Disease Definition: Solitary fibrous tumor (SFT), also known as fibrous tumor of the pleura, is a rare mesenchymal tumor originating in the pleura or at virtually any site in the soft tissue including seminal vesicle. Approximately 78% to 88% of SFT's are benign and 12% to 22% are malignant. It is a heterogeneous group of rare spindle-cell tumors that include benign and malignant neoplasms. Their cell of origin is still debated. SFT is preferred by most pathologists as a better term than “hemangiopericytoma” that gathers numerous unrelated entities and is presently only employed by neuropathologists. We focus the present paper on the forms of this family of tumors occurring in adult patients. There are 3 typical primary locations: pleural, meningeal and extrathoracic soft tissue.
Disease Symptoms: Patients present with proptosis and possibly ptosis, eyelid swelling, tearing, diplopia or decreased vision. Malignant infiltrating lesions can sometimes cause pain.
Disease Treatment: Because even benign-appearing solitary fibrous tumors (SFTs) can be locally recurrent and metastatic, wide resection of both benign and malignant SFTs is recommended. Preoperative vascular studies and arterial embolization should be considered because of the known bleeding risk with resection. Careful exclusion of other diagnoses (eg, synovial sarcoma) is important. Because of the favorable outcome with SFTs, it may be possible to avoid limb-threatening and deforming operations. No evidence suggests that adjuvant chemotherapy is beneficial. If the SFTR appears malignant histologically, adjuvant radiation therapy may be considered. Long-term follow-up is recommended because local and distant relapse is possible, even with benign-appearing tumors.
Statistics: Patients (n=103) with resected primary solitary fibrous tumor were identified (excluding meningeal tumors). The most common sites of occurrence were abdomen and pleura; these tumors were larger than those occurring in the extremities, head and neck or trunk, but did not demonstrate significant outcome differences. Overall 5- and 10-year metastasis-free rates were 74 and 55%, respectively, while 5- and 10-year disease-specific survival rates were 89 and 73%. A risk stratification model based on age, size, and mitotic index clearly delineated patients at high risk for poor outcomes. While small tumors with low mitotic rates are highly unlikely to metastasize, large tumors ≥15 cm, which occur in patients ≥55 years, with mitotic figures ≥4/10 high-power fields require close follow-up and have a high risk of both metastasis and death.