this is called gynecomastia, the benign enlargement of the male breast. if it has been present your whole life it is called physiologic gynecomastia and no work up is needed. However there are causes of secondary enlargement that need to be evaluated. If the breast developed over time but definitely were not always present, there could be a problem internally. Unfortunately there is not much that can be done for physiologic gynecomastia other than plastic surgical procedures to reduce the tissue present.
I hope this is helpful to you - best wishes
DrStephanie