Synovial sarcoma is a rare type of cancer that tends to occur near large joints, mainly the knees. Synovial sarcoma usually affects young adults.

Synovial sarcoma begins as a growth of cells that can multiply quickly and destroy healthy tissue. The first symptom is usually swelling or a lump under the skin. The lump may or may not hurt.

Synovial sarcoma can occur almost anywhere in the body. The most common places are in the legs and arms.

Synovial sarcoma is a type of cancer called a soft tissue sarcoma. These cancers happen in the body's connective tissues. There are many types of soft tissue sarcoma.

Synovial sarcoma is usually slow growing, so it can be years before a diagnosis is made. Sometimes, synovial sarcoma is diagnosed in error as a joint problem, such as arthritis or bursitis.

Tests and procedures used to diagnose synovial sarcoma include:

• Imaging tests. Imaging tests take pictures of the body. They can show where a synovial sarcoma is, how large it is and if it has spread to other areas of the body. Tests for synovial sarcoma might include MRI scan, X-ray and CT scan.

• Removing a sample of tissue for testing, also called biopsy. A biopsy is a procedure to remove a sample of tissue for testing in a lab. The tissue might be removed using a needle that is put through the skin and into the cancer. Sometimes surgery is needed to get the tissue sample.

  The sample is tested in a lab to see if it is cancer. Other special tests give more details about the cancer cells. Your health care team uses this information to make a treatment plan.

Treatment options for synovial sarcoma include:

• Surgery. Surgery is the main treatment for synovial sarcoma. The goal is to remove the cancer and some of the healthy tissue around it. This can sometimes mean the removal of an entire muscle or muscle group.

  In the past, surgery might have included removing an arm or leg, known as amputation. But medical advances have made amputation less likely.

  To lower the chances of the cancer returning, radiation therapy or chemotherapy might be used as well.

• Radiation therapy. Radiation therapy uses powerful energy beams to kill cancer cells. During radiation therapy, you lie on a table while a machine moves around you. The machine directs radiation to precise points on the body.

  Radiation before surgery can shrink the cancer and make surgery success more likely. Radiation therapy after surgery can kill cancer cells that are still there.

• Chemotherapy. Chemotherapy uses strong medicines to kill cancer cells. For synovial sarcoma, chemotherapy might be used before or after surgery. It also may be used when cancer has spread to other parts of the body.
• Targeted therapy. Targeted therapy uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die or stop growing. Targeted therapies are being studied for advanced synovial sarcoma.
• Clinical trials. Clinical trials are studies of new treatments. These studies provide a chance to try the latest treatment options. The side effects may not be known. Ask your health care team if there is a clinical trial available to take part in.