Large Adult Spinal Diffuse Midline Histone H3 Lysine27-to-Methionine-Mutant Glioma With Intramedullary and Extramedullary Components Presenting With Progressive Hydrocephalus: A Case Report Highlighting Unique Imaging Findings and Treatment

Abstract

Diffuse midline glioma with histone H3 lysine27-to-methionine mutation (H3 K27M mutation) is a rare, aggressive tumor that is designated as World Health Organization (WHO) grade IV regardless of histologic features. Preoperative diagnosis remains challenging due to limited evidence regarding distinctive clinical and imaging characteristics. We describe the case of a young woman who presented with progressively worsening headaches due to communicating hydrocephalus. MR imaging with contrast of the cervical and thoracic spine revealed diffuse leptomeningeal enhancement with focal areas of intramedullary and subarachnoid T2 hyperintensity and enhancement, suggestive of a potential infectious process. Intraoperatively, no epidural pathology was identified, and with the differential diagnosis remaining broad, a second procedure was conducted involving intradural exploration and biopsy of a lesion. This was then identified as a diffuse midline glioma with H3 K27M mutation. The nonfocal clinical presentation in the setting of communicating hydrocephalus as well as the significant exophytic tumor growth and imaging findings made the initial diagnosis unique and challenging. This case, therefore, emphasizes the rare presentation of this tumor, and the need for further understanding of the clinical and imaging characteristics of this disease as well as the need for effective therapeutics.

Keywords: diffuse midline glioma; glioma; h3 k27m; high-grade glioma; spinal cord tumor.

Figure 1. Contrast MRI of the brain demonstrating abnormal enhancement at the ventral brainstem lining the interpeduncular cistern, with temporal horns of the lateral ventricles visible, suggesting hydrocephalus

MRI, Magnetic resonance imaging.

Figure 2. (A) and (B) T1-weighted sagittal MRI with IV contrast of the thoracic spine demonstrating the diffuse, heterogeneous leptomeningeal enhancement with loculated dorsal mass impinging the thecal sac (A) and intramedullary, exophytic mass (C). (B) Axial image of the slice indicated in (A) by the blue line. (D) Axial image of the slice indicated in (C) by the blue line. (E) and (G) T2-weighted sagittal MRI without contrast. (F) Axial image of the slice indicated in (E) by the blue line. (H) Axial image of the slice indicated in (G) by the blue line

MRI, Magnetic resonance imaging; IV, intravenous.

Figure 3. (A and B) H&E (40x) examination showed a cellular neoplasm with focally clear cytoplasm, marked nuclear pleomorphism, and hyperchromasia. Immunohistochemical studies (20x) demonstrating GFAP (C) and Ki-67 (D)

H&E, Hematoxylin and eosin; GFAP, glial fibrillary acidic protein.

Figure 4. (A) Treatment planning CT (sagittal view) displaying total craniospinal dose of 39.6 Gy with sequential boost dose to a total of 50.4 Gy. (B) Sagittal STIR MRI displaying 50.4 Gy dose. (C) T1 sagittal post-contrast MRI displaying 50.4 Gy dose. (D) PET/CT (sagittal view) displaying increased PET avidity in the spinal cord tumor

CT, Computed tomography; STIR, short-TI inversion recovery; MRI, magnetic resonance imaging; PET, positron emission tomography.