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Dermatology · Viral infections
Sample itemA 6-year-old child has multiple small, pearly, dome-shaped papules with central umbilication on the trunk and in the axillae. What is the causative agent?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Molluscum contagiosum virus (a poxvirus)
Molluscum contagiosum is caused by a DNA poxvirus and spreads by direct contact and autoinoculation. Histology shows large intracytoplasmic molluscum (Henderson-Paterson) bodies. It is usually self-limiting in immunocompetent children.
Option by option
A. Human papillomavirus
Human papillomavirus causes warts, which are rough or hyperkeratotic rather than smooth, pearly and umbilicated.
B. Molluscum contagiosum virus (a poxvirus) (correct)
Correct. Umbilicated pearly papules are the hallmark of this poxvirus infection.
C. Herpes simplex virus
Herpes simplex virus causes grouped vesicles on an erythematous base.
D. Varicella-zoster virus
Varicella-zoster virus causes vesicles that appear in crops, not persistent pearly umbilicated papules.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.