Extra-axial ependymoma--case report.

A 13-year-old boy presented with a very unusual ependymoma extending extra-axially. Computed tomography demonstrated a tumor with a cyst and calcification adjacent to the dura and extending over the right occipital and parietal lobes. The cyst wall and solid tumor were enhanced postcontrast. Magnetic resonance imaging revealed that the solid tumor was isointense on T1-weighted images and a mixed iso- and high-intensity on T2-weighted images. The solid tumor and tissue surrounding the cyst were enhanced markedly by gadolinium-diethylenetriaminepentaacetic acid. Sagittal and coronal images demonstrated a multilocular tumor shadow. Cerebral angiography demonstrated a tumor fed by a posterior branch of the right middle meningeal artery but no feeders from the internal carotid and vertebral arteries. The tumor was removed en bloc. The histological diagnosis was clear cell-type ependymoma.