Precocious Puberty in Girls and the Risk of a Central Nervous System Abnormality: The Elusive Search for Diagnostic Certainty

The classic approach to the work-up of central precocious puberty (CPP) has been to recommend a brain imaging study to exclude an anatomic cause for the early onset of puberty, such as a tumor (most commonly a glioma or an astrocytoma), a hamartoma, or a subarachnoid cyst. Given the relative infrequency of CPP in boys and the relatively high reported incidence of abnormal findings,¹ few would argue with ordering a magnetic resonance imaging (MRI) or a computed tomography scan as part of the evaluation for boys. The situation for early-maturing girls is much less clear. Many authors have advocated brain imaging for all girls meeting the criteria for CPP (age of onset <8 years plus evidence of activation of the hypothalamic-pituitary-gonadal axis), although it was recognized that in the majority of cases (80% to >90%, depending on the study), the study would be normal.² Others have recommended imaging in girls with CPP mainly “if there is a hint of intracranial pathology”.³ In practice, each clinician develops his or her own criteria for deciding when to order an MRI, so there is no consensus as to whether a healthy 6- to 8-year-old girl with breast development but no central nervous system (CNS) signs or symptoms needs brain imaging. In the past 2 decades, as clinicians have seen an increasing number of girls with onset of breast development before 8 years of age, this question takes on a greater urgency. The data of Herman-Giddens and the Pediatric Research in Office Settings (PROS) group, collected in 1992–1993 and published in 1997, indicate that by 8 years of age, close to 25% of black and 8% of white girls will have some breast tissue.⁴ The data from National Health and Nutrition Examination Survey III, collected between 1988 and 1994, give …