A ganglion is a fluid-filled swelling of the lining of a joint or tendon. They can form on any area of the foot, but are most commonly seen on the ankle or top of the foot. Ganglions are caused by repeated irritation that weakens the lining of the joint or tendon. Those who wear boots or other heavy footwear are more vulnerable to ganglions.
There are not always other symptoms present with ganglions, but some of the most common signs are:
A thorough examination is important, because ganglions can be mistaken for tumors. Surgery involves removing the ganglion and its surrounding tissue. Pain, swelling, and numbness can occur while you recover, and recovery lasts for a few weeks.