Tentorial Traversal by Ependymoblastoma

An otherwise normal 28-month-old boy had a 2-month history of intermittent vomiting and a 1-week history of headaches. Neurologic examination was normal except for a right extensor plantar response. Axial CT scan (Fig . 1A) showed a large primarily intraventricular mass occupying the posterior left cerebral hemisphere. Directly caudad to this, a similar tumor was present in the left cerebellar hemisphere displacing the brainstem and fourth ventricle (Fig. 1 B). No tumor was seen in the tentorial hiatus. Extensive patchy areas of increased density scattered throughout the tumor were interpreted as either blood or calcification . Coronal MR images (Fig. 1 C) showed traversal of the supratentorial tumor through the tentorium into the left cerebellar hemisphere. Scattered throughout the tumor were large irregular areas of hemorrhage that were identified by increased signal intensity on T1 sequences. The areas of increased signal corresponded to the areas of increased attenuation on CT scans. At surgery, a large invasive necrotic tumor of ventricular origin was resected partially. It extended through a large hole in the tentorium to invade the cerebellum. Microscopically, the tumor was densely cellular and composed of uniform cells with hyperchromatic nuclei and , frequently , mitotic figures. Scattered small central-lumen rosettes (true rosettes) and tubules with multiple layers of nuclei were present. Occasionally, gliovascular structures were seen in which blood vessels were surrounded by radiating processes of tumor cells that had nuclei in the antipodal position. No calcium was seen. Pathologic diagnosis was ependymoblastoma. Chemotherapy was attempted without success. The patient died 3 months after presentation .