Malignant meningioma in a child: CT and MR findings.

An 8-year-old boy was in good health until he presented with headache, vomiting, and deterioration of his mental status. CT revealed a bibbed mass approximately 4.5 cm in diameter in the tnigone of the right lateral ventricle. The mass was hyperdense relative to gray matter, with focal calcifications and acute hemorrhage (Figs. 1A and 1B). Edema was present in the adjacent white matter. The lateral and third ventricles were dilated. MR imaging at 1 .5 T revealed a mass with a signal intensity simiIan to that of gray matter on Ti -weighted images with high signal on proton density-weighted and T2-weighted images. Enhancement of the mass after IV administration of contrast material was heterogeneous (Figs. 1C and 1 D). The mass had well-defined borders with its center within the atrium of the right ventricle. No invasion of the surrounding brain was identified, but edema in the adjacent white matter was apparent. Areas of low signal intensity within the tumor, shown with all MR imaging sequences, corresponded to areas of calcification and acute hemorrhage identified on CT scans. After tumor resection, histologic examination revealed the neoplasm to be very vascular and to display the features of a meningothelial meningioma with nuclear pleomorphism, numerous mitotic figures (some of which were atypical), cells with prominent nucleoli, and foci of coagulative necrosis. The meningothelial nature of the cells was confirmed by electron microscopy and immunocytochemistry. The findings were those of a malignant meningioma. Two months after the initial presentation, MR imaging revealed recurrence of the tumor within the original tumor bed and multiple enhancing metastases within the right thalamic pulvinar and frontal lobes ofthe brain (Fig. 1E). Enhancing metastases also were identified within the subarachnoid spaces of the brain and spine (Fig. 1 F). The metastases were all less than 1 cm in diameter. Despite radiation therapy and chemotherapy, the child died 6.5 months after presentation.