Q&A Medicine>>>>>Dermatology
Question 6#

An 18-month-old infant presents with a diffuse rash that has worsened over the past 24 hours. His mother reports that he has been lethargic with a decreased appetite. The child is otherwise healthy, but did have symptoms consistent with an upper respiratory infection a few weeks prior to the onset of the rash. Physical examination reveals an afebrile infant with the following dermatologic finding shown below.

Which of the following is the most common cause of this condition?

A. Drug reaction
B. Herpes simplex virus
C. Mycoplasma pneumoniae
D. Non-Hodgkin lymphoma

Correct Answer is B

Comment:

Herpes simplex virus. The patient in this question is presenting with pink-red papules and plaques with a pale central regions. The skin lesions have a “target” appearance, a classic description for erythema multiforme (EM). EM is a skin condition whose cause remains unclear but likely is secondary to immune complex deposition in superficial microvasculature of the skin. EM usually follows infection or drug exposure. The most common cause of EM is herpes simplex virus (HSV). (A, C, D) Drug reactions (sulfa drugs, phenytoin, β-lactam antibiotics), Mycoplasma pneumoniae, and non-Hodgkin lymphoma are also causes of EM, but not as common as HSV infection.