A bulge on the thumb generally has the following causes: i. Tenosynovial cysts, repeated wear and tear of the tendon sheaths at the ends of the extremities, which tend to form cyst-like changes. The bulge has clear borders and a hard texture. If it is large or close to the joint, it can affect the normal activities of the finger and is accompanied by painful symptoms. At this time, surgical removal of the tendon sheath cyst or aspiration of the cystic fluid in the tendon sheath can be considered, followed by injection of hydrocortisone acetate and other drugs to promote the self-absorption of the cystic fluid. Second, when the patient’s hand is traumatized, if the skin around the thumb is accompanied by soft tissue injury, the formation of local hematoma may also be manifested as a bulge phenomenon. At this time, local ice packs can be applied for 24 hours, oral bruising pills, and topical application of blood-stasis cream after 24 hours to promote absorption of the hematoma and reduce pain and inflammatory reactions.