Meningioma of the fourth ventricle

Meningiomas are primary meningeal based tumors of the central nervous syste m that rarely are located strictly within the fourth ventricle. We report a 72-year-old man operated upon for such a tumor. The pre-operative magnetic resonance images revealed a well circumscribed mass in the fourth ventricl e that exhibited a low signal on T1-weighted magnetic resonance images and homogenously enhanced with gadolinium. By light microscopy the tumor was co mposed of tightly packed spindle cells separated by collagen. Immunohistoch emistry showed the tumor cells to be positive for vimentin and epithelial m embrane antigen, and negative for glial fibrillary acidic protein. Electron microscopy revealed typical findings of meningioma, including interdigitat ing cell processes, desmosomes, and intermediate filaments. Although rare, fibroblastic meningioma must be included in the differential diagnosis of a fourth ventricular spindle cell tumor in elderly patients.