Dorsal wrist ganglion

Ganglions are small sacs (cysts) filled with clear, jelly-like fluid. They often appear as bumps on the hands and wrists, but they can also develop on the feet, ankles, knees, or shoulders. A ganglion can grow out of a joint capsule, which surrounds and protects the joint, or out of a tendon sheath, which covers the tendon (the ropey fibres connecting muscle to bone). Most people with ganglions notice that the bumps appear suddenly.