NS-27. INFANTS WITH CENTRAL NERVOUS SYSTEM TUMOURS A FIVE-YEAR RETROSPECTIVE REVIEW Soumya Mukherjee, Ramakrishna Bethanabatla, Gnanamurthy Sivakumar, Atul Tyagi, PaulChumas, and John Goodden; Leeds General Infirmary,Leeds, UK INTRODUCTION: Central nervous system(CNS) tumours in children , 2 years are rare. We have studied tumour types, treatment and outcomes in children , 2 years treated at a single institution. METHOD: Retrospective analysis was undertaken of consecutive children under 2 years old with CNS tumours treated at a single institution between January 2011 to December 2015. Data collected included demographics, tumour location, histology, treatment details, and outcome. RESULTS: 32 patients were treated with a mean age of 10.8 months (range, 3.1 to 24 months) and male-to-female ratio of 1:1. 14 (44%) had posterior fossa tumours (PFT) and 18 (56%) supratentorial tumours (STT) with a rate of hydrocephalus of 93% (13/14) and 44% (8/18), respectively (p , 0.05). The rate of hydrocephalus across the cohort was 65%. Commonest histologies amongst the PFT group were ependymoma, pilocytic astrocytoma, and medulloblastoma, whilst amongst the STT group were ependymoma, pilomyxoid astrocytoma, primitive neuroectodermal tumour and choroid plexus papilloma. Other pathological types included atypical teratoid rhabdoid tumour (ATRT) and ependymoblastoma. Operative approaches included supratentorial (38%: total 25%, subtotal 13%); midline posterior fossa (25%: total 16%, subtotal 9%), retrosigmoid (16%), endoscopic biopsy +/resection (16%) and open biopsy (12.5%). CSF diversion surgery (VP shunt, EVD, ETV) was performed in 35% of patients. Overall complication rate was 9%. Median survival was 40 months and all-cause 5-year mortality was 23% (8/35). CONCLUSION: Our series demonstrates varied tumour diagnoses in infants , 2 years and their surgical challenges. Despite these good outcomes can be achieved. Neuro-Oncology 18:iii127–iii134, 2016. doi:10.1093/neuonc/now078.27 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.