overdevelopment of the male breast. The glandular tissue of the breast swells,
usually in response to an excess of the female hormone
estrogen or a lack of
testosterone, a male hormone. It occurs in babies,
teen boys, and older men.
What causes gynecomastia?
In newborns, gynecomastia
is caused by estrogen from the mother. Breast buds are common in baby boys. Breast buds tend to
go away gradually by 6 months of age, but they can last longer in some babies.
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In preteen boys,
breast buds are common during puberty. They may
last up to 2 years, but they tend to go away within the first year. In a few cases, it has been linked to regular use of lavender
or tea tree oil in certain lotions or oils.1
Gynecomastia can also be caused by an estrogen-producing tumor.
In teen boys, gynecomastia occurs in more than 60% of boys during early puberty to middle
puberty. This resolves in 70% of boys within 1 year and 90% of boys in 2
years. It is caused by the
hormonal changes of
When gynecomastia occurs in adult males, it is usually caused by another
condition, such as liver or lung cancer,
cirrhosis of the liver, overactive thyroid, or by
hormone problems, such as cancer of the
adrenal glands, or testicles. Alcohol, marijuana,
methamphetamine, and heroin use also may cause gynecomastia.
of certain medicines may also cause gynecomastia, including:
containing tea tree oil or lavender oil.1
What are the symptoms?
In addition to having
enlarged breasts, men or boys with gynecomastia may notice their breasts feel
rubbery or firm. Boys may have a breast bud on one or both sides about the size
of a nickel or quarter. Breast buds are common in adolescent boys
during puberty. They may last up to 2 years, but they tend to go away within
the first year.
How is gynecomastia diagnosed?
usually be diagnosed from a physical examination and medical history. In most
cases, tests are not necessary. But if the breast lump is unusually large,
one-sided, tender, or hard and fixed, a biopsy may be done to rule out other
Any man with a one-sided breast lump should let his
doctor know if he has close relatives who have had breast cancer (mother,
sister, or daughter). If there is any concern about cancer, a lump can be
checked with a biopsy or surgery.
How is it treated?
Gynecomastia in babies and teens
normally does not require treatment and will usually resolve on its own. If
caused by medicine or disease, stopping the medicine or treating the disease
will often cure the gynecomastia. If caused by a lack of testosterone and
increase in estrogen, hormonal treatment may be prescribed.
Henley DV, et al. (2007). Prepubertal gynecomastia
linked to lavender and tea tree oils. New England Journal of Medicine, 356(5): 479-485.
Primary Medical Reviewer
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical Reviewer
H. Michael O'Connor, MD - Emergency Medicine
September 9, 2011
WebMD Medical Reference from Healthwise
September 09, 2011
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