What Is a Ganglion Cyst?
A ganglion cyst of the foot is a small lump that typically develops near a joint or tendon in the foot or ankle. The cyst is filled with fluid and is often round or oval-shaped. It can vary in size, from a pea-sized bump to a larger lump that is several centimeters in diameter. Ganglion cysts are typically harmless, but they can cause pain and discomfort if they press on a nearby nerve or interfere with movement in the foot or ankle. They may also cause cosmetic concerns, as they can be visible under the skin. Sometimes it is difficult to discern a ganglion cyst from an epidermal inclusion cyst or other cystic manifestation. The exact cause of ganglion cysts is unknown, but they are believed to develop when the tissue surrounding a joint or tendon becomes inflamed or irritated, causing the fluid-filled cyst to form.