Male mammary gland hyperplasia is caused by excessive hyperplasia of male mammary gland tissue and matrix, which is usually benign and mostly physiological in neonatal period, adolescence and old age. The vast majority of adolescent male mammary gland hyperplasia can naturally subside, but 25% patients can last for 2 years or longer. Breast hyperplasia in adolescent males may be caused by the imbalance of serum estrogen and androgen in adolescence, or by the increased sensitivity of breast tissue to free estrogen and androgen at physiological level. Most adolescent male mammary gland hyperplasia does not need special treatment. However, when hyperplasia of mammary glands can not subside, causing pain or anxiety and pain in children, affecting daily life, drugs or surgical treatment should be considered. Adolescent male mammary gland hyperplasia needs to be diagnosed by a doctor in a regular hospital, especially for children with obvious mammary gland hyperplasia before puberty. The following diseases should be ruled out-

1. Tumors: tumors that secrete steroid hormones such as adrenal gland or testis, and tumors that secrete HGG and prolactin tumor; 2. Androgen resistance syndrome, hyperthyroidism, obesity, congenital adrenal seborrhea and other endocrine diseases.