Pathophysiology
The causes of common gynecomastia remain uncertain, but are thought to result from an imbalance between the actions of estrogen and androgens at the breast tissue. The imbalance in the estrogen:testosterone ratio results from increased estrogens or estrogenic precursors secondary to excess secretion by the testicles or adrenal glands; decreased androgens due to decreased secretion or increased metabolism by high levels of sex hormone-binding globulin (SHBG) in some cases may also play a role. This mechanism has been the proposed cause of gynecomastia in certain associated conditions such as hyperthyroidism, chronic liver disease, and the use of certain medications such as spironolactone. Breast prominence can result from hypertrophy of breast tissue, chest adipose tissue (fat) and skin, and is typically a combination. Breast prominence due solely to excessive adipose is often termed pseudogynecomastia or sometimes lipomastia.
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