Gynecomastia can occur in persons of any age. During adolescence, males develop firmness around the breast as the breast bud enlarges due to the hormonal fluxes of puberty. The subareolar firmness which normally develops regresses with time. Breast tissue is typically present on a microscopic level in male patients; a small amount of breast tissue is normal. The visible appearance of breast tissue in a male is abnormal.
The definition of clinically significant gynecomastia is subject to interpretation by any author; therefore, reports in the literature are often confusing, as the reader is forced to compare apples to oranges when examining different studies. Nydick et al reported 65% of boys "may have the problem" but cautioned that it typically resolves.2 Webster noted the incidence of gynecomastia to be around 8% in a series of naval patients,3 while Williams noted that 40% of men examined in his series of autopsies had gynecomastia to some degree.4 Approximately 40% of healthy men and up to 70% of hospitalized men have palpable if not visible breast tissue. The incidence of some degree of palpable breast tissue in males increases to more than 60% in those in the seventh decade of life in one series.