Ganglion cysts are lumps that form under the skin, usually on top of the wrist, but may occur elsewhere on the hands, ankles and feet. They are usually round or oval shape and may vary from the size of a pea to about an inch in diameter.
They are noncancerous, balloon-like, fluid-filled structures that form along a joint or tendon. Their cause is unclear but may be related to gymnastics, osteoarthritis, or a previous joint or tendon injury.
They are typically not painful but may impair movement. In about half the cases, ganglion cysts go away by themselves. If the cyst is painful or restricts movement, a physician may either drain it with a needle or remove it surgically. In both cases, cysts may return.