A cystic protrusion of the wrist is one of the symptoms of a tendon sheath cyst. Thecal cyst is the most common type of mass on the dorsal side of the wrist and can also occur on joint capsules and tendon sheaths in other parts of the body. Thecal cysts are characterized by a rounded shape, with no change in the appearance of the skin, and protrude from the skin surface. When compressed with the hand, they feel tough and elastic, like a rubber ball in the hand, and can be moved by pushing it. Tendon sheath cysts in the wrist: they occur mostly on the dorsal side of the wrist, and a few on the palmar side. The best site is the dorsal joint capsule of the wrist joint on the radial side of the common extensor tendon, followed by the radial wrist flexor tendon and the long thumb extensor tendon. Tenosynovial cysts on the palmar side of the carpal joint sometimes need to be differentiated from radial artery aneurysms, and the radial artery, cephalic vein, and superficial branches of the radial nerve should be protected when removing the cyst there. Cysts can also occur in the flexor tendon sheath in the carpal tunnel, compressing the median nerve and triggering carpal tunnel syndrome. A few tendon sheath cysts, the size of a grain of rice and as hard as cartilage, can occur on the flexor tendon sheaths of the fingers far from the metacarpophalangeal joint. The following two other abnormal changes are common in the carpal joint, which is the joint between the lower arm and the hand. (1) Round, soft masses characterized by softness to the touch and the ability to move back and forth, most commonly as fibrolipomas of the tendon sheath. (2) Nodular protrusions Characterized by nodular protrusions in the joint area that interfere with the normal movement of the wrist joint, commonly caused by rheumatic or tuberculosis osteochondritis. A cystic protrusion of the wrist joint can usually be resolved with outpatient surgery.