Soft tissue sarcomas can develop from soft tissues like fat, muscle, nerves, fibrous tissues, blood vessels, or deep skin tissues. There are approximately 50 types of soft tissue sarcomas, including synovial sarcoma, a cancer of the connective tissue around joints. The most common locations are the hip, knee, ankle, and shoulder. Synovial sarcoma accounts for approximately 6% to 10% of all soft tissue sarcomas. Approximately one-third of synovial sarcomas occur in childhood and the peak incidence is in the third decade of life.