Tenosynovial cysts are cystic swellings that occur in the tendon sheaths of the joints and are caused by degeneration of the connective tissue in the joint capsule, ligaments, and tendon sheaths. The cyst contains a colorless, clear or orange, yellowish, thick mucus with a dense, hard, fibrous connective tissue wall. The cysts are usually unicompartmental and occur on the dorsum of the wrist and dorsum of the foot. The etiology is unknown and may be related to chronic trauma. It can be caused by injury, excessive strain (especially in the hands and fingers), osteoarthritis, some systemic immune diseases, or even infection. Long-term repetitive joint activities in occupations such as typists, cargo handling or industries that require long hours of computer operation can trigger or aggravate the disease. 1.General symptoms Tenosynovial cysts can occur at any age, mostly in youth and middle age, more women than men. The cysts are slow growing, round, and generally do not exceed 2 cm in diameter. There are also sudden findings. In some cases, there is no conscious discomfort except for the local mass, and sometimes there is mild pressure pain. Most cases have localized soreness or discomfort that affects activity. The size of the cyst is not directly related to the severity of symptoms, but to the tension of the cyst, the greater the tension, the harder the swelling and the more obvious the pain. 2.Local symptoms （1）Tendon sheath cysts in the wrist occur mostly on the dorsal side of the wrist, and a few on the palmar side. The best site is at the dorsal joint capsule of the wrist joint on the radial side of the common extensor tendon, followed by between the radial wrist flexor tendon and the long thumb extensor tendon. (2) Tendon sheath cysts in the foot and ankle are more common in the dorsalis pedis tendon sheaths, which mostly originate from the tendon sheath of the long toe extensor tendon lateral to the dorsalis pedis artery.