Gynecomastia (Male Breast Enlargement)

What causes gynecomastia

Breast tissue grows when estrogen effects outweigh androgen (testosterone) effects. This happens when estrogen rises, testosterone falls, or the tissue becomes more sensitive.

Physiological gynecomastia

• Newborns: from the mother's estrogen. Resolves within weeks.
• Puberty: affects a large share of boys, typically starting around 13 to 14, from temporary hormone imbalance. Most cases resolve within 6 months to 2 years.
• Older age: testosterone falls and body fat, which converts androgens to estrogen, increases.

Medicines and substances

• spironolactone
• anti-androgens and treatments for prostate cancer (bicalutamide, GnRH agonists)
• 5-alpha reductase inhibitors (finasteride, dutasteride)
• some antipsychotics and antidepressants
• some heart medicines (digoxin, some calcium channel blockers)
• some HIV medicines
• cimetidine, ketoconazole, metronidazole
• anabolic steroids and testosterone (including during or after a cycle)
• alcohol, cannabis, opioids
• estrogen-containing products, lavender and tea tree oils (reported in boys)

Medical conditions

• low testosterone or hypogonadism, including Klinefelter syndrome
• cirrhosis and liver disease
• chronic kidney disease and dialysis
• hyperthyroidism
• obesity
• refeeding after malnutrition
• tumors: testicular tumors (Leydig cell, germ cell), adrenal tumors, and tumors producing hCG

Often no specific cause is found (idiopathic).

Symptoms

• a firm or rubbery disc of tissue directly under the nipple and areola
• one or both sides, sometimes uneven
• tenderness or sensitivity, especially in early stages
• swelling of the areola

Gynecomastia vs fat vs cancer

Male breast cancer is rare, but men with any of the warning signs should be checked promptly.

Diagnosis

• history: onset, medicines, supplements, substance use, liver, kidney and thyroid symptoms, sexual function
• examination: breasts, testicles, signs of liver disease and thyroid disease
• blood tests for adult or unusual cases: testosterone, estradiol, LH, FSH, prolactin, hCG, thyroid, liver and kidney function
• testicular ultrasound if hormones suggest a tumor or a lump is felt
• mammogram or breast ultrasound if cancer is a concern

Typical pubertal gynecomastia with normal examination usually needs no tests.

Treatment

Observation

Most pubertal gynecomastia resolves on its own. Reassurance and follow-up are appropriate.

Treat the cause

• stop or switch causative medicines where possible
• stop anabolic steroids, cannabis and alcohol
• treat hypogonadism, thyroid disease, liver or kidney disease

Medicines

• tamoxifen, an estrogen receptor blocker, can reduce painful gynecomastia of recent onset, ideally within the first 6 to 12 months, before tissue becomes fibrous
• used preventively in some men receiving anti-androgen therapy for prostate cancer, sometimes alongside low-dose breast radiotherapy

Surgery

For long-standing (fibrous) gynecomastia that causes distress or discomfort:

• liposuction for fatty components
• subcutaneous mastectomy to remove glandular tissue through a small incision around the areola

Surgery is usually delayed in teenagers until breast development has stabilized.

Emotional impact

Gynecomastia can cause embarrassment, avoidance of sport or swimming, and low self-esteem, especially in teenagers. Talking about it with a doctor and, if needed, a counselor helps.

Frequently asked questions

What causes gynecomastia?

Gynecomastia is caused by an imbalance between estrogen and testosterone. It is normal in puberty and older age, and can also be caused by medicines, anabolic steroids, alcohol, cannabis, obesity, liver or kidney disease, thyroid problems, low testosterone and, rarely, tumors.

Does gynecomastia go away on its own?

Pubertal gynecomastia usually goes away within 6 months to 2 years. Drug-related gynecomastia often improves after stopping the medicine, if caught early. Long-standing gynecomastia becomes fibrous and may need surgery.

How do I know if it is gynecomastia or fat?

Gynecomastia feels like a firm, rubbery disc directly behind the nipple. Fat feels soft with no distinct disc. A doctor can tell the difference on examination, and ultrasound can help if unsure.

Can gynecomastia be a sign of cancer?

Rarely. A hard, off-center lump, skin dimpling, nipple changes or bloody discharge could indicate male breast cancer. Gynecomastia with a testicular lump may point to a testicular tumor. These need prompt assessment.

Can exercise get rid of gynecomastia?

Exercise and weight loss reduce fat on the chest but do not remove glandular breast tissue. True gynecomastia may need time, treatment of the cause, medicine or surgery.