P295 Optical pathway glioma and neurofibromatosis type 1

Background Neurofibromatosis Type 1 (NF1), a autosomal dominant disorder, which mainly involves Skin and nervous system: 15% of children with NF1 develops optic pathway gliomas (OPG), typically Astrocytomas pilocytic low grade, usually in the first decade of life. In one third of cases OPG occur with proptosis, visual impairment, early puberty or other disorders of hypothalamus-pituitary axis. According to current guidelines, children with NF1 should be screened frequently for visual examination and in case of visual impairment, brain MRI with the orbits analysis should performed. The current SIOP-LGG 2004 recommendations, in all cases of no-symptomatic, no-evolving glioma, provide clinical observation with close monitoring; chemotherapy is indicated only in presence of clinical signs and symptoms, or neuroimaging of progression. In the optic nerve tumours, surgery is reserved for patients with blindness, severe proptosis; chiasmatic tumours need surgery in case of exophytic tumours, with cystic component causing severe hydrocephalus or brain compression. patients and methods This is an observational study of 14 cases of OPG (5 males and 9 females) in patients with NF1, diagnosed from 1999 to 2015 c/o Paediatric Oncology Unit of our Department. We evaluated the clinical and radiological course and response to treatment of OPG. Results OPG were located exclusively to the optic nerves level in 43% of patients; 38% presented hypothalamus-optical-chiasmatic localization and 19% had chiasm or optic tracts involvment. The 57% of patients needed of chemotherapy according to the Protocol for Low Grade Glioma, cause of worsening of visual acuity, exophthalmoses or rapid increase of mass-size. The average age of chemotherapy start was 4.6 years (range 1.9 to 7 years). In only two cases there was marked reduction in the size of glioma, while in other cases the radiological picture was confirmed stationary at the stop-Therapy. Chemotherapy has allowed to stabilise the visual impairment, improving in 50% of cases the visual field. Conclusions Our data, accordingly with literature, confirmed that chemotherapeutic treatment for OPG is still unsatisfactory in most cases.