[Efficacy of preoperative radiation therapy in hyper-vascular solitary fibrous tumor]

The hyper-vascular form of solitary fibrous tumors (SFTs) is rare and there have been few therapeutic evaluations of this entity. We encountered a hyper-vascular SFT and had difficulty removing it surgically. Following radiotherapy, both tumor size and feeder vessels were reduced and we could proceed with gross total removal. A 29-year-old woman was admitted with a 1-year history of decreasing visual acuity on the right side. Magnetic resonance imaging with gadolinium enhancement showed a homogenous enhancing mass (6x5x5 cm) which expanded the superior and inferior tentorium cerebelli. The tumor was fed by the left posterior cerebral artery, bilateral middle meningeal arteries and the right occipital artery. The first operation employed an occipital transtentorial approach and a highly vascular tumor was found. Tumor resection was limited due to severe bleeding. Histologically, the tumor showed focal hypercellularity with spindle cells and numerous capillaries. Immunohistochemically, the tumor was diffusely positive for CD34 and a diagnosis of SFT, hyper-vascular subtype, was made. After the first operation, local irradiation of a total of 40 Gy was performed. Both the tumor size and vascularity decreased dramatically. At the second operation, gross total removal was able to be performed. Radiotherapy appears effective in reducing the hyper-vascular subtype of SFT and would be one possible therapy to deal with these tumors, given their propensity of excessive bleeding during initial surgery.