Atypical solitary fibrous tumor of the vulva.

An atypical solitary fibrous tumor (SFT) was encountered as a slow-growing, 15-cm, well-demarcated, vulvar tumor in a 70-year-old woman. The tumor was highly cellular and composed predominantly of hemangiopericytomatous and capillary hemangioma-like proliferations and short fascicular arrangements of spindled cells. Multinucleated giant cells and tumor necrosis also were present. The tumor cells were positive for vimentin, CD34, progesterone receptors, and bcl-2 and were diploid by flow cytometry. The patient was well without disease 9 months after surgery. Awareness of the occurrence of atypical SFT in the vulva is important so that confusion with other neoplasms can be avoided.