A ganglion cyst is a non-cancerous change, or cyst, within a joint or tendon that appears as soft, round lumps. These cysts are made up of small spaces filled with mucous fluid and are surrounded by thickened fibrous tissue. They are usually under three centimeters in size. Most ganglion cysts develop in the wrist, but they may also develop around the small joints in the hands, as well as in the ankle and foot.
Doctors do not know why ganglion cysts develop. One theory is that they form from long-standing damage to the supporting tissue around a joint (the joint capsule), which weakens the tissue, and leads to the formation of small spaces called cysts.
Ganglion cysts may develop in anyone but are most commonly found in women between 20 to 50 years of age. Why women develop ganglion cysts more frequently than men is not totally understood but estrogen may play a role as it has been shown to increase the risk for joint damage in other conditions. Prior trauma to the area, repetitive stress injury to a nearby joint, and arthritis may increase the risk of developing a ganglion cyst. For instance, ganglion cysts are frequently seen in the wrists of gymnasts.
The diagnosis is usually made after the ganglion cyst is removed in a minor surgical procedure. The tissue is sent to a pathologist for examination. Under the microscope, ganglion cysts are made up of small spaces filled with mucous fluid and surrounded by thickened fibrous tissue. Although the word “cyst” appears in the name, ganglion cysts are technically considered “pseudocysts” because unlike true “cysts” the spaces are not lined by specialized epithelial cells.
Ganglion cysts usually shrink and disappear without treatment over time. As a result, a ganglion cyst can simply be observed if it is not causing pain or discomfort. A surgical excision (a procedure that removes all the abnormal tissue) is the main treatment option for patients who experience ongoing symptoms. Aspiration, or draining, of the ganglion cyst fluid, can also be performed, however, it results in a higher rate of recurrence.