Ganglion Cysts of the Hand
A cyst is a fluid-filled sac. 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 can disappear in time.
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 can decrease in size.