NIMG-67. REVISITING GLIOMATOSIS CEREBRI IN ADULT-TYPE DIFFUSE GLIOMAS: A COMPREHENSIVE ANALYSIS OF MANIFESTATION AND RISK FACTORS IN THE 2021 WHO CLASSIFICATION

Abstract

Abstract BACKGROUND To investigate the incidence, clinicopathologic and imaging correlations and prognostic implications of gliomatosis cerebri (GC) pattern in adult-type diffuse glioma patients reflecting the 2021 WHO classification. METHODS Retrospective chart and imaging review was performed in 1,211 adult-type diffuse glioma patients at a single institution between 2005 and 2021. Clinicopathologic and imaging features were compared amongst adult-type diffuse glioma patients with and without GC based on the 2021 WHO classification. Clinical and imaging risk factors for predicting IDH mutation status within GC patients were investigated. Survival analysis was performed in entire patients and in subgroup of IDH-wildtype glioblastoma patients to evaluate whether GC is an independent prognostic factor. RESULTS Total 99 patients (8.9% of entire patients) showed GC. The distribution of tumor type was significantly different in patients with GC compared with those without GC (P = 0.017); IDH-wildtype glioblastoma being most common (77.8% vs. 68.9%), followed by IDH-mutant astrocytoma (16.2% vs 16.9%), and being less common in oligodendroglioma (6.1% vs 16.5%). Contrast enhancement, necrosis, cystic change, hemorrhage, and GC type 2 were independent risk factors for predicting IDH mutation status in GC patients. GC remained as an independent prognostic factor (HR=1.55, P=0.031) in IDH-wildtype glioblastoma patients on multivariable analyses. CONCLUSIONS The incidence of GC is 8.9% in adult-type diffuse gliomas, with IDH-wildtype glioblastoma showing significantly higher risk of GC. Preoperative imaging features may predict IDH mutation status in GC patients. GC is an independent prognostic factor in IDH-wildtype glioblastoma, and promote recognition of this pattern in clinical settings.