GH EXCESS IN CHILDREN WITH OPG AND NF1: A SINGLE INSTITUTION EXPERIENCE

Optic pathway gliomas (OPGs) are low-grade tumors often arising in the context of Neurofibromatosis 1 (NF1). NF1 can be associated with a dysre- gulation of Growth Hormone (GH) secretion: whereas a deficiency is well known, the occurrence of GH excess is exceedingly rare and mostly involves children with OPGs. We describe GH excess in a cohort of patients referred to our institution for OPG. Children diagnosed with OPG were evaluated for height, height-velocity and pubertal status. When height velocity was .2 SDS, FT4, TSH, prolactin basal levels, IGF-1, GH levels after oral glucose tolerance tests (OGTT) and bone age were assessed. If precocious puberty was evident, LH and sex steroid hormone levels were tested. Children with a confirmed GH excess (lack of GH suppressibility to ,1.0 ng/mL during OGTT) were treated with GH inhibitor lanreotide. From January to December 2013, 37 children (median age 110 months; F/M 19/18) were screened. Thirty-four patients (92%) had NF1, seven of which (19%) showed a pathologic GH secretion (median IGF1 390 ng/ml). Median height was 2.96 SDS and all children showed normal levels of FT4, TSH, prolactin. One child was already being treated for precocious puberty with complete clinical and biochemical control and 3 were receiving chemother- apy according to SIOP LGG 2004 protocol. Lanreotide was started in 3 chil- dren obtaining the normalization of IGF-1 levels with no major adverse events. Disease assessments after 6-12 months showed clinical and radio- logical stability in all the patients; notably, one of them had previously shown persistent progression despite chemotherapy. Our pilot study suggests that pathologic GH secretion in children with OPG and NF1 could be more frequent than previously reported. Treatment with lanreotide was well toler- ated and effective at reducing GH secretion, an effect that might improve tumor control. Larger cohort and longer follow-up are required to draw firm conclusions.