A synovial sarcoma is a type of cancer called a soft tissue sarcoma.

Soft tissue sarcomas develop from supportive tissues in the body including connective tissue, muscle and fat. There are many different types.

Synovial sarcomas start from cells similar to those that make up the tissue which lines the joints of the body, the synovium. But synovial sarcoma cells do not actually start in the synovium.

Synovial sarcomas make up about 1 in 20 of all soft tissue sarcomas and are commonest in the limbs (arms and legs). They can also develop in the tissues of the muscle wall of the chest and abdomen.

Synovial sarcomas usually start as a quickly growing, painless swelling.

The usual treatment for a synovial sarcoma is surgery. Sometimes this is followed by radiotherapy, to reduce the chance of the cancer coming back. Occasionally a synovial sarcoma is too large or attached to surrounding body tissues to remove with an operation. In this situation, radiotherapy or chemotherapy may be given to try to shrink the sarcoma and make an operation possible.

If the synovial sarcoma is in a part of the body where surgery is impossible, or dangerous, radiotherapy is used. This is often combined with chemotherapy, as synovial sarcomas often respond well to chemotherapy.