Ganglion cysts are non-cancerous fluid-filled lumps (cysts) that most commonly develop along the tendons or joints of your wrists or hands. They may also appear in your feet.
A ganglion cyst may develop suddenly or gradually over time. The exact cause is unknown. In many cases, ganglion cysts will cause you no pain and require no treatment. Often, they go away on their own. When you do need treatment for a ganglion cyst — due to pain or interference with joint movement or for cosmetic concerns — it usually consists of removing the fluid from the ganglion cyst or surgically removing the cyst.