Medallion-like dermal dendrocyte hamartoma.

Medallion-like dermal dendrocyte hamartomas are rare congenital cutaneous lesions, with only three occurrences reported in the English language literature. They present at birth as asymptomatic circular, oval, or triangular well-circumscribed, atrophic patches. Typically, they have an erythematous or yellow-brown hue and a characteristic pliable, wrinkled surface; subtle telangiectases may also be appreciated. They may be misdiagnosed as atrophoderma, cutis aplasia, or anetoderma. All reported patients have been female. Characteristic histologic findings include epidermal atrophy and the presence of a CD34-positive spindle cell proliferation in the dermis. This spindle cell proliferation represents a population of dermal dendrocytes, which are bone marrow-derived cells that are believed to function as antigen-presenting cells that contribute to the function of the skin immune system. Little is known about the pathophysiology of medallion-like dermal dendrocyte hamartomas. We present a patient with this entity and review similar presentations reported in the literature.