Grayish brown macules on the axillae, lower abdomen, and groin.

A 4-year-old boy presented with a slightly pruritic, erythematous, ill-defined, 3 3-cm plaque on his scalp associated with overlying alopecia developing 4 months before presentation (Figure 1). Findings from physical examination were otherwise unremarkable. Potassium hydroxide smear for dermatophytes was negative. A punch biopsy was obtained from the lesion and submitted for dermatopathologic study (Figure 2 and Figure 3). What is your diagnosis?