What is Gynecomastia?

By Dr Ananya Mandal, MD

Gynecomastia is a condition where men develop abnormally large breasts. The enlargement is not of fat but breast tissues.

Anatomy of breasts

Breasts in men and women are mainly composed of fat tissues, ducts or tubes, glands and muscles with a nipple and areola at the forefront.

Breast tissues refer to the glands and muscles tissues. In men there are very little glandular tissues.

When gynecomastia occurs there is growth of the breast tissues and not merely the fat around the tissues. (1, 2, 3)

Symptoms of Gynecomastia

Gynecomastia may affect one or both breasts and may often start behind the nipple as a painful swelling.

The enlargement may be uniform but more often than not is uneven and disproportionate.

Normally male hormones or androgens are responsible for the male features like deep voice, muscle growth, hair baldness pattern, facial and body hair patterns etc.

Female hormones like Estrogen is responsible for female characteristics like hair patterns, breast development etc.

In men the androgens are converted to estrogens in very miniscule amounts. Thus they have a predominance of androgens in their blood.

Causes of Gynecomastia

There are multiple causes of Gynecomastia. Some amount of normal or physiological Gynecomastia is seen in around 60% of boys during puberty. This usually goes away on its own over a few months time.

In 70% of boys this breast bud goes away in a year and in 90% it goes away in two years.

Newborn boys also may develop breast engorgement or enlargement even with milk flow. This is called galactorrhea. This may last a week or two after birth or rarely longer.

This occurs due to the influence of maternal female hormones on the baby boy when he is still within the uterus.

With age and obesity some people normally develop breast enlargement. This may not always be actual Gynecomastia.

Other causes may be:

Some genetic conditions that lead to under development of testes in boys like Klinefelter’s syndrome also causes lack of testosterone leading to Gynecomastia. (3, 4)

Gynecosmastia and breast cancer

Sometimes breast enlargement in men may be an underlying symptom of breast cancer.

Although this is rare in men, Gynecomastia needs adequate work up to exclude cancer.

Breast cancer should be suspected if there is a firm or hard breast lump especially on one side, sore skin over the lump or blood and other discharge from the nipple.

Is Gynecomastia harmful?

Gynecomastia on its own may not be harmful. In pubertal and adolescent boys it may even go away by itself.

However, it may be embarrassing and affect the individual psychologically.

Sometimes some individuals may choose therapy to reduce or treat Gynecomastia. These include hormonal therapies that block the female hormones or cosmetic breast reduction surgeries.

In growing boys this could help prevent psychological issues, improve self esteem and prevent bullying and other problems at school.

Edited by April Cashin-Garbutt, BA Hons (Cantab)

Further Reading

Gynecomastia Causes
Gynecomastia Symptoms
Gynecomastia Diagnosis
Gynecomastia Treatments


  1. http://www.nlm.nih.gov/medlineplus/ency/article/003165.htm
  2. http://www.mayoclinic.com/health/gynecomastia/DS00850
  3. http://men.webmd.com/tc/gynecomastia-topic-overview
  4. http://www.merckmanuals.com/professional/genitourinary_disorders/male_reproductive_endocrinology_and_related_disorders/gynecomastia.html
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