Overview】 Tendon sheath cysts (ganglion) are 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. Etiology and pathogenesis】 The cause of the disease is unknown. Currently, most people believe that the cyst is formed by degenerative changes in the connective tissue on the joint capsule, ligament and tendon sheath due to local malnutrition. Some cases are related to trauma. Tendon sheath cysts have a dense fibrous connective tissue wall with no lining cells and a colorless, clear, gelatinous mucus inside the cyst, and the cavity is mostly single-roomed, but there are also multi-roomed cases. The cyst is closely related to the joint capsule or tendon sheath. Some people believe that the cyst cavity is connected to the joint cavity or the synovial cavity of the tendon sheath, while others believe that it is only connected to the root and not to each other. Diagnostic points】 Clinical manifestations Tenosynovial cysts can occur at any age, but are more common in youth and middle age, and more in women than men. They are most often seen on the dorsal surface of the wrist, followed by the palm of the wrist, the palm of the hand and the dorsal surface of the foot, and can also occur on both sides of the knee and in the N fossa. The growth of cysts is slow, but they are also found suddenly. A few of them may disappear spontaneously and may grow again later. In some cases, there is no conscious discomfort except local swelling, and most cases have local swelling and pain or discomfort. The cyst on the palm side of the hand has squeezing pain when holding the object. On examination, a smooth shaped, tense mass with mild pressure pain can be felt. There is a cyst-like or fluctuating sensation. When the tension is high, the mass is sometimes mistaken for a bony protrusion. A tendon sheath cyst on the palmar side of the wrist or palm of the hand may compress the ulnar or median nerve and cause sensorimotor deficits.