ABSTRACT
In the World Health Organization (WHO) classification of tumors of the nervous system, the medulloblastoma is placed among embryonal neuroepithelial tumors (Kleihues and Cavanee, 2000). It is a tumor of the cerebellum, and encompasses a morphologically heterogeneous group of neoplasms. This diversity is reflected in distinct sets of molecular abnormalities, which may signify divergent mechanisms of pathogenesis/histogenesis (Ellison, 2002).
