Report of an angiosarcoma mimic: cutaneous aneurysmal fibrous histiocytoma.

Aneurysmal fibrous histiocytoma is an unusual variant of the spectrum of fibrous histiocytomas with the peculiar morphologic appearance of a benign aneurysmal vasoformative process that ultimately culminates in multiple microhemorrhages within the tumor. It looks strikingly different from the usual cutaneous lesions encountered in clinical dermatology practice. A single report of a cutaneous aneurysmal fibrous histiocytoma in the skin of the back of a 60-year-old male is described with emphasis on the immunostaining pattern and review of the literature. There is a significant potential for confusion of this lesion with other cutaneous lesions, clinically as well as pathologically. In our case, the patient presented with a lesion that clinically resembled a hemangioma, was pathologically interpreted initially to be an angiosarcoma, and finally, the revised pathology was interpreted as an aneurysmal variant of a fibrous histiocytoma. Caution is warranted to avoid misinterpretation of cutaneous fibrohistiocytic tumors.