Atypical presentations of solitary fibrous tumors of the central nervous system: an analysis of unusual clinicopathological and outcome patterns in three new cases with a review of the literature.

Central nervous system (CNS) solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms recognized less than a decade ago. Approximately 60 cases of SFT have been reported in the central nervous system. We describe three atypical SFTs of the CNS, two intracranial and one within the spine. One intracranial SFT arose from the sella turcica and expanded into the suprasellar areas. It relapsed twice during the 3 years following partial resection, and the MiB 1 labeling index steadily increased without obvious malignant transformation. The second SFT arose from the confluence of the sinuses, widely invaded the lateral sinus and adjacent bones, had a low MiB 1 index and has not recurred after 5 years. The intraspinal tumor occurred at T5-T7 in a patient with multiple café-au-lait spots, was predominantly myxoid and developed a second similar lesion at S3-S5 14 years later. The MiB 1 index was lower in the second tumor. Immunohistochemistry confirmed that all were SFTs. These atypical presentations gave us an opportunity to provide further information about the natural histological course of CNS SFTs.