Tendon sheath cysts can compress local nerves and cause local sensory-motor deficits, such as compression of the ulnar nerve. Tendon sheath cysts can also affect joint flexion and extension, such as dorsal wrist cysts that limit wrist motion and popliteal cysts that limit knee motion. Tendon sheath cysts are commonly found in the hands and feet, especially in the dorsal wrist, and are non-neoplastic in origin. Tendon sheath cysts have a white dense fibrous connective tissue wall and a colorless, clear, jelly-like mucus content that sometimes communicates with the joint or tendon sheath cavity. Tendon sheath cysts can occur at any age, mostly in young adults, and are most common on the back of the wrist. The clinical manifestation is a localized hard or tough round swelling, mostly painless, slow-growing, and with light pressure pain. Treatment, conservative treatment can forcefully compress the cyst to make it disappear, some patients will be cured, surgical excision, such as cystectomy is a good treatment with low local recurrence rate.