Spinal Cord Diffuse Midline Gliomas With H3 K27m-Mutant: Clinicopathological Features and Prognosis.

Background "Diffuse midline glioma, H3 K27M-mutant" (DMG) mainly arises within the pontine, thalamic, and spinal cord regions. Because of the rarity of spinal cord gliomas, the general knowledge surrounding DMGs is mainly based on pontine and thalamic gliomas, whereas tumor location tends to influence the clinicopathological features and prognosis. Objective To determine the clinicopathological characteristics and molecular profiles of DMGs located in the spinal cord. Methods The clinical and molecular pathologic features and prognosis were comprehensively analyzed in a series of 44 patients with spinal cord DMGs. Results The median age was 36 yr, and 88.7% of patients (39/44) were adults (≥18 yr). Histopathologically, malignant grades included grade II (16 cases), grade III (20 cases), and grade IV (8 cases). Compared with patients with histological grade IV, patients with lower histological grade (grade II/III) were older (37 vs 24 yr, P = .020) and were associated with longer overall survival (24.1 vs 8.6 mo, P = .007). All 30 tested tumors were isocitrate dehydrogenase (IDH) wild type, and 96% of cases (22/23) presented with unmethylated O6-methylguanine-DNA methyltransferase. Univariate and multivariate analyses showed that histological grade and presurgery McCormick Scale scores were independent prognostic factors for overall survival, whereas extensive surgical resection and chemoradiotherapy were not significantly associated with improved survival. The most frequent anatomic locations were the cervical enlargement (C4-T1, n = 16) and conus medullaris (T12-L1, n = 13), which exhibited distinctive clinical characteristics and molecular features. Conclusion The findings provide guidelines for the evidence-based practice of the specialized management of spinal cord DMGs.