Ganglion cyst removal, or ganglionectomy, is the removal of a fluid-filled sac on the skin of the wrist, finger, or sole of the foot. The cyst is attached to a tendon or a joint through its fibers and contains synovial fluid, which is the clear liquid that lubricates the joints and tendons of the body. The surgical procedure is performed in a doc tor's office. It entails aspiration, or draining fluid from the cyst with a large hypodermic needle. The cyst may also be excised (removed by cutting).

From http://www.surgeryencyclopedia.com/Fi-La/Ganglion-Cyst-Removal.html