Gynecomastia is the development of abnormally large breasts in males.

The condition may occur in one or both breasts and begins as a small lump beneath the nipple, which may be tender. The breasts often enlarge unevenly. Gynecomastia during puberty is not uncommon and usually goes away over a period of months.

In newborns, breast development may be associated with milk flow (galactorrhea). This condition usually lasts for a couple of weeks, but in rare cases may last until the child is 2 years old.

The most common cause of gynecomastia is puberty.

Other causes include:

• Chronic liver disease
• Exposure to anabolic steroid hormones
• Exposure to estrogen hormone
• Genetic disorders
• Kidney failure
• Marijuana use
• Side effects of some medications
• Testosterone (male hormone) deficiency

Rare causes include:

• Genetic defects
• Overactive thyroid
• Tumors

Apply cold compresses and use analgesics as your health care provider recommends if swollen breasts are also tender.

Call your health care provider if the breasts have developed abnormally or if there is swelling or pain in one or both breasts.

Note: Gynecomastia in children who have not yet reached puberty should always be checked by a health care provider.

Your health care provider will take a medical history and perform a physical examination.

Medical history questions may include:

• Is one or both breasts involved?
• What is the age and gender of the patient?
• What medications is the person taking?
• How long has gynecomastia been present?
• Is the gynecomastia staying the same, getting better, or getting worse?
• What other symptoms are present?

Testing may not be necessary, but the following tests may be done to rule out certain diseases:

• Blood hormone level tests
• Breast ultrasound
• Liver and kidney function studies
• Mammogram

Intervention:

If an underlying condition is found, it is treated. Gynecomastia during puberty usually goes away on its own; however, persistent, extreme, or uneven breast enlargement may be embarrassing for an adolescent boy. Breast reduction surgery may be recommended.

After seeing your health care provider:

If your health care provider made a diagnosis related to gynecomastia, you may want to note that diagnosis in your personal medical record.