Breast Enlargement in Adolescent Boys

Breast Enlargement in Adolescent Boys

Male breast enlargement (gynecomastia) is a normal condition that occurs during puberty in more than 60% of boys.

Prevalence

Aproximately 20% of 10½-year-old boys and more than 60% of 14-year-old boys experience gynecomastia (breast enlargement). In addition to swollen breasts, the area around the nipples may feel tender or lumpy. The appearance of gynecomastia can be distressing because it appears at a time when boys are concerned about their sexual identity and development. In 70% of boys, however, it disappears within a year; in less than 8% does it persist for more than two years. Gynecomastia does not indicate disease in most boys, and there is no link between gynecomastia and breast cancer in males.

Cause

It is not clear what causes gynecomastia, but most likely it is related to normal hormonal changes that occur during puberty. Levels of both male and female hormones increase in boys and girls during puberty. As the levels of these hormones adjust, some female characteristics (such as gynecomastia) may appear in boys, and some male characteristics (such as increased body hair) may appear in girls.

In some cases, gynecomastia is related to medication. If an adolescent boy with gynecomastia is taking medication, or if gynecomastia appears before puberty begins or after it has been completed, a doctor should be consulted.

In some relatively rare instances, gynecomastia may be the result of a chromosomal abnormality, where the male has one or more extra X chromosomes. This condition is known as Klinefelter's syndrome.

Books

McCoy, Kathy, and Charles Wibbelsman. The New Teenage Body Book. New York: The Body Press (Putnam), 1992.

—Gail B. Slap, M.D.
University of Pennsylvania School of Medicine