Gynecomastia, or gynaecomastia, is the development of abnormally large mammary glands in males resulting in breast enlargement, which can sometimes cause secretion of milk.

The condition is customary that can be diagnosed by examination by a physician. Sometimes, imaging by X-rays or ultrasound is needed to confirm the diagnosis.

Treating the underlying outcome of the gynecomastia may lead to improvement in the condition. Patients must talk with their doctor about revising any medications that are found to be causing gynecomastia; often, an alternative medication can be found that avoids gynecomastia side-effects, while still treating the primary condition for which the original medication was found not to be suitable due to causing gynecomastia side-effects (e.g., in place of taking spironolactone the alternative eplerenone can be used.) Selective estrogen receptor modulator medications, such as tamoxifen and clomiphene, or androgens or aromatase inhibitors such as Letrozole are medical treatment options, although they are not universally approved for the treatment of gynecomastia.

Breast prominence can result from hypertrophy of breast tissue, chest adipose tissue and skin, and is typically a combination. Breast prominence due solely to excessive adipose is frequently termed pseudogynecomastia or sometimes lipomastia.

Physiologic gynecomastia occurs in neonates, at or before puberty and with aging. Numerous cases of gynecomastia are idiopathic, meaning they have no clear cause. Possible pathologic causes of gynecomastia are: medications including hormones, increased serum estrogen, decreased testosterone production, androgen receptor defects, chronic kidney disease, chronic liver disease, HIV, and other chronic illness. In 25% of cases, the cause of the gynecomastia is not known.

gynecomastia