Papular Eruption on a Patient With Down Syndrome—Quiz Case

A 39-year-old man with Down syndrome presented with a long-standing history of an eruption over his hands and arms. The eruption, which was completely asymptomatic, had been an incidental finding by his general practitioner, who had been treating him for a fungal toenail infection. Physical examination revealed a pigmented papular eruption that tended to occur in clumps on the lateral and medial aspects of the patient’s feet (Figure 1) as well as on his forearms (Figure 2). He also had dystrophy of his toenails.Theresultsof therestof theskinexaminationwere unremarkable.Apunchbiopsyspecimenwasobtainedfrom one of the lesions on the forearm (Figure 3). What is your diagnosis?