Solitary primary intracranial leptomeningeal glioblastoma invading the normal cortex: Case report.

Solitary primary intracranial leptomeningeal glioma (PLG) is a rare entity of glioma. PLG arises from the heterotopic glial tissue in the subarachnoid space and usually grows there without parenchymal invasion. The present study reported a case of solitary PLG, pathologically diagnosed as glioblastoma, that invaded the temporal cortex and finally disseminated to the spinal cord. A 55-year-old woman had headaches and visited Nihon University, Itabashi Hospital. Head magnetic resonance imaging showed a solid mass mainly located in the right middle fossa extending to the frontal base with strong enhancement effect after contrast medium injection. A conventional angiogram showed a tumor arising from the middle meningeal artery. Fronto-temporal craniotomy was performed to remove the tumor. During reflection of the dura matter, there were numerous small vessels connecting the dura matter and the cortical surface. The tumor was located in the Sylvian fissure and extended around the middle cerebral artery. The border between the tumor and the normal temporal lobe was unclear. Temporal lobectomy was done, but the tumor was left around the perforators of the middle cerebral artery. Hematoxylin and eosin staining showed typical glioblastoma with high cellularity, mitosis, pseudopallisading and vascular proliferation. The tumor cells were immunohistochemically negative for isocitrate dehydrogenase (IDH)1-R132H indicating glioblastoma, IDH-wild type. The patient received chemotherapy and radiation therapy, and was discharged from the hospital. Six months later, local regrowth and spinal dissemination were found. Despite additional chemotherapy and radiation therapy, the tumor became uncontrollable and the patient succumbed. Only 15 cases of solitary PLGs have been reported previously. The IDH status of these tumors have not been investigated in most cases; however, pathological grading varies from lower to higher grade glioma. Together with the pathological difference of astrocytic or oligodendrocytic tumors, solitary PLGs may develop due to various gene alterations similar to intra-axial gliomas.