Summary

  • May be unilateral or bilateral, painful, or asymptomatic. Male breast enlargement is benign in 99% of cases.
  • Results from relative estrogen excess or relative testosterone deficiency resulting in a high estrogen-to-testosterone ratio.
  • Physiologic gynecomastia occurs in the newborn period, during puberty, and with aging and obesity.
  • Many drugs, environmental exposures, illnesses, and some genetic conditions increase the risk for gynecomastia.
  • Most cases require no specific treatment. Therapies for persistent pain or embarrassment include anti-estrogen therapy such as tamoxifen, androgens, or surgery (liposuction or mammoplasty).

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