Ewing's Sarcoma peripheral primitive neuroectodermal tumor

Fourth ventricle ependymoma:

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⁾.