Primary diffuse leptomeningeal glioneuronal tumors.

Area of Science:

• Neuro-oncology
• Neuropathology
• Radiology

Background:

• Diffuse leptomeningeal disseminated glioneuronal tumor (DL-GNT) is a rare neoplastic entity.
• Typically observed in children, DL-GNTs present as subarachnoid tumors without intraparenchymal involvement.

Observation:

• This report details three cases of DL-GNT, including two adult males and one child.
• Clinical presentations included seizures and headaches.
• Radiographic findings revealed characteristic leptomeningeal thickening and enhancement, with minimal superficial parenchymal lesions.

Findings:

• Histopathological analysis showed sheets of monotonous rounded cells.
• Immunohistochemistry revealed diffuse positivity for GFAP and synaptophysin, with scattered positivity for OLIG2 and NeuN.
• Electron microscopy confirmed astrocytic and neuronal differentiation.
• IDH-1 (H09) staining was negative in all cases.

Implications:

• DL-GNTs demonstrate unique radiological and histopathological characteristics.
• These tumors can occur in both pediatric and adult populations, affecting both supra- and infra-tentorial leptomeninges.
• Further molecular genetic studies are needed to establish DL-GNT as a distinct entity.