What is the pathogenesis of gynecomastia?

Updated: Mar 22, 2018
  • Author: George Ansstas, MD; Chief Editor: George T Griffing, MD  more...
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Gynecomastia results from an altered estrogen-androgen balance, in favor of estrogen, or from increased breast sensitivity to a normal circulating estrogen level. [6] The imbalance is between the stimulatory effect of estrogen and the inhibitory effect of androgen. (The normal production ratio of testosterone to estrogen is approximately 100:1; the normal ratio of testosterone to estrogen in the circulation is approximately 300:1.)

Estrogens induce ductal epithelial hyperplasia, [7] ductal elongation and branching, proliferation of the periductal fibroblasts, and an increase in vascularity. The histologic picture is similar in male and female breast tissue after exposure to estrogen. [8]

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