[Intracranial extracerebral glioma]

A case of solitary leptomeningeal extracerebral glioma is reported. A 75-year-old man was admitted to our hospital because of headache and right hemiparesis. CT scan and carotid angiography revealed a tumor in the left convexity. At operation, the tumor was located between the dura mater and the arachnoid membrane and adhered to the brain surface only in a limited area. Histological study including immunostain and electron microscopy showed the tumor as anaplastic oligo-astrocytoma. We speculate that our case may originate from a heterotopic glial nest in the dural border cell layer of dura mater. This explanation seems likely because the tumor was located mostly in the subdural space.