Ewing's Sarcoma peripheral primitive neuroectodermal tumor
Usually arises from the floor of the 4th ventricle
Typically squeezes out the foramen of Luschka.
Chen et al. encountered a patient with medulloblastoma in which the neuroimaging findings mimicked those of dysplastic cerebellar gangliocytoma. In patients with a posterior fossa tumor suggestive of a dysplastic gangliocytoma on neuroimaging studies, a pathologic confirmation is necessary 1).