JOINT GANGLION

saclike structure containing thick gelatinous material that appears on the top or underside of the wrist, or less commonly on the top of the foot. The cause is unknown, but trauma (wound or injury) to the tendon sheaths or the lining material of the joint may be implicated; it is most common in persons who use their hands and wrists constantly, as typists and pianists. The swelling develops slowly, causes little or no pain, and may disappear spontaneously. It may also be removed by surgery or be shrunk by injection of chemicals.