How many cases of true precocious puberty in girls are idiopathic?

Fifteen girls with true precocious puberty were examined by computerized tomography. In seven hypothalamic hamartomas were suspected. A pneumoencephalogram was performed in six cases (one patient refused), with the following results. In five, the radiological features were highly suggestive of tuber cinereum hamartoma. All of our patients with pubertal signs appearing before the age of 2 years and 80% of the girls with early menstruation were in the group with suspected hamartoma. The luteinizing hormone and follicle-stimulating hormone levels of these five girls were significantly higher than those observed in the other girls with idiopathic precocious puberty. We conclude that there is a high frequency of small hypothalamic masses (suspected hamartoma) in girls with true precocious puberty (33% of the patients in our group), that it is important to confirm the presence of the mass with pneumoencephalography, and that surgery for diagnostic and therapeutic purposes should be carefully considered, given the absence of any neurologic symptoms for a long time after the appearance of the first pubertal signs.