Gynecomastia is the name given to abnormal but benign growth in the amount of breast tissue due to the imbalance of estrogen and testosterone hormones in men. Gynecomastia may affect one breast in some cases and both breasts in some cases. Both breasts may be affected irregularly and reach different sizes.
Newborns, adolescents, and older men can develop gynecomastia as a result of normal changes in hormone levels. However, there are other reasons for the development of gynecomastia.