Pigmented hidroacanthoma simplex: A diagnostic pitfall

Hidroacanthoma simplex (HAS) is a rare skin appendage tumor and is recognized as an intraepidermal variant of poroma. Pigmented HAS is an extremely rare variant with dendritic melanocytes and/or melanin pigment in the tumor cells and a few cases of pigmented HAS have been reported in the English literature. We herein report a case of pigmented HAS and discuss the clinicopathological features of pigmented HAS and the pitfall in the diagnosis of black lesions.