breast enlargement with increased breast gland tissue in men is called gynecomastia. In only a few men, the breasts remain enlarged at the end of the teen years. This is not usually because there is anything wrong with the male hormones, but because the enlarged breast tissue has remained hypersensitive to the tiny normal amounts of oestrogen, or else is not responsive to the shutting down effect of testosterone. 19, 2007 -- gynecomastia, the enlargement of breast tissue in men, can be an embarrassing condition, but it is surprisingly common and usually benign. testosterone in the male body usually prevents the breast tissue from expanding. However, some males develop enlarged breasts due to hormonal changes or fluctuations. Men may experience enlarged breasts as a result of hormonal changes associated with aging. When a man or boy has enlarged breasts, he is said to have gynecomastia. This condition occurs when estrogen and testosterone become imbalanced in the male body. The condition is frequently seen in newborn male babies and boys that are going through the natural changes of puberty.