Gynaecomastia

May be unilateral or bilateral, painful, or asymptomatic. Male breast enlargement is benign in 99% of cases.

Results from relative oestrogen excess or relative testosterone deficiency resulting in a high oestrogen-to-testosterone ratio.

Physiological gynaecomastia occurs in the newborn period, during puberty, and with ageing and obesity.

Many drugs, environmental exposures, illnesses, and some genetic conditions increase the risk for gynaecomastia.

Most cases require no specific treatment. Therapies for persistent pain or embarrassment include anti-oestrogen therapy such as tamoxifen, androgens, or surgery (liposuction or mammoplasty).

Gynaecomastia is the benign enlargement of the male breast with firm tissue extending concentrically beyond the nipple. Histologically, gynaecomastia is the benign proliferation of breast ducts and duct epithelial hyperplasia accompanied by varying amounts of inflammation, oedema, stroma, and fibrosis. Male breast enlargement entirely due to adipose tissue is called pseudo-gynaecomastia.[Figure caption and citation for the preceding image starts]: Histology: gynaecomastia; clusters of ducts, halos of oedema, fibrous background; 5X magnificationFrom the collection of Catherine B. Niewoehner, MD [Citation ends].