Gynecomastia is most often seen in young men during puberty, but can also be seen in adults. The main clinical manifestations are female-like developmental enlargement of one or both male breasts, sometimes with lactic discharge, and sometimes pain with pressure. Some patients may have other diseases, such as pseudohermaphroditism, hypospadias, cryptorchidism, or benign or malignant tumors of the adrenal glands. It is generally believed that this is due to an imbalance in the ratio of estrogen to androgen in the body, resulting in a relative increase in estrogen concentration, which causes hyperplasia and development of breast tissue. Physiologic gynecomastia can be seen in newborns, adolescents, and older adults. Pathologically, it can occur in congenital absence of testes, Klinefelter’s syndrome (a disease of small testes), testicular feminization, Reifenstein’s syndrome (an incomplete male pseudohermaphroditism), viral orchitis, post-traumatic testicular atrophy, true hermaphroditism, testicular tumors, a specific type of lung cancer, adrenal tumors, hyperthyroidism, severe hepatitis and cirrhosis or B vitamin deficiency; gynecomastia can also occur from various causes of impaired inactivation of estrogen in the body, long-term application of drugs such as androstadienone, isoniazid and maundyphus, long-term use of estrogen drugs due to prostate cancer or prostate hyperplasia, and application of exogenous estrogen after sex reassignment surgery. Occasionally, there is a familial onset, but whether there is a genetic aspect to the condition requires further study. In terms of treatment, for patients with mild hyperplastic hypertrophy of the breast occurring in early adolescence, surgery can be avoided as most patients’ symptoms will disappear on their own after 1 to 2 years. However, if the hypertrophy of the breast is excessive or does not disappear after 1 to 2 years, it is important to seek medical help and have it surgically removed. The surgery uses a combination of fat aspiration from the developing breast area and glandular excision, which has been clinically proven to achieve satisfactory results. Moreover, the incision is small, with only a small curved incision at the edge of the areola, which is not easily detectable. The procedure is relatively safe, with little bleeding, and compression in an elastic undershirt for one month after surgery. It should also be noted that in addition to routine physical examination before surgery, it should be determined whether there are other aspects of disease, such as cryptorchidism, pseudohermaphroditism, hypospadias, or benign or malignant tumors of the adrenal glands. Postoperatively, antibacterial antibiotics are routinely applied and stitches are removed in 7 days.