Gynecomastia
Gynecomastia is enlargement of male breast tissue, and it is common -- up to two-thirds of adult men have some palpable tissue, and about 70% of boys develop a pubertal version that resolves on its own. Management follows the Italian Society of Andrology and Sexual Medicine (SIAMS) guideline, the strongest dedicated guideline currently available.
Symptoms
A firm, sometimes tender disc of tissue directly under the nipple, distinct from the soft, diffuse fat of simple weight gain (pseudogynecomastia).
Causes and risk
Medications (spironolactone, certain prostate cancer drugs, cimetidine, anabolic steroids), liver disease, low testosterone, hyperthyroidism, and marijuana or alcohol use are the most common identifiable causes; a substantial share is idiopathic.
How it is evaluated
For recent-onset or symptomatic cases, labs check testosterone, LH, FSH, estradiol, hCG, prolactin, and thyroid function. Breast imaging follows age-based thresholds (ultrasound under 25, mammography 25 and older) when cancer is a concern.
Treatment
Physiologic or recent-onset cases are often simply observed. When a cause is found, treating it is the priority. Tamoxifen (off-label) works best in the early, proliferative window (under about 2 years); testosterone is only appropriate for proven, confirmed hypogonadism. Surgery is for fibrotic or persistently distressing tissue.
When to seek care
A hard, eccentric, unilateral mass, nipple retraction or discharge, skin dimpling, rapid growth, or a swollen lymph node under the arm are red flags for male breast cancer and need prompt evaluation, not routine observation.