Imaging patterns of multifocal gliomas.

We reviewed the imaging characteristics of 51 consecutive cases of cerebral glioma with multiple foci of involvement. In 26 patients, multifocality was present at the initial diagnosis, whereas in 25, it developed at a later stage. Thirty-two patients were studied with MRI, 13 with CT, and six with both imaging techniques. In 14 cases, no apparent dissemination route was identified; these tumors were presumed to be true multicentric gliomas. In the rest of the cases, various patterns of spread from a primary site were evident or suggested, and the tumors were denoted as multifocal. The most frequent dissemination route in the latter group was the meningeal-subarachnoid space, followed by the subependymal, intraventricular route and direct brain penetration. Multifocal gliomas are more frequent than generally believed and, therefore, multiple cerebral masses should be thoroughly evaluated and not always presumed to be of metastatic origin.