MATERIAL and METHODS: Pediatric patients with midline gliomas who underwent surgery in our clinic between March 2016 and November 2019 were included. Tissue samples were obtained through surgical excision, open biopsy, or stereotactic biopsy. All samples were analyzed for ATRX, BRAFV600E, IDH1/2, H3K27M, and H3G34R mutations, EGFR and PGFRA amplifications, and PTEN loss.

RESULTS: There were 7 (43.8%) female and 9 (56.2%) male pediatric patients in the study. Eight patients had thalamic, 5 patients had pontine, 2 patients had medulla oblongata and one patient had brachium pontis tumors. Presenting symptoms were headache, disequilibrium, ophthalmoplegia, and panic attack. Eleven tumors showed H3K27M mutation and were diagnosed as diffuse midline gliomas. BRAFV600E, ATRX mutations, PTEN loss, and EGFR amplifications were other molecular alterations detected within tumor samples. Patients with H3K27M mutant tumors had a shorter life span. Five patients were enrolled in an ONC201 trial.

CONCLUSION: Although most midline gliomas are not amenable to gross total excision, obtaining tissue samples is mandatory for determining patients? exact diagnoses, tailored treatment plans, and eligibility for clinical trials. Stereotactic biopsy for midline gliomas is a safe and effective method. Keywords : Midline glioma, ONC201, Stereotactic biopsy, Diffuse glioma, Treatment