Adolescent boys with large breasts can be categorized as either physiological or pathological, and physiological gynecomastia can usually recover on its own. 1. Physiological gynecomastia: includes early childhood, puberty and old age. Gynecomastia during puberty is mainly due to the exuberant secretion of sex hormones during puberty, which lasts from a few months to a few years, and most of them will return to normal at the end of puberty. 2. Pathological breast development: including excessive secretion of estrogen, such as testicular tumors; low secretion of androgen, such as testicular hypoplasia; androgen receptor insensitivity; and other reasons. To go to the hospital in time to carry out relevant examinations, for example, due to testicular tumors caused by excessive secretion of estrogen, to check the liver function in time, and relevant treatment, most of the diseases are cured after treatment. Adolescent boys with large breasts should go to the hospital in time to determine the cause of breast development, and follow the medical advice for treatment.