Ganglion cysts are fluid-filled masses that can occur near joints and tendons.  They are very common, and generally harmless.  They can, however, be unsightly, painful, and annoying.  Bones come together at joints.  The ends of the bones are protected by cartilage where they fit together.  Each joint is surrounded by synovial tissue that forms a joint capsule.  Within the joint is synovial fluid which helps the bones to glide smoothly. Ganglion cysts are thought to form when the joint is irritated, causing an increase in the production of a clear, thick fluid known as mucin.  As pressure builds up within the joint, the fluid may push through a weak spot in the synovial tissue and form a pouch.  As more fluid is produced, more fluid is pushed through a stalk and into the cyst.  And so the cyst may fluctuate in size. Ganglion cysts are most common at the wrist but they can occur over other joints and tendons.  They may begin to put pressure on nearby structures, which can be painful.  They can also cause unsightly lumps. Treatment options depend on how much distress they cause.  They can be left alone if they are not very bothersome.  An attempt can be made to get rid of the cyst by aspirating the fluid out of the cyst through a needle.  A small amount of steroid may be injected at that time in an effort to reduce inflammation and prevent the cyst from reoccurring.  If the cyst returns, surgery may be discussed.  A small incision is made over the cyst.  The tissue around the cyst is dissected away to expose the stalk connecting the cyst to the joint.  The cyst is then removed at the stalk.  The incision is closed with sutures and a compression dressing is applied to the area for a few days. Occasionally, ganglion cysts return even after surgical excision.