Trauma-induced simulator of targetoid hemosiderotic hemangioma.

Reported here is a 15-year-old with lesions demonstrating histologic features of targetoid hemosiderotic hemangioma (THH) developing after trauma to inflammatory lesions. These lesions pose as simulators of THH. Targetoid hemosiderotic hemangioma is a benign vascular lesion first described by Santa Cruz and Aaronburg. It classically presents as a single, small, red/brown, targetoid lesion on the trunk or extremities of a young or middle-aged individual. Histologically, it is characterized by ectatic vascular lumina in the papillary dermis lined by a single layer of endothelial cells with an epithelioid or "hobnail" appearance. In the deeper dermis, vascular spaces become slit-like and angulated, appearing to dissect through collagen bundles. A commonly proposed etiology of THH is trauma to a preexisting hemangioma. This case is remarkable for its unusual clinical presentation, histologic simulation of THH, and for its support for the theory that trauma can induce the histologic changes seen in THH.