RESUMEN
Glioblastoma (formerly named glioblastoma multiforme) is the most common primary central nervous system tumor, representing 45% of all cases and 15% of all intracranial neoplasms [1]. Its typical radiologic findings and localization make it often a lesion easy to diagnose. In MRI it usually appears as an irregularly shaped cystic lesion with ring contrast enhancement in T1-weighted images, localized in subcortical white matter and deep gray matter nuclei of the cerebral hemispheres. It involves more frequently the frontotemporal region followed by parietal lobes [1]. Few articles in literature described cases of intraventricular glioblastomas, defining those as secondary ventricular tumors because of their probable origin primarily from cerebral tissue with consequent transependymal development [2, 3]. Atypical presentations of these tumors make it more difficult to clearly differentiate them from other lesions more commonly located in the ventricular system. We describe a case with a unique radiological presentation: an intraventricular glioblastoma lying entirely within the ventricular walls, involving all the ventricular system, without mass effect or nodular parenchymal lesions.