In addition to directly stimulating breast tissue growth, estrogens indirectly decrease secretion of testosterone by suppressing luteinizing hormone secretion, resulting in decreased testicular secretion of testosterone. Estrogen excess
One of the main mechanisms for imbalance between estrogens and androgens is the overproduction of estrogens. A possible cause may be a neoplasm that originates from estrogen-secreting cells. Tumors that produce hCG stimulate production of estradiol while reducing other testicular hormone production. Obesity is another common cause of excess serum estrogens due to the presence of aromatase in peripheral tissue, which is a protein that converts androgens into estrogens. Peutz-Jeghers syndrome is a rare cause of testicular tumors that affect aromatase expression, which results in elevated serum estrogen levels. Aromatase excess syndrome is a rare genetic disorder that leads to increased conversion of androgens to estrogens in the body. Androgen deficiency
Primary hypogonadism (indicating an intrinsic problem with the testes in males) leads to decreased testosterone synthesis and increased conversion of testosterone to estradiol potentially leading to a gynecomastic appearance. Klinefelter syndrome is a notable example of a disorder that causes hypogonadism and gynecomastia, and has a higher risk of breast cancer in males (20–50 times higher than males without the disorder). Secondary hypogonadism (indicating a problem with the brain) leads to decreased production and release of luteinizing hormone (LH, a stimulatory signal for endogenous steroid hormone synthesis) which leads to decreased production of testosterone and estradiol in the testes.
Dimpling of the skin, nipple discharge, and nipple retraction are not typical features of gynecomastia and may be associated with other disorders. Milky discharge from the nipple is not a typical finding, but may be seen in a gynecomastic individual with a prolactin secreting tumor. An increase in the diameter of the areola and asymmetry of the chest are other possible signs of gynecomastia.Gynecomastia has psychosocial implications that may be particularly challenging for adolescents who are experiencing physical maturation and self-identity formation, which includes body image disturbances, negative attitudes towards eating, self-esteem problems, social withdrawal, anxiety, and shame. Men with gynecomastia may appear anxious or stressed due to concerns about its appearance and the possibility of having breast cancer. Causes
Gynecomastia is thought to be caused by an altered ratio of estrogens to androgens mediated by an increase in estrogen action, a decrease in androgen action, or a combination of these two factors. Estrogen and androgens have opposing actions on breast tissue: estrogens stimulate proliferation while androgens inhibit proliferation. The cause of gynecomastia is unknown in around 25% of cases. Known causes can be physiologic (occurring normally) or non-physiologic due to underlying pathologies such as drug use, chronic disease, tumors, or malnutrition. Physiologic
Physiologic or normal gynecomastia can occur at three timepoints in life: shortly after birth in both female and male infants, during puberty in adolescent males, and in older adults over the age of 60. Newborns
60-90% of male and female newborns may show breast development at birth or in the first weeks of life.