Primary malignant rhabdoid tumor of the brain: clinical, imaging, and pathologic findings.

PURPOSE To describe the imaging and pathologic findings of malignant rhabdoid tumor (MRT), a rare primary brain neoplasm affecting children. METHODS The CT and/or MR features, pathologic findings, and clinical records of three children with primary MRT of the brain were retrospectively reviewed. RESULTS The tumors, large, left-sided cerebral masses, were intraventricular in two cases. MR images in one patient showed T1- and T2-weighted signal intensity isointense with gray matter. Multiple necrotic/cystic foci were present in all cases, with two showing a patchy pattern of enhancement on CT and MR. The diagnosis of MRT was documented by ultrastructural and immunohistochemical studies. All patients had normal abdominal CT scans, excluding the possibility of primary renal rhabdoid tumor metastatic to the brain. The disease progressed rapidly in each case, despite surgery, chemotherapy, and craniospinal irradiation, with serial imaging evidence of tumor regrowth at the primary site and the development of metastatic satellite lesions. CONCLUSIONS The diagnosis of primary MRT of the brain can be made only pathologically; however, the nonspecific imaging findings in these cases suggest that MRT should be considered in the differential diagnosis of large childhood intracranial neoplasms.