A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. Onset is often over several months, typically with no further symptoms. Occasionally, pain or numbness may occur. Complications may include carpal tunnel syndrome. The cause is unknown. The underlying mechanism is believed to involve an outpouching of the synovial membrane. Risk factors include gymnastics activity. Diagnosis is typically based on examination with light shining through the lesion being supportive. Medical imaging may be done to rule out other potential causes. Treatment options include watchful waiting, splinting the affected joint, needle aspiration, or surgery. About half the time, they resolve on their own. About three per 10,000 people newly develop ganglion of the wrist or hand a year. They most commonly occur in young and middle-aged females. Presentation The average size of these cysts is 2.0 cm, but excised cysts of more than 5 cm have been reported. The size of the cyst may vary over time and may increase after activity. Between 50 and 70% of all masses on the hand and wrist are expected to be ganglion cysts. Sites Ganglion cysts most frequently occur around the dorsum of the wrist and on the fingers. A common site of the occurrence is along the extensor carpi radialis brevis, as it passes over the dorsum of the wrist joint. Although most commonly found in the wrist, ganglion cysts also may occur in the foot. Ganglion cysts are "commonly observed in association with the joints and tendons of the appendicular skeleton, with 88% 'in communication with the multiple small joints of the hand and wrist' and 11% with those of the foot and ankle". Wrist They commonly are found near the wrist joint, especially at the scapholunate area. Common wrist ganglions include: dorsal wrist ganglion volar wrist ganglion volar retinaculum ganglion extensor retinaculum ganglion occult ganglion intraosseous ganglion mucous cyst Foot In a 2007 study of patients in Glasgow whose foot lumps were removed surgically, 39 of 101 cases were ganglion cysts. The study replicated earlier findings that no ganglion cysts were found on the sole or heel. The authors wrote, "Although lumps in these areas may be ganglia, the surgeon should probably consider other diagnoses in the first instance." The researchers noted a preponderance of occurrence among females (85%) and