Walsh & Hoyt: Ependymoblastoma

Ependymoblastomas are rare, highly malignant tumors that occur mainly in the first few years of life. They are composed of uniform cells that do not show nuclear pleomorphism and contain only one nucleus. The cells are often arranged in true or pseudorosettes, and mitoses are numerous; however, other features of malignancy, including formation of giant cells, pseudopalisading, and vascular endothelial cell proliferation, are absent. Burger and Scheithauer and others classified ependymoblastomas as embryonal rather than ependymal in origin. They are not only locally invasive but metastasize extensively, both within and outside the CNS.