Routine hematoxylin-eosin–stained slides showed a dome-shaped, umbilicated lesion with a central erosion. Collections of histiocytes and sparse perivascular infiltrates of lymphocytes were present within the dermis directly underlying the erosion. In the deeper aspects of the dermis, there was a rare focus where the histiocytes formed a palisading granuloma.
A therapeutic trial of hydroxychloroquine (6 mg/kg per day) was instituted because of the generalized distribution of the lesions. After 3 months of therapy, all but the lesions on the dorsal aspect of the hand had regressed, leaving only hypopigmentation. The medication was well tolerated, with no adverse effects.