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Updated: Aug 14, 2026

Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats
Published on: October 16, 2010
Gynecomastia
1Endocrinology Service, Walter Reed Army Medical Center, Washington, DC.
Abstract:
Gynecomastia is a common finding in men and most often is idiopathic in origin or related to normal puberty. Medications are frequent causes of breast enlargement or tenderness, and hypogonadism of any cause, particularly primary hypogonadism, can lead to gynecomastia. Occasionally, the breast enlargement will reflect an underlying neoplasm that produces steroids or hCG. Underlying systemic disorders (liver disease, renal failure, thyrotoxicosis) can also result in gynecomastia. In most cases, the breast enlargement can be explained by an increased effective estrogen/androgen ratio acting at the breast itself. Therapy should be aimed at correcting any reversible causes, especially when related to medications, and treatment of any serious underlying disorders that are discovered, especially tumors. Medical treatment aimed at reducing the effective estrogen/androgen ratio, particularly with anti-estrogens, appears to be of some effectiveness. Careful surgical removal of excessive tissue can be very helpful, particularly in adolescence and young adulthood.
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