A 4-year-old Caucasian girl presents to her pediatrician because of early development of breast buds, pubic hair, and body odor. On exam, the girl is noted to have Tanner stage 3 breast buds and pubic hair. She is also noted to have clitoromegaly (Figure 200-1). The pediatrician refers the girl to a pediatric endocrinologist, who orders a bone age, estradiol levels, and an MRI of the brain. The girl is found to have an advanced bone age of 7 years, and levels of estradiol consistent with her stage of sexual development. An MRI of the brain is normal. She is diagnosed with idiopathic central precocious puberty. The options for management are discussed with the family.
Pubic hair development and clitoromegaly in a 4-year-old girl with central idiopathic precocious puberty. (Used with permission from Elumalai Appachi, MD.)
The age at which puberty begins in normal children varies among the different ethnic groups. Early, or precocious puberty, is defined as the onset of sexual development occurring before the age of 7 years in Caucasian girls, 6 years in African American girls, and 9 years for all boys. Central precocious puberty refers to gonadotropin-releasing hormone (GnRH)-dependent activation from the hypothalamic-pituitary-gonadal axis leading to secondary sexual characteristics. Peripheral precocious puberty refers to GnRH-independent activation.
The incidence is estimated to be 15 to 30 per 100,000 girls and is 1- to 15-fold less common on boys.1,2
Idiopathic precocious puberty is more common in girls than boys.
African American girls develop secondary sexual characteristics at an earlier age than Caucasian girls. Thus, age of evaluation of precocious puberty in girls depends on ethnicity and race.
Boys mature at comparable ages regardless of ethnicity and race.
Age of onset of precocious puberty varies depending on the etiology; it can present as early as the first month of life.
Etiology and Pathophysiology
Central or GnRH-dependent precocious puberty may be idiopathic or may be caused by a central nervous system (CNS) abnormality.3,4
Precocious puberty is idiopathic in more than 90 percent of girls. This diagnosis is one of exclusion, in that no clinical, biochemical, or radiologic abnormalities are present other than those of precocious puberty.
Boys with precocious puberty have an idiopathic cause much less commonly than girls; CNS abnormalities are found in 25 to 75 percent of boys with precocious puberty.
The most common CNS abnormality causing precocious puberty is a hypothalamic hamartoma. This is a GnRH-producing nonmalignant congenital mass that causes pulsatile secretion of gonadotropins leading to stimulation of the gonads during childhood.5
Other structural CNS abnormalities include tumors such as pinealoma, astrocytoma, ...
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