PEDT-02 DIAGNOSIS, TREATMENT AND CLINICAL OUTCOME OF ATYPICAL BRAINSTEM TUMOUR IN CHILDHOOD

BACKGROUND: Brainstem tumours account for 10–15% of brain tumors in childhood. Diffuse intrinsic pontine glioma (DIPG) accounts for 60–80% of them and are diagnosed based on clinical findings and radiologic features. All the rest of tumours excluding DIPG are very rare, heterogeneous group of tumours including low-grade glioma and malignant embryonal tumors. It is often difficult to diagnose and decide treatment strategy for their rarity. METHODS: To present our experience with atypical brainstem tumours, a retrospective chart review was conducted to identify eligible cases treated over a ten-year period. All tumors involving brainstem, felt not to be DIPGs for absence of clinical/neuroimaging features were included. Demographic information, pathological findings, neuroimaging characteristics, surgical and nonsurgical management plans, and survival data were collected for analysis. RESULTS: Between April 2007 and March 2017, 16 patients (14 initial and 2 recurrent) aged from 3 to 20 years were identified. 14 of them were symptomatic and 4 of them were asymptomatic at reference. Of 10 symptomatic cases, 10 were biopsied and pathological diagnosis was low-grade glioma in 8, glioblastoma in 2 cases. They had treatment depending on the pathological diagnosis. Of 4 asymptomatic cases, one with small focal tumour, with no findings suggesting malignant tumour with 11C-methioninePET or MRS, progressed to show typical clinical and image findings of DIPG in a year. For other three, they remain asymptomatic without progression with no treatment for 25months, 60months, and 65 months respectively. Malignant transformation was observed in one with biopsy-conformed oligoastrocytoma with no K27M-H3 mutations treated with chemotherapy and another with pilocytic astrocytoma treated with chemotherapy and radiotherapy. CONCLUSIONS: Though molecular findings such as K27M-H3 mutations can predict clinical outcome in some cases, it still remains difficult to diagnose and find treatment strategy of atypical brainstem tumours. The need and usefulness of nationwide registry study is warranted.