Study Title:

Gynecomastia - Male Reproductive Endocrinology and Related Disorders

Study Abstract

Gynecomastia is hypertrophy of breast glandular tissue in males. It must be differentiated from pseudogynecomastia, which is increased breast fat, but no enlargement of breast glandular tissue.

Pathophysiology
During infancy and puberty, enlargement of the male breast is normal (physiologic gynecomastia). Enlargement is usually transient, bilateral, smooth, firm, and symmetrically distributed under the areola; breasts may be tender. Physiologic gynecomastia that develops during puberty usually resolves within about 6 mo to 2 yr. Similar changes may occur during old age and may be unilateral or bilateral. Most of the enlargement is due to proliferation of stroma, not of breast ducts. The mechanism is usually a decrease in androgen effect or an increase in estrogen effect (eg, decrease in androgen production, increase in estrogen production, androgen blockade, displacement of estrogen from sex-hormone binding globulin, androgen receptor defects).

Study Information

Irvin H. Hirsch, MD
Gynecomastia - Male Reproductive Endocrinology and Related Disorders

2016 June

Full Study

http://www.merckmanuals.com/professional/genitourinary-disorders/male-reproductive-endocrinology-and-related-disorders/gynecomas