Male breast enlargement, or gynecomastia, is a fairly common condition in men. The enlargement may be a result certain medication side effects, use of marijuana, liver disorders, or hormone-secreting tumors. However, the majority of cases is attributed to events during development. Up to 33% of boys in puberty will develop enlargement of the breast -- In many, the breast regresses but in some the breast tissue will persist. Another common source of breast enlargement, as in women, is weight gain. Depending on the severity gynecomastia may be addressed by liposuction alone or may require cutting out the excess breast tissue through a small incision.