HGG-50. TWO CASES OF H3 K27M-MUTANT DIFFUSE MIDLINE GLIOMA OF CERVICAL SPINAL CORD

BACKGROUND: “Diffuse midline glioma, H3 K27M-mutant’ was newly categorized as a separate pathological entity in the 2016 WHO classification, based on recently discovered mutation. Spinal cord glioma with H3 K27M-mutant is rare, so we reported the clinical course of two cases. CASE 1: A 17-year-old male presented with posterior headache and right limbs paralysis. MRI showed cervical spinal cord with expansion, T2-weighted high intensity and a part of enhancement. The biopsy revealed a diffuse midline glioma, H3 K27M-mutant. He received bevacizumab plus radiotherapy-temozolomide. In a few months, he had quadriplegia and cranial nerve paralysis and needed respirator. There was not expansion of mass, but intracranial dissemination. CASE 2: A 16-year-old male presented with posterior neck pain and right limbs paralysis. On brain stem and cervical spine, MRI findings were same to case 1. The biopsy was undergone and revealed H3 K27M mutation. He received bevacizumab in addition to radiotherapy-temozolomide. Although he also had quadriplegia, the progression of tumor has stopped. He has received chemotherapy with respirator at home. DISCUSSION: It was previously reported that the prognostic factors for diffuse midline glioma were tumor location, H3 K27M-mutation and age, but there are few relevant studies. The consensus on the treatment is also not clearly determined. Because the cervical spinal cord gliomas are rapidly advanced miserably, we added bevacizumab to standard radiotherapy-temozolomide for initial treatment. In addition, whole brain and spine radiation may be considered to avoid dissemination. Multicenter study is important to collect information and improve treatment of H3 K27M-mutant glioma.