These tumors are typically slow growing, arising from ciliated ependymal cells. Two thirds of ependymomas occur in the fourth ventricle arising from the floor of the ventricle. Sometimes called a toothpaste lesion, they may fill the fourth ventricle and grow out into the cisterna magna and spinal canal through the foramen of Luschka or Magendie. Lesions appear heterogeneous on imaging, exhibit heterogeneous enhancement, and are usually well defined with lobulated margins.