gynecomastia
(GY-neh-koh-MAS-tee-uh)
The abnormal growth of breast gland tissue in males. Gynecomastia in infants and boys may be caused by an imbalance in certain hormones. It may also be caused by conditions that affect hormones, such as tumors; malnutrition; kidney, liver, or thyroid disease; or treatment with certain drugs. It can occur at any age.