Solitary fibrous tumors in the central nervous system. A clinicopathologic review of 18 cases and comparison to meningeal hemangiopericytomas.

CONTEXT: Solitary fibrous tumors (SFTs) of the central nervous system are rare neoplasms that usually present as dura-based masses and clinically resemble meningiomas. Histologically, they can be similar to fibrous meningioma or hemangiopericytoma (HPC). In particular, densely cellular regions seen in some SFTs can be indistinguishable from HPC. Little is known about the biological behavior of SFTs, although most seem amenable to total resection.
OBJECTIVES: To define the clinicopathologic spectrum of SFTs in the central nervous system and to outline their differences from HPC and meningioma.
DESIGN: We present the clinicopathologic features of 18 patients with SFT and compare them with those of an age- and sex-matched cohort of HPCs.
RESULTS: Eleven SFTs were supratentorial, 3 were infratentorial, and 4 were intraspinal. Four of the 18 tumors were intra-axial (2 in the lateral ventricles and 2 within the spinal cord). Histologically, SFTs were similar to their soft tissue counterparts. Six tumors (6/18) had densely cellular regions, and 1 tumor showed frankly anaplastic features. All but 3 patients underwent gross total resection, and there were no metastases or tumor-related mortalities during the median follow-up of 40 months. In contrast, there were 15 local recurrences (83%), 5 extracranial metastases (27%), and 4 tumor-related deaths (22%) in the HPC cohort.
CONCLUSIONS: Our study presents the clinicopathologic features of SFT as a distinct entity from both meningioma and HPC. We also present unusual examples of anaplastic, intraventricular, and intramedullary spinal SFTs that expand the clinicopathologic spectrum of these uncommon and sometimes diagnostically difficult neoplasms.