A hard bag on the wrist is not a normal performance, may be common warts, dermatofibroma, tendon sheath cysts, keloid bumps caused. 1. common warts: common warts are caused by human papilloma virus infection of the skin mucous membrane, is a benign proliferative skin disease, can occur in any part of the body, can also occur in the wrist, resulting in local hard bumps. 2. Dermatofibroma: Dermatofibroma is a benign tumor of dermal fibroblast proliferation, which may occur in the limbs, but also in the wrist. It causes localized round, hard, dark brown or reddish brown nodules. 3. Tendon sheath cysts: Tendon sheath cysts are common orthopedic chronic diseases that are localized benign swellings. It may form a mass on the surface of the body. When the mass is small, the patient may not have any symptoms, and as the mass grows, it may become sore and swollen. 4. Keloid: keloid is caused by excessive proliferation of connective tissue in the skin, is a benign skin mass, initially small red spots with itching, gradually from small to large, from soft to hard. There are many other reasons for a hard lump on the wrist (such as superficial lipoma), it is recommended to go to the hospital dermatology, orthopedics, first to find the cause, and then targeted treatment.