Retroperitoneal Synovial Sarcoma
As a very rare type of tumor, soft tissue sarcomas (STS) constitute only 1% of all malignancies. Synovial sarcoma morphologically mimics synovium during development. Synovial sarcoma mostly affects adults aged 30–60 years and accounts for 8–10% of all types of sarcomas. About 85–95% of this group of tumors arises from the extremities close to the large joints; and 5–15% occurs in the head and neck, mediastinum, abdominal wall, and retroperitoneum. Primary retroperitoneal synovial sarcoma is extremely rare, making up 0.8–8.3% of all synovial sarcomas. Meanwhile, retroperitoneal synovial sarcomas represent approximately 1% of all retroperitoneal tumors. The disease was firstly described by Pack and Tabah (1954); up to now, 35 cases in total have been reported.