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.
Professor of Medicine
University of Minnesota
CBN is an author of a number of references cited in this monograph.
Professor of Pediatrics
Rumsey Chair of Pediatric Endocrinology
University of California
DS declares that he has no competing interests.
Professor of Medicine and Head of Endocrinology
Stony Brook University
HC is an author of a reference cited in this monograph.
Professor and Chairman
Department of Medicine
Cedars-Sinai Medical Center
GB declares that he has no competing interests.
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