A 19-year-old Japanese man presented with a 4-year history of asymptomatic eruptions in both axillae. He was otherwise healthy, and there was no family history of skin lesions.
On physical examination, there were multiple 1- to 3-mm light-brown papules in both axillae (Figure 1). The papules were discrete, with some tendency to grouping and a linear arrangement. They were not associated with the roots of the hair. A small number of similar papules were found at the periphery of a pubic hair lesion in the lower abdominal area. The face and chest were not involved. The results of routine laboratory tests were normal. A topical steroid (diflucortone valerate) was applied, without effect, so a biopsy was performed (Figure 2).