A ganglion is a small cyst filled with synovial fluid from around the joint.  These cysts can usually be seen at the back of the wrist.  It is usually painless, but excessive use of the hand or pressure to the ganglion may cause discomfort.

Ganglions may disappear on their own, but often return at a later date. If the ganglion is not painful and does not interfere with the use of the hand and wrist, no treatment is necessary.  If the ganglion becomes painful or large, your doctor may consider using a needle to aspirate, or withdraw fluid from the cyst.  Surgery to remove the ganglion may be necessary if aspiration of the fluid does not provide permanent relief.