The treatment of 40-year-old male breast development is as follows: 1, etiological treatment, if it is drug-induced gynecomastia, should stop applying the relevant drugs. If it is caused by other diseases, the original disease should be actively treated. 2, drug treatment, sex hormone treatment should take a cautious attitude, so as not to apply improperly and cause hormone level disorders in the body, limited to clinical symptoms are more obvious. 3, surgical treatment, for obvious pain, drug treatment effect is not obvious, observation after one year without subsiding, surgical excision treatment can be carried out, generally taken to retain the nipple subcutaneous mastectomy, make an incision along the edge of the areola, if the incision exceeds the periareolar area, the incision will be made in the periareolar area. Excision, make incision along the edge of areola, if the incision is more than 50% around the areola, it is easy to cause nipple blood supply obstacle, need to pay attention to retain a certain thickness of subcutaneous tissue at the base of the nipple, not only to ensure the blood supply of the nipple, but also to prevent the deformity of localized depression of the nipple after the excision of the mammary gland.