Tendon sheath cysts, which are not really tumors but can be classified as tumor-like disease or neoplastic lesions, are common masses in the hand. It mainly originates from synovial membrane, tendon sheath and tendon. The cause of occurrence is not well understood, but there is often a history of acute injury or repeated chronic trauma, and it may also be related to the nature of the occupation. It can occur at any age, but is more common in youth and middle age, and more common in women than men. The most common site is the dorsal aspect of the wrist, a round, oval, smooth, tough, mobile mass, some may be painful; the next most common site is the radial aspect of the wrist palm (i.e., at the pulse); there are also those occurring at the distal end of the palm or the proximal end of the fingers, which are often on the flexor tendon sheath, such as the size of a grain of rice, hard as bone. They are filled with a clear jelly-like mucus that is colorless or slightly yellowish. Cysts can appear suddenly or can grow slowly from small to large. They can disappear on their own after an external force or without significant external force and reappear later. No malignant transformation of tendon sheath cysts has been reported. There are several methods of treatment, but the efficacy is not satisfactory and the chance of recurrence is high. 1. Non-surgical treatment. Pinching or pressing with external force; syringe puncture, squeezing, etc., can make the cyst disappear, but there are more chances of recurrence. 2.Surgical treatment. Complete removal of the cyst. The chance of recurrence is lower than non-surgical treatment, but the recurrence rate is still higher than that of other common swellings after surgery.