Thelarche means “the beginning of breast development.” Therefore, if a girl begins
to show breast enlargement at an early age (anywhere from birth to six years), it
is called “premature thelarche.”
Technically, most cases of early breast enlargement are harmless, and do not progress
significantly. They are not the beginning of (continued) breast development. They
also are not usually associated with the development of the other physical signs
of puberty, e.g., acne, pubic hair, periods, or rapid growth. Therefore, a better
term for this condition is infantile, or early, “gynecomastia,” which only signifies
that one or both breasts are enlarged.
Studies of girls with early breast enlargement have not shown elevated blood levels
of estrogen or any other abnormality. Occasionally, an ovarian cyst (or cysts) may
be seen on a pelvic ultrasound, but this condition also may occur in girls without
breast enlargement; therefore, it is not clear if the cyst(s) are secreting enough
estrogen to cause the breast enlargement. Some physicians believe that the girls
are just temporarily more sensitive to their normal blood levels of estrogen.
There is not one identifiable group of girls who develops early breast enlargement.
However, it is a concern if a male infant or a young boy shows breast enlargement.
Premature thelarche is not a disease; instead, it is a normal finding in some young
girls or female infants. If there are other signs of puberty, then a physician should
evaluate the child for the causes of early puberty.
The common finding is the enlargement of one or both breasts. In simple premature
thelarche, there are no other signs of pubertal development, and the child is growing
at a normal-not an increased-rate.
Most commonly, premature thelarche is diagnosed in a female infant or a girl up
to three years of age. Occasionally, a girl from three to six years of age will
show an enlargement of one or both breasts. However, after age six, the beginning
of breast development is actually the beginning of puberty; however, it is a very
slow form of development. In addition, girls with early breast development usually
do not have early periods.
Typically, the girl has no other signs of puberty, and is growing at a normal, pre-pubertal
growth rate, i.e., about two inches a year. Laboratory studies are not usually helpful,
since they show low (pre-pubertal) concentrations of estrogen or other hormones
that stimulate pubertal development. An x-ray of the hand shows a picture that is
normal for the girl’s age, and not that of an older girl.
Treatment for early breast development is not necessary; however, the physician
and the parents may want to monitor any changes in the girl’s breast size.
Usually, there are no complications associated with early breast development. Since
there is a very small chance that the girl is actually starting puberty, it is recommended
that both the physician and the parents monitor her.
Premature Thelarche cannot be prevented. Parents should be sensitive to their children’s
concerns and encourage communication so as to alleviate anxiety or fears.
Kappy MS, Ganong CS. Advances in the treatment of precocious puberty. Adv Pediatr
About the Author
Dr. Kappy is a professor of pediatrics at the University of Colorado Health Sciences
Center and the Chief of the Pediatric Endocrinology Department at The Children’s
Hospital in Denver, Colorado.
He was a recipient of the Johns Hopkins University Distinguished Alumnus Award in
1996. His research interest include the treatment of precocious puberty and the
effects of growth hormone in growth hormone-deficient individuals.
Copyright 2012 Michael S. Kappy, M.D., Ph.D., All Rights Reserved
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