Ganglions are small sacs (cysts) filled with clear, jellylike 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 fibers connecting muscle to bone). Most people with
ganglions notice that the bumps appear suddenly.
ByHealthwise Staff Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine Specialist Medical ReviewerHerbert von Schroeder, MD, MSc, FRCSC - Hand and Microvascular Surgery