Gynaecomastia is the presence of palpable breast tissue in a male patient. It results from an increase in the effect of oestrogen relative to the effect of androgen acting on the breast tissue. In overweight males there may appear
to be extra breast tissue but this is more often lipomastia (fat deposition).
Histological changes of gynaecomastia are found in 40% of autopsy specimens – it is very common but can indicate underlying pathology. Digoxin, spironolactone, cimetidine and metronidazole can all cause gynaecomastia, as can the use of recreational steroids.