Men with breast enlargement may be caused by physiological natural changes in hormones, or may be caused by drug factors and pathological factors such as testicular seminomas. 1. Physiological factors: such as newborn boys can be due to high maternal estrogen levels, resulting in the role of estrogen to promote the development of the mammary glands dominate the role of estrogen, resulting in the development of mammary gland hyperplasia. In addition to puberty or old age of men, can be caused by hormone imbalance secretion of mammary gland hyperplasia development. 2. Drug factors: some drugs such as isoniazid, spironolactone, etc. have a similar structure or effect with estrogen, which may stimulate the mammary glands and lead to hyperplasia after taking them. 3. Pathological factors: such as testicular spermatogonia, pituitary tumor, congenital testicular hypoplasia, liver failure, hyperthyroidism, androgen sensitivity syndrome can cause estrogen and androgen secretion disorders in the male body, resulting in the development of mammary gland hyperplasia. Men with breast hyperplasia are advised to go to the hospital in time to improve the examination of liver and kidney function, breast and testis, etc., and find out the cause and then actively treat it to avoid delaying the condition.