Solitary fibrous tumors of the central nervous system: report of five cases with unusual clinicopathological and outcome patterns

Abstract

This is a retrospective study of 11 patients harboring a solitary fibrous tumor (SFT) of the central nervous system (CNS), with special emphasis on unusual clinicopathological and outcomes patterns. Between 2000 and 2008, 11 patients harboring CNS SFTs were treated at our institution. Patient charts were retrospectively reviewed and tumor location, clinical presentation, imaging characteristics, extent of resection, dural origin, pathological features, adjuvant treatment, and follow-up data were collected, focusing on five atypical cases (four intracranial and one within the spine). One intracranial SFT arose from the sella turcica and relapsed threefold during the 6 years following partial removal. Disease progressed as successive isolated local recurrences treated by subsequent surgical interventions and gamma-knife radiosurgery. The MiB-1 labeling index analysis showed a steady increase in these sequential recurrences (ranging from less than 3% up to 6%) without obvious malignant transformation. The second SFT occurred in the cerebellopontine angle and exhibited a high MiB-1 index (10%) without noticeable features of malignancy. It relapsed twice during the 5 years following gross total resection without demonstrating a more aggressive histological pattern. The third SFT arose from the cerebellar tentorium, widely invaded the lateral sinus and adjacent bone, had a low MiB-1 index, and has not recurred within the 2 years after incomplete resection. The two remaining SFTs presented with unusual clinicoradiological features. We described a extremely rare case of intraventricular SFT, and a case of extradural SFT of the thoracic spine (T8-T9) radiologically consistent with a schwannoma. Immunohistochemistry confirmed that all tumors were SFTs. These atypical presentations gave us the opportunity to provide further information about the variability of the clinicoradiological patterns and natural histological course of CNS SFTs.