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SingHealth Duke-NUS Breast Centre


Gynaecomastia is the enlargement of male breast tissue. It is common in newborns, at puberty, as well as in older men.

There is growth of the male breast glands and not just the fat. It may occur in one or both breasts and it is a benign condition.


Gynaecomastia can be due to the imbalance of the sex hormones, testosterone and oestrogen.

Oestrogen is a feminine hormone that causes the breast tissue to grow. Men do produce some oestrogen but they usually have more testosterone which prevents the effects of oestrogen.

  • Hormone imbalance in men can cause the breasts to grow.

  • Obesity increases levels of oestrogen and is also a common cause for gynaecomastia.

  • In newborn baby boys, oestrogen can pass through the placenta from the mother, but this is temporary and will disappear in a few weeks after birth.

  • During puberty, hormone levels change and if the amount of testosterone drops, teenage boys can develop gynaecomastia. This usually clears up after their hormone levels stabilise and is uncommon beyond the age of 17 years.

  • As men get older, they produce less testosterone and tend to have more fat and these can lead to excess breast tissue growth.

  • Medications may sometimes cause gynaecomastia due to their side effects on the hormonal pathways.

  • Common examples include:
    • Some heart medications such as spironolactone, verapamil, nifedipine, enalapril, digoxin and amiodarone
    • Antibiotics/antifungals like ketoconazole, isoniazid and metronidazole
    • Chemotherapy drugs like methotrexate and steroids
    • Psychiatric medications like haloperidol, diazepam and tricyclic antidepressants
    • Recreational drugs including alcohol, amphetamines and heroin

  • Rarer conditions include tumours such as pituitary tumours in the brain, testicular tumours, lung, liver and kidney cancers, kidney, liver or thyroid disease or genetic causes such as Klinefelter syndrome.

  • Sometimes the cause is unknown.


This may present as a rubbery or firm mass that starts from underneath the nipple and then spreads outwards over the breast area. There may be discomfort or tenderness. It may occur in one or both breasts.


A careful examination of your history including the use of medications is important in the diagnosis.

Blood tests to exclude the rarer causes may be performed, and investigations may include mammograms and breast ultrasound if is there is a suspicion of and to exclude breast cancer.


In general, treatment is not needed for most cases. If there is an underlying cause, treating the cause will decrease the breast enlargement.

For men with gynaecomastia of unknown cause or have residual gynaecomastia after treatment of the cause, medical or surgical treatment may be considered.

Medical treatment includes drugs such as Clomiphene and Tamoxifen, which oppose the action of oestrogens. Up to 50 to 80 percent of patients have been reported to achieve partial reduction in breast size with these pharmacologic therapies.

Surgery can remove the amount of breast tissue and the various techniques include reduction mammoplasty, subcutaneous mastectomies with or

without liposuction and microdebridement.

In these surgeries, the breast is either partially or totally removed with the preservation of the nipple and overlying skin.

Cancer risk
There is no increased risk of breast cancer development in men with gynaecomastia, but the diagnosis of cancer needs to be excluded in their management.

Where to Seek Treatment

Specialist services available at the SingHealth Duke-NUS Breast Centre located at:

National Cancer Centre Singapore Tel: 6436 8088
Singapore General Hospital Tel: 6321 4377
Changi General Hospital Tel: 6850 3333
Sengkang General Hospital Tel : 6930 6000
KK Women's and Children's Hospital Tel: 6294 4050

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