Diagnostic Considerations
In the evaluation of a child with GnRH-independent precocious puberty (PPP), distinguishing between the common variants of premature thelarche and premature pubarche is important.
Premature thelarche (PT) is the appearance of breast development in young girls in the absence of other signs of precocious puberty (eg, growth acceleration, changes in uterine size and vaginal mucosa). Premature thelarche is typically seen in girls aged 3 years or younger. Breast tissue normally seen in the newborn period due to maternal estrogens can persist for a year or more in some infants. The keys to making this diagnosis include the following:
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Observing that the child is growing in length along her established percentile channel.
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Noting that the amount of breast tissue increases only minimally over time (or may even decrease).
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Observing a lack of thickening and pigmentation of the nipples and the areola as seen in girls with precocious puberty.
The etiology of this condition is unknown. In some cases, small ovarian cysts that transiently produce estrogens may be responsible. In Puerto Rico, an epidemic of premature thelarche in the 1970s was suspected to have been caused by exposure to estrogens in poultry. Despite a lack of firm evidence, phytoestrogens in soy products and other environmental estrogenlike agents (eg, pesticides, phthalates) may have the potential to cause breast development in young children.
Premature pubarche refers to the early appearance of pubic hair, axillary hair, or both in children without other signs of puberty. An adult-type axillary body odor is the other major clinical finding. Signs of severe androgen excess (eg, clitoral enlargement, growth acceleration, severe acne) should prompt further investigation to exclude a rare virilizing tumor or a variant form of congenital adrenal hyperplasia. The etiology of premature pubarche is an earlier-than-usual increase in the secretion of weak androgens by the adrenal glands (also termed premature adrenarche). Although regulation of adrenal androgen secretion is poorly understood, it is distinct from that of gonadal steroids. Therefore, early appearance of pubic hair may not temporally correlate with appearance of breast development and is generally not a cause for concern.
Differential Diagnoses
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Aromatase excess syndrome
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Choriocarcinoma
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Exposure to exogenous estrogen or androgen
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Feminizing adrenal tumor
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Germ cell tumors
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Luteinizing hormone (LH)-secreting pituitary adenoma
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Syndrome of glucocorticoid resistance
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Virilizing adrenal tumor
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Graph represents the prevalence of breast development at Tanner stage 2 or greater by age and race.
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Graph represents the prevalence of pubic hair at Tanner stage 2 or greater by age and race.
