Ganglion cysts arise from the capsule of a joint or the sheath of a tendon. They can be found at different places on the wrist. A ganglion cyst that grows on the top of the wrist is called a dorsal ganglion. Others are found on the underside of the wrist between the thumb and your pulse point, at the end joint of a finger, or at the base of a finger. Most of the time, these are harmless and will often disappear in time.

A ganglion cyst contains a thick, clear, mucus-like fluid similar to the fluid found in the joint. No one knows what triggers the formation of a ganglion. Women are more likely to be affected than men. Ganglia are common among gymnasts, who repeatedly apply stress to the wrist.

Because the fluid-filled sac puts pressure on the nerves that pass through the joint, some ganglion cysts may be painful. Large ganglia, even if they are not painful, are unattractive. Smaller ganglions that remain hidden under the skin (occult ganglions) may be quite painful.

A ganglion grows out of a joint, like a balloon on a stalk. It rises out of the connective tissues between bones and muscles. Inside the balloon is a thick, slippery fluid similar to the fluid in your joints. Usually, the more active the wrist, the larger the cyst becomes. With rest, the lump generally decreases in size.

Your doctor may ask you how long you have had the ganglion, whether it changes in size, and whether it is painful. Pressure may be applied to identify any tenderness. A penlight may be held up to the cyst to see whether light shines through. X-rays may be taken to rule out other conditions, such as arthritis or a bone tumor. Sometimes, an MRI or ultrasound is needed to find a ganglion cyst that is not visible.

Initial treatment is not surgical.

• Observation. Because the ganglion is not cancerous and may disappear in time, just waiting and watching may be enough to make sure that no unusual changes occur.
• Immobilization. Activity often causes the ganglion to increase in size. This is because activity increases pressure on nerves, causing pain. A wrist brace or splint may relieve symptoms, letting the ganglion decrease in size. As pain decreases, your doctor may prescribe exercises to strengthen the wrist and improve range of motion.
• Aspiration. If the ganglion causes a great deal of pain or severely limits activities, the fluid may be drained from it. This procedure is called "aspiration." The area around the ganglion cyst is numbed and the cyst is punctured with a needle so that the fluid drains away.

Nonsurgical treatment leaves the outer shell and the stalk of the ganglion intact, so it may reform and reappear.

The ganglion cyst can be removed through outpatient surgery, but this is no guarantee that the cyst will not grow again. Surgery may also include removing part of the involved joint capsule or tendon sheath. There may be some tenderness, discomfort, and swelling after surgery. Normal activities usually may be resumed two to six weeks after surgery.