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. Although they most often occur on the wrist, they also frequently develop on the foot – usually on the top, but elsewhere as well. Ganglion cysts vary in size, may get smaller and larger, and may even disappear completely, only to return later.