NIMG-53. IMAGING FEATURES AND CONSIDERATION OF PROGRESSION PATTERN OF DIFFUSE HEMISPHERIC GLIOMAS, H3 G34-MUTANT

Abstract

Abstract BACKGROUND Diffuse hemispheric gliomas, H3 G34-mutant (DHGs-G34m) are newly recognized pediatric-type diffuse high-grade gliomas. We describe detail imaging features of seven cases of DHGs-G34m and consider about progression pattern of DHGs-G34m. RESULTS H3 G34R or H3 G34V was detected by sanger sequencing in all tumors. Mean age of onset was 16.5 years (range: 10-26). Tumors were located on frontal (2), parietal (2), temporal lobe (1) and insular cortex (1), respectively. In one case, gliomatosis cerebri-like multiple lesions involving the cortex and basal ganglia occurred. Magnetic resonance imaging showed T2/FLAIR high lesions with poor contrast enhancement in all cases. All tumors harbored restriction of diffusion. Cystic component and hemorrhage were observed in five and three cases, respectively. Six patients underwent preoperative positron emission tomography. Strong accumulation of methionine and partial accumulation of FDG in all cases. All tumors harbored T2/FLAIR high lesions in the deep white matter, most of which showed methionine accumulation. All patients underwent surgery (total resection in one case, partial resection in five cases, and biopsy in one case) followed by radiation chemotherapy. The mean progression free survival was 9.9 months (range: 1.6-33.1 months). All tumors harbored diffuse infiltration along the white matter, which was temporarily reduced by bevacizumab, but eventually invaded into cerebral peduncle via pyramidal tract and into contralateral brain via corpus callosum or anterior commissure in six cases. Extensive infiltration of tumor cells into the contralateral brain and brain stem was confirmed histopathologically in the autopsy brain of one case. The mean overall survival was 21.6 months (range: 8.9-48.3 months). CONCLUSION DHGs-G34m showed deep white matter infiltration from the time of initial onset, which made gross total resection difficult. Residual lesions extensively infiltrated along the white matter and eventually invaded the brainstem and contralateral brain, leading to death.