Gynaecomastia is a medical term for enlarged breast(s). It is usually used in reference to men who have abnormal breast development as a result of hormonal imbalances or drug side effects. It is also a condition associated with occupational exposure to oestrogen dust, feeding of refugees, and ingestion of tainted food.
The most common reason is the onset of puberty in teenage boys, when there may be a temporary hormone imbalance. Male breasts sometimes enlarge in old age, with an increase in weight, and with oestrogen hormone treatment in men wanting to change sex. It may also be a symptom of a significant underlying disease including cirrhosis of the liver, cancer in the adrenal glands, overactivity or cancer of the thyroid gland, an uncommon form of lung cancer, a tumour in the testicles or a genetic condition called Klinefelter syndrome in which there is an extra sex chromosome.