10184-BT-14 CLINICAL FEATURE OF HEMISPHERIC GLIOMA WITH H3F3A, PEDIATRIC-TYPE HIGH GRADE GLIOMA, H3 K27-ALTERED, NEC AND DIFFUSE HEMISPHERIC GLIOMA, H3 G34-MUTANT, CNS WHO GRADE 4

Abstract

Abstract INTRODUCTION Diffuse midline glioma (DMG), H3K27-altered, is a CNS WHO grade 4 glioma that usually located mainly in the brainstem, thalamus and spinal cord. However, DMG located in non-midline lesions are now described as pediatric-type high grade glioma, H3K27-altered, NEC (NDMG). On the other hand, diffuse hemispheric glioma, H3G34-mutant (DHG) located in the cerebral hemispheres, and is classified under the WHO 2021 classification. It is unknown that the differences in clinical characteristics of these hemispheric tumors with H3F3A mutations. In the present study, we report a comparative study of the clinical characteristics of two groups of NDMG and DHG. METHODS Among 4128 brain tumor samples collected in the Kansai Network for Molecular Diagnosis of Central Nervous System Tumors, 16 NDMG and 9 DHG cases were examined for comparison of clinical characteristics. RESULTS There were no differences in gender, tumor location, or pathology between NDMG and DHG. The median age was 47.3 years in NDMG and 26.2 years in DHG, and NDMG was significantly older than DHG (p=0.003). There was no significant difference in MGMT promoter methylation between NDMG and DHG (p=0.087). The Kaplan-Meier survival curve showed no significant difference, with a median survival of 495 days for NDMG and 587 days for DHG (p=0.765). There was no significant different survival rate between WHO grade 3 (n=15) and grade 4 (n=9) for pathological diagnosis. DISCUSSION AND CONCLUSION We compared the clinical characteristics of NDMG and DHG. There are some reports that NDMG and DHG gliomas located in non-midline lesion. Removing much tumor volume may improve the prognosis of non-midline glioma. We discuss the gliomas with H3F3A mutations located in a hemispheric lesions by literature review.