All Ages... Gynecomastia comes from the greek meaning "gyne" meaning woman and "mastos" meaning breasts. it refers to abnormal development of large mammary glands in males. Although there may be many “causes”, most cases are idiopathic (no specific cause). The use of certain medications, drugs, organ dysfunction (kidney or liver), hormonal imbalances etc. May also be causative.
Breasts in men . Gynecomastia is the presence of glandular (potentially milk-producing) tissue in the male breast. It can happen during normal puberty, but can also be caused by some meds like digoxin and cimetidine, by marijuana use, low testosterone, use of excess testosterone or other body building steroids, and certain tumors.
Breast Swelling. Gynecomastia is enlargement of the breast tissue. Men get this when the breast tissue (yes men have breast tissue) gets stimulated from some source to grow. This can be medications, hormones, etc.