Trans-sacral resection of a solitary fibrous tumor in the pelvis: report of a case.

Solitary fibrous tumors (SFTs) develop most commonly in the pleura, although they have occasionally been reported to arise in the pelvic cavity. We report a case of an SFT presenting as a painless nodule in the pelvis of a 56-year-old woman. Histologically, the tumor was composed of spindle-shaped cells arranged without pattern, with short and narrow fascicles and interspersed bundles of thick collagen, and numerous blood vessels with a focally hemangiopericytoma-like appearance. Immunohistochemically, the tumor cells strongly expressed vimentin, CD34, and bcl-2. The tumor was excised via a trans-sacral approach, without preoperative transcatheter embolization, and the patient remains well more than 2 years after her operation. To our knowledge, this is the first case of an SFT in the pelvis, which was excised completely via a trans-sacral approach.