to its anti-inflammatory and antimicrobial properties.
Question 5: The Koebner phenomenon refers to the appearance of skin lesions at sites of:
- Bacterial infection
- Trauma or injury (Correct answer)
- Sun exposure
- Allergic reaction
Correct answer: Trauma or injury
The Koebner (isomorphic) phenomenon occurs when skin disease appears at sites of trauma, classically seen in psoriasis, vitiligo, and lichen planus.
Question 6: A 35-year-old woman has butterfly-shaped facial erythema, photosensitivity, and a positive ANA. Which antibody is most specific for SLE?
- Anti-dsDNA (Correct answer)
- Anti-Ro (SSA)
- Anti-histone
- Anti-La (SSB)
Correct answer: Anti-dsDNA
Anti-dsDNA antibodies are highly specific for SLE and their titers often correlate with disease activity, particularly lupus nephritis.
Question 7: Which type of skin cancer has the highest rate of metastasis?
- Basal cell carcinoma
- Squamous cell carcinoma
- Merkel cell carcinoma (Correct answer)
- Sebaceous carcinoma
Correct answer: Merkel cell carcinoma
Merkel cell carcinoma is a rare but aggressive neuroendocrine skin cancer with high rates of local recurrence, nodal spread, and distant metastasis.
Dermatologist Certificate General 3
A patient with HIV develops painful, grouped vesicles along a unilateral thoracic dermatome.
What is the treatment of choice?