CT and MR imaging of a huge retroperitoneal synovial sarcoma: A case report.

Retroperitoneal synovial sarcoma is extremely rare, with only a few cases reported in the literature. The diagnosis is often made late, due to anatomical considerations, with common symptoms including low back pain and weight loss. Imaging is critical for diagnosis, often revealing a heterogenous mass with the "triple sign" and calcifications. The main differential diagnoses include liposarcoma, undifferentiated pleomorphic sarcoma and leiomyosarcoma. Surgical resection remains the treatment of choice, though it is not always feasible, which contributes to the poor prognosis. The presented case is a retroperitoneal synovial sarcoma in a 29 years old man with findings from ultrasound, computed tomography and magnetic resonance imaging.