Ependymoma is a circumscribed glioma composed of uniform tumor cells and characterized by perivascular anucleate zones (pseudorosettes). Classic and anaplastic ependymomas are most commonly intracranial tumors, while myxopapillary ependymomas are more common in the spinal cord. Posterior fossa ependymomas predominate in children. No association between histologic grade (II vs. III) and progression-free or overall survival has been definitively established in ependymomas. Molecular profiling supports the existence of distinct molecular groups among ependymomas with strong relationships to anatomical sites. Supratentorial ependymomas are characterized by two groups with fusion genes involving RELA (in more than 70% of supratentorial ependymomas) or YAP1. Posterior fossa ependymomas are separated into PF-EPN-A (most common in infants and young children) and PF-EPN-B (most common in adolescents and adults). The outcome of ependymomas primarily depends on the extent of surgical resection, the use of radiation, as well as the molecular group. Gain of chromosome 1q is associated with poor outcome in posterior fossa ependymomas.
