When a firm, slowly growing mass appears near a tendon of the foot or ankle and does not fit the description…

When a firm, slowly growing mass appears near a tendon of the foot or ankle and does not fit the description of a simple ganglion cyst or lipoma, one important diagnosis to consider is a Giant Cell Tumor of the Tendon Sheath. This is a benign but locally aggressive soft tissue tumor that arises from the synovial lining of tendon sheaths — the protective tissue that surrounds and lubricates tendons as they glide through their tunnels