e22522 Background: Solitary fibrous tumor (SFT), a rare variant of soft tissue sarcoma (STS), is characterized by the presence of a NAB2-STAT6 fusion. Given the orphan character of SFT we performed a retrospective analysis. Methods: We retrospectively reviewed all patients (pts) with SFT treated in our institution between 12/1990 - 09/2017. Results: We identified 94 SFT pts (incl. hemangiopericytoma) with a med. follow-up for 4.7 yrs. Common anatomic sites were chest (33%), abdomen (21.3%), brain (12.8%) and extremities (9.6%). The symptomatology at diagnosis was variable. Only 6.4% presented with synchronous metastasis. Hypoglycemia (Doege-Potter syndrome) was seen in 2.1% of cases. A resection of the primary SFT was done in 86 pts (91.5%), their disease-free survival was 35.5 mo and 43% stayed SFT-free during follow-up. Local recurrence occurred in 26.7% of cases, associated with a med. overall survival (OS) of 45.1 mo. Metachronous metastasis was seen in 30.2% of pts, occurring after a med. follow-up of 36 mo. Med. OS after diagnosis of metastasis was 19.0 mo. Systemic therapy was given to 92.9% of pts with inoperable/metastatic disease. The most common 1^st line therapy was doxorubicin single agent (57.7% of pts), achieving responses in 13.3% of pts. 2^nd line therapies included ifosfamide and pazopanib (31.3% of pts each), 3^rd line treatment was very heterogeneous. Conclusions: SFT is an orphan malignancy with a variable clinical course, low incidence of distant spread at first diagnosis but considerable risk of local failure and metachronous metastasis. Surgery is the only curative option at diagnosis, time of relapse and in case of resectable metastasis. Palliative systemic therapy is considered in pts with inoperable/metastatic disease but achieves low response rates. The natural course and survival outcomes of SFT cases treated with palliative intent tend to be better than in non-selected STS pts.