Medallion-like dermal dendrocyte hamartoma: a new clinically and histopathologically distinct lesion.

Dermal dendrocyte hamartomas are extremely rare; only two examples have been described with clinical features different from our cases and with incomplete immunohistochemical characterization. We report three female patients presenting a medallion-shaped, well-defined, slightly atrophic and asymptomatic congenital lesion. All 3 patients showed a fusiform-cell proliferation. Immunohistochemistry was positive for CD34, factor XIIIa, and fascin. Electron microscopy showed typical features of dermal dendrocytes. We believe that the lesions described represent a new, clinically and histopathologically distinct lesion originating in dermal dendrocytes. We propose to name it medallion-like dermal dendrocyte hamartoma.