PATH-07. CLINICAL AND RADIOGRAPHIC FEATURES OF DIFFUSE GLIOMA MOLECULAR SUBTYPES IN ACCORDANCE WITH THE 2021 CNS5 WHO CLASSIFICATION

Abstract BACKGROUND The incorporation of molecular parameters into WHO CNS5 has led to reclassification of many gliomas. We undertook to describe presenting clinical and radiographic features of diffuse adult gliomas according to CNS5 category. METHODS We reviewed pathology reports, clinical and MRI data at presentation of 972 adult patients with glioma diagnosed between 1/2010-2/2022. Continuous variables were presented as median; categorical variables as numbers and percentages, and comparison were performed using chi-square test. RESULTS 736 patients had sufficient data for CNS5 re-classification and were included in the analysis: Grade 2 IDH-mutant (IDHmut) astrocytoma (A2) n=69, grade 3 IDHmut astrocytoma (A3) n=37, grade 4 IDHmut astrocytoma (A4), n=32, grade 2 oligodendroglioma (O2) n=60, grade 3 oligodendroglioma (O3) n=23, and grade 4 IDH-wildtype glioblastoma (GBM) n=515. Age at presentation significantly differed between grade 2&3 gliomas and grade 4 (mean age:39 versus 61.7; p<0.001); A4 were also younger than GBM (39.8 versus 63.1). A majority in all categories except grade 2 gliomas were male. Seizure was more common in IDHmut gliomas than GBM (58.4% versus 31.8%;p<0.001), while cognitive impairment was more common in GBM than in IDHmut gliomas (64.4% versus 34.4%;p<0.001) and in A4 (64% versus 40.6%;p=0.013). Focal deficits at presentation were more frequent in GBM than in IDHmut gliomas (74.2% versus 30.5%;p<0.001), but not significantly different compared to A4 (74.2% versus 58.1%;p=0.06). Contrast enhancement on MRI was more frequent in GBM compared to IDHmut gliomas (93% versus 48%;p<0.001), but similar frequency with A4 (93% versus 96%;p=1.00). The minimum ADC was significantly higher in IDHmut glioma including A4 than GBM(p<0.001). Calcification was more common in oligodendroglioma than astrocytoma and GBM (p<0.001), and more frequent in A4 than GBM(p=0.016). CONCLUSION Significant differences in the clinical presentation and radiologic features exist among CNS5 glioma subtypes, informing potential diagnosis, management and prognosis at initial presentation.