A rare case of adult H3 K27-altered diffuse midline glioma with multifocal cerebrospinal fluid disseminated disease.

H3 K27-altered diffuse midline gliomas are a group of highly aggressive glial brain tumors that occur predominantly in children and carry a poor prognosis with limited treatment options. These are most often found in the thalamus, brainstem, or spinal cord. We report a case of a 28-year-old male with 1-month history of headache who was found to have multiple lesions involving the brainstem, cerebellum, pineal gland, and suprasellar region. On magnetic resonance imaging, the lesions demonstrated mild T2/FLAIR hyperintensity, T1 hypo- to isointensity, and rim contrast enhancement with central necrosis. Subtle diffusion restriction was noted across the lesions. Histopathological analysis following stereotactic biopsy confirmed the diagnosis of H3 K27-altered diffuse midline glioma.