Cerebellar gliomas with exophytic growth--three case reports.

Three patients presented with cerebellar hemispheric astrocytic tumors which showed an exophytic growth pattern. The neuroimaging appearances of these cases mimicked a cerebellopontine angle tumor in two cases, and a posterior fossa extra-axial tumor in the other, which arose from the left cerebellar hemisphere with exophytic extension into the left crural and quadrigeminal cisterns and compressed the midbrain directly. All patients underwent surgical resection, and two patients also received adjuvant radiation therapy and chemotherapy. Intraoperative findings confirmed that the tumors had intramedullary origins from the cerebellar hemisphere, and extended exophytically into the subarachnoid space forming an extra-axial mass lesion. The histological diagnoses were mixed malignant oligo-astrocytoma (grade III), astrocytoma (grade II), and glioblastoma (grade IV). Cerebellar gliomas with exophytic growth to the cerebellopontine angle cistern should be considered in the differential diagnosis of cerebellopontine angle tumors.