Fig. 6. Illustrative case (Case 18). Preoperative MRI and CT images (A-C) and postoperative MRI and CT images (D-F). A 20-year-old female patient presented with progressive left side weakness (grade 3). Images reveals right thalamic mass with hydrocephalus. The tumor was removed subtotally and the patient was diagnosed as diffuse midline glioma, H3 K27M altered. Note that hydrocephalus is resolved after resection. After resection, weakness improved to grade 4 and hydrocephalus remains resolved for 4 months till progression.