Unusual Eruption on the Arm: Challenge
The patient reported a past medical history of hypertension and denied any history of hyperlipidemia. On physical examination, there were numerous slightly firm, smooth papules and plaques on the right upper arm. A skin biopsy was performed.
Hematoxylin and eosin–stained sections demonstrated a dense proliferation centered within the dermis and composed of histiocytes with ample foamy cytoplasm and a few multinucleated histiocytes. There was also black pigment distributed throughout the foamy cells (Fig. 1A–C).