Ganglion arises from a weakness in a joint capsule or tendon sheath. This results in a swelling and eventually a cyst filled with synovial fluid. They are not dangerous and are mainly a cosmetic problem. Ganglion occurs most frequently among the young/middle-aged, and most often among women.
The cause is unknown. Wear and tear, and any previous injuries, probably play a role.
Many ganglions disappear on their own. The condition therefore needs no treatment. If a ganglion does not disappear, grows quickly, or causes problems, however, puncture and drainage may be appropriate. In rare cases, surgery is necessary.