It is also called “gynecomastia”. It refers to the development and enlargement of one or both sides of the male breast like the female breast, sometimes with milk-like secretions. It often occurs in adolescence and is a normal phenomenon that can gradually return to normal in 1-2 years without treatment. Most of the reasons for its occurrence are unknown, but a few patients may be caused by endocrine disorders. Because gynecomastia and congenital testicular hypoplasia coexist, individual patients have feminine features. Gynecomastia is also seen in patients with hepatic insufficiency, vitamin B deficiency, and some patients on long-term hormone therapy. Gynecomastia differs histologically from gynecomastia in that there are no milk-producing glandular lobules present, only hyperplasia of the fibrous and fatty tissues of the milk ducts and cystic enlargement of the milk ducts. For gynecomastia, there is no need to treat it urgently. However, for those with excessive volume that cannot be retracted in adulthood, affecting the aesthetic appearance of the patient and increasing the patient’s psychological burden, surgical correction can be considered. The surgery is performed under local anesthesia, and a semicircular incision is made at the lower edge of the areola to remove the enlarged breast tissue. If there is too much skin, a crescent-shaped skin can be removed at the incision site, leaving the nipple and areola intact. Postoperative pressure bandages are applied for 5-7 days. In recent years, many doctors have used the technique of fat aspiration for the treatment of gynecomastia, i.e., making small incisions in the inframammary folds, inserting a suction tube, and using the principle of negative pressure: sucking the breast tissue out of the body.