Ganglion cyst of the foot being drained out!! A ganglion cyst is a sac filled with a jellylike fluid that originates from a tendon sheath or joint capsule. The word “ganglion” means knot and is used to describe the knot-like mass or lump that forms below the surface of the skin. Ganglion cysts are among the most common benign soft-tissue masses. They are not harmful or cancerous, although they may cause discomfort and tingling, burning, numbness, aching, or pain if they are on or near a nerve. A