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Clinical features, diagnosis, and evaluation of gynecomastia in adults

Glenn D Braunstein, MD
Bradley D Anawalt, MD
Section Editor
Alvin M Matsumoto, MD
Deputy Editor
Kathryn A Martin, MD


Gynecomastia, a benign proliferation of the glandular tissue of the male breast, is caused by an increase in the ratio of estrogen to androgen activity. It may be unilateral or bilateral and is diagnosed on exam as a palpable mass of tissue at least 0.5 cm in diameter (usually underlying the nipple).

The causes and evaluation of gynecomastia will be reviewed here. Epidemiology, pathogenesis, and management of gynecomastia and an overview of gynecomastia in children and adolescents are discussed separately. (See "Epidemiology, pathophysiology, and causes of gynecomastia" and "Management of gynecomastia" and "Breast masses in children and adolescents".)


Gynecomastia is defined histologically as a benign proliferation of the glandular tissue of the male breast and clinically by the presence of a rubbery or firm mass extending concentrically from the nipple. Gynecomastia differs from female breast development in that there is no progesterone-induced terminal alveolar development. (See "Breast development and morphology".)

Physiologic gynecomastia, which resolves spontaneously in most cases, has a trimodal distribution, occurring in neonatal, pubertal, and older males. The estimated prevalence of asymptomatic gynecomastia in these three age groups is 60 to 90 percent in neonates, 50 to 60 percent in adolescents, and 35 to 65 percent in men ages 50 to 69 years [1]. (See "Gynecomastia in children and adolescents", section on 'Definition and characteristic features'.)

Pseudogynecomastia, which is often seen in obese men, refers to fat deposition without glandular proliferation. Gynecomastia must be differentiated from breast carcinoma, which is far less common. (See "Breast cancer in men", section on 'Clinical presentation' and 'Further evaluation to rule out breast cancer' below.)

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Literature review current through: Nov 2017. | This topic last updated: Feb 10, 2017.
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