Neurofibromatosis type 1 and precocious puberty

Since neurofibromatosis type 1 (NF1) is a well known cause of precocious pu berty (PP), we reviewed 412 NF1 pediatric patients to evaluate the prevalen ce of PP, the association with optic pathway tumors (OPT), and other clinic al, auxological and hormonal data. Thirty-one of 412 patients had OPT (7.5% ), 10/412 PP (2.4%), and in seven of these PP was associated with OPT (7/31 , 22.6%), OPT in patients with PP involved the chiasm in four patients, and the optic nerves alone in three patients. The age at the onset of puberty (or better at diagnosis) ranged from 5.2 to 7.5 yr in girls (n=6) and from 7.9 to 8.9 yr in boys (n=4), LHRH agonist therapy was used in only three ch ildren because in the others the predicted height at diagnosis was good, tr eatment was refused or the patients were referred to us too late. The three treated patients attained a final height within the familial range. In the untreated patients the progression of puberty was not too rapid and final height was slightly below the genetic target in four patients; however, thr ee patients had a final height markedly below the familial range. In conclu sion, the prevalence of PP is increased in children with NF1, and frequentl y but not exclusively is associated with OPT. Moreover, sexual precocity do es not seem to be necessarily bound to chiasmatic OPT. Treatment seems to b e useful in the children with younger age at the onset of puberty or with a progressive decline in predicted final height.