What is it?
A ganglion cyst is a fluid-filled swelling that usually develops near a joint or tendon. The cyst can range from the size of a pea to the size of a golf ball. They can occur near any joint but are most common on the wrist, hands and fingers. Ganglion cysts look and feel like a smooth lump under the skin.
Ganglions are harmless, but can sometimes be painful. If they do not cause any pain or discomfort, they can be left alone and may disappear without treatment, although this can take a number of years.
See picture. An example of a right wrist with a dorsal ganglion.