Cysts are fluid filled masses under the skin. Common cysts of the feet include synovial cysts, ganglia and cutaneous mucoid cysts.

Most foot cysts are located under the skin, although occasionally they may be found in tendon or bone. The synovial or ganglionic cysts are connected to a nearby joint or tendon, are harder to treat.

Mucoid cysts are not connected to a joint; if they are located near the nail, they may cause the nail to grow improperly.

Most cysts are mildly painful because of pressure created by your shoes. When the cyst encloses or presses on a nerve, it can cause a sharp pain.

Some cysts form as a result of repeated injury to your foot. Ganglion cysts may be treated by numbing the area and extracting the fluid inside. A steroid or hardening agent may then be injected into the cyst to try to prevent it from filling again. Loose fitting comfortable shoes are likely your best preventative measure.