A ganglion is a soft tissue mass that most commonly occurs on the wrist in women between 25 and 45 years of age. They are also seen commonly on the foot. A ganglion is a firm, rubbery mass that occurs on the top of the foot. On the foot, the most common area of involvement is in front of the ankle or on the outside of the ankle. A common characteristic of a ganglion is that they will enlarge and then shrink is size. They generally occur without any apparent cause. Ganglions arise spontaneously from a weakness in the soft tissue covering of a joint or tendon sheath. Ballooning out of the tissue occurs and it fills with a thick mucoid fluid. In many instances, ganglions are not painful until they reach a size that causes irritation from shoe pressure. On occasion they will compress a nearby skin nerve and cause tingling into the top of the toes. Tapping on the ganglion will often result in this same tingling sensation into the toes. Other common masses on the foot are giant cell tumors, fibromas and lipomas.