Gynecomastia (GYN) is commonly referred to as the feminization of the male breast. In small cases, flat, round nodules can be palpated just under the skin of the areola, while in large cases, the breasts are almost like those of adult women. There is usually tenderness and sometimes a lactic discharge. It can occur for a variety of reasons and can be classified as physiologic, pathologic, idiopathic, or pharmacologic. It can occur at any age. However, its clinical significance varies significantly at different ages. It occurs in infancy, adolescence and old age is often physiological (normal development of secondary sexual characteristics). The marked breast enlargement in male infants in infancy —– is considered normal, probably as a result of the parenchymal action of placental estrogen on the infant breast, but this process lasts only a few weeks. Adolescence —— It is estimated that mastopexy occurs in about 2/3 of adolescent males and that most of it occurs between the ages of 14 and 15. Virtually all adolescent boys have had this transient physiological change of mastopexy, but by the age of 20, few males experience mastopexy again. Common pubertal gynecomastia can be explained by plasma estradiol and associated testosterone – estrogen synthesized prior to the secretion of large amounts of testosterone by the testes, which promotes the development of gynecomastia. Aging phase – Plasma testosterone declines and luteinizing hormone (LH) rises as we enter old age, and as testosterone declines, the plasma androgen/estrogen ratio also declines. As we age, this change in normal hormonal composition leads to the development of gynecomastia in older men. Gynecomastia in prepubertal age is very rare and common causes include: adrenal disease, pituitary adenoma, thyroid disease, testicular tumors, 11-hydroxylase deficiency, familial gynecomastia, tuberous sclerosis, and partial precocious puberty. If gynecomastia occurs at other ages, especially if it occurs suddenly, without a history of specific drug use or drug abuse, and increases rapidly, it is more likely to be pathological. In particular, attention should be paid to the possibility of tumors with endocrine hormonal components (most commonly lung cancer). Other pathological causes include testicular insufficiency or hypotension, liver disease with hormone inactivation disorders, and prostate disease treated with estrogen; rare causes include Kallman syndrome, hypopituitary hypofunction, hypothalamic, pituitary or pineal tumors, hyper- or hypothyroidism, and chronic malnutrition. A variety of drugs can cause gynecomastia, including omeprazole, cimetidine, captopril, isoniazid, and ambrisentin. This is a pharmacological factor in male breast development, but it is usually possible only with long-term use. There is also a specific type of exogenous sex hormone intake. For example, drug use, marijuana being the most common type, and oral or injections of some testosterone or its precursors in young men who are keen on fitness can also cause mammary gland feminization. Most patients with mastopexy do not require treatment, especially since adolescent mastopexy has a high degree of self-limitation. Most patients disappear on their own within 1 to 2 years of onset. If the onset of the disease is due to estrogen use, it will gradually subside after stopping the medication. If there are speed symptoms such as pain, postoperative methyltestosterone can be taken orally 3 times a day at 5 mg for about one month. Only if: it does not subside for more than 2 years, the breast enlargement is obvious and affects the aesthetics medication is ineffective; those with symptoms; suspected cancer. Surgery should be considered only if the patient requires surgery. The goal of surgery is to reduce the volume of the breast and remove excess skin. Surgical procedures for gynecomastia can be broadly divided into three types: fat aspiration, sharp excision and fat aspiration combined with sharp excision. ①Simple fat aspiration is suitable for patients with predominantly fatty hyperplasia, and the small amount of remaining breast tissue will not affect the shape of the breast. ②For patients with predominantly parenchymal hyperplasia, the hyperplastic breast parenchyma is difficult to be removed by suction ducts and only sharp excision can be performed. The traditional procedure is to make a large incision in the upper or lower outer breast crease of the hyperplasia and remove the hyperplastic breast tissue after freeing the flap. The incision is concealed and has the advantages of low incidence of postoperative hematoma, nipple necrosis and nipple sensory disorder and small postoperative scar, which can avoid leaving obvious scar on the chest wall. For patients with more fatty tissues and more substantial glands, our department adopts minimally invasive lumpectomy technology to complete the operation (liposuction and gland excision) through tiny incisions in hidden areas that are not easy to detect, and the scars are basically invisible after the operation, which is often called “scarless surgery”. As a symbol of minimally invasive surgery, the application of lumpectomy in breast surgery is a typical example of the advanced treatment concept of organic combination of disease treatment and cosmetic psychology, which meets the requirements of the times for male breast development patients to be both healthy and beautiful.