Clivus Intraosseous Meningioma Mimicking Chordoma.

A 78-year-old woman with progressive worsening vertigo and new onset of diplopia. Neurological examination revealed bilateral abducens nerve paralysis and gait disturbance with truncal ataxia. Neuroimaging revealed a mass lesion within the clivus with brain stem compression. The patient was operated with provisional diagnosis of clivus chordoma by neuro-navigation-guided extended endoscopic endonasal approach. Subtotal resection of the tumor was achieved with no intra- or postoperative complications. Histopathologic examination revealed intraosseous meningioma (WHO grade I). To the authors' best knowledge this is the first case reporting clivus site of intraosseous meningioma.