Gynecomastia.

Gynecomastia may be physiologic, familial, pathologic, drug-induced or, in many cases, of unknown etiology. Breast enlargement is usually unilateral and asymptomatic. Mechanisms of gynecomastia involve increased estrogen stimulation, decreased testosterone levels or a decreased androgen/estrogen ratio. Hyperprolactinemia is not a cause. Treatment of gynecomastia should be directed at the underlying cause when one can be identified. Most cases are benign and can be managed by explanation, reassurance and observation.