PANRE Dermatology 3 — Questions and Answers
Question 1: A 45-year-old with HIV (CD4 count 80) presents with verrucous, cauliflower-like plaques on the trunk unresponsive to topical antifungals. Biopsy shows intracytoplasmic inclusion bodies (Henderson-Paterson bodies). What is the diagnosis?
- Disseminated histoplasmosis
- Molluscum contagiosum (Correct answer)
- Cryptococcosis
- Condyloma acuminata
Correct answer: Molluscum contagiosum
Molluscum contagiosum in severely immunocompromised patients (CD4 <200) can present atypically as large, widespread plaques; Henderson-Paterson bodies are pathognomonic on biopsy.
Question 2: A neonate develops a desquamating rash starting around the mouth and spreading to form large flaccid bullae that rupture to leave a scalded appearance. Nikolsky sign is positive. Which toxin is responsible?
- Staphylococcal toxic shock toxin-1
- Staphylococcal exfoliative toxin A/B (Correct answer)
- Streptococcal pyrogenic exotoxin A
- Clostridium perfringens alpha toxin
Correct answer: Staphylococcal exfoliative toxin A/B
Staphylococcal scalded skin syndrome is caused by exfoliative toxins A and B from S. aureus, which cleave desmoglein-1 in the superficial epidermis.
Question 3: A 60-year-old woman with rheumatoid arthritis on methotrexate develops painless, white, lacy streaks on the buccal mucosa and violaceous, polygonal, flat-topped papules on the wrists. What is the most likely diagnosis?
- Secondary syphilis
- Lichen planus (Correct answer)
- Psoriasis
- Pityriasis rosea
Correct answer: Lichen planus
Lichen planus classically presents with the 6 P's: pruritic, polygonal, planar, purple papules and plaques, often with Wickham's striae on mucosal surfaces.
Question 4: A 35-year-old woman notes symmetric hyperpigmented patches on her cheeks and upper lip that worsen during summer and pregnancy. She is on oral contraceptives. What is the recommended first-line treatment?
- Topical hydroquinone 4% + sun protection (Correct answer)
- Topical tretinoin 0.1% alone
- Chemical peel with TCA 25%
- Laser therapy with Q-switched Nd:YAG
Correct answer: Topical hydroquinone 4% + sun protection
Hydroquinone 4% combined with strict photoprotection is first-line for melasma; the triple combination (hydroquinone + tretinoin + mild corticosteroid) is more effective for resistant cases.
Question 5: Which dermoscopic finding is most specific for melanoma?
- Comma-shaped vessels
- Atypical pigment network with regression (Correct answer)
- Arborizing telangiectasias
- Milium-like cysts
Correct answer: Atypical pigment network with regression
An atypical pigment network with irregular meshwork combined with regression structures (white scar-like areas, blue-gray peppering) is highly specific for melanoma on dermoscopy.
Question 6: A 50-year-old man with type 2 diabetes presents with velvety, hyperpigmented skin in the axillae and posterior neck. Which condition is most associated with this finding?
- Confluent and reticulated papillomatosis
- Acanthosis nigricans (Correct answer)
- Erythrasma
- Terra firma-forme dermatosis
Correct answer: Acanthosis nigricans
Acanthosis nigricans is strongly associated with insulin resistance and type 2 diabetes, presenting as velvety hyperpigmentation in body folds.
Question 7: A 28-year-old woman develops targetoid lesions (concentric rings) on her palms and oral erosions 10 days after starting trimethoprim-sulfamethoxazole for a UTI. She has no systemic symptoms. What is the diagnosis?
- Stevens-Johnson syndrome
- Erythema multiforme major
- Toxic epidermal necrolysis
- Erythema multiforme minor (Correct answer)
Correct answer: Erythema multiforme minor
Erythema multiforme minor presents with typical target lesions on acral surfaces and may involve one mucosal surface without systemic symptoms or significant epidermal detachment.
PANRE Dermatology 3
A 45-year-old with HIV (CD4 count 80) presents with verrucous, cauliflower-like plaques on the trunk unresponsive to topical antifungals.
Biopsy shows intracytoplasmic inclusion bodies (Henderson-Paterson bodies).
What is the diagnosis?