Solitary fibrous tumor of all sites: outcome of late recurrences in 14 patients

Background: We explore the pattern of late recurrence (LR) in solitary fibrous tumor (SFT), focusing on histopathologic characteristics, clinical presentation and patients (pts) outcome. Methods: Clinical records of all pts with confirmed pathologic diagnosis of SFT treated at our Institution from 2005 to 2011 were reviewed. We analysed the data of pts who relapsed >= 10 years after initial diagnosis. Results: A total of 14 pts were identified. The primary site of origin was pleura (5 pts), pelvis (4 pts), head and neck (3 pts) and retroperitoneum (2 pts). Primary tumor was a typical SFT in 5 and a malignant SFT in 7 out of 12 pts whose tumor tissue was available for revision. The median time to first recurrence was 12 years (range 10-23). The first relapse was local in 11 cases, distant in 3. Five pts later developed distant metastases. Four out of 5 cases of typical SFT developed distant metastases in spite of their initial benign aspect. No patient was disease-free at the time of the analyses. Conclusion: Our series suggests that LR can occur in SFT and some cases can behave aggressively even in the absence of any primary morphologic evidence of malignancy. A prolonged follow-up may be advisable.