Synovial sarcoma is a malignant soft tissue tumor that develops from undifferentiated mesenchymal cells. It is relatively common, following malignant fibrous histiocytoma, liposarcoma, and rhabdomyosarcoma in prevalence.
There is a slight male predilection and a peak incidence between 15 and 35 years of age.
Only 10% of synovial cell sarcomas are within a joint. Usually they are located adherent to a joint capsule, bursa, fascia, or tendon sheath. They are most common in the lower extremity.
Synovial sarcoma has low to intermediate signal inten-sity on T1-weighted MR images and heterogeneous high signal intensity on T2-weighted images. This tumor is often multilocular with internal septation, and occasionally fluid-fluid levels are seen. Calcifications are present in 308 of cases and are best seen On a scans. The presence of extensive calcification indicates a better prognosis.