Ependymomas

Abstract

Ependymal neoplasms are a heterogenous group of neoplasms arising from the progenitors of the cells lining the ventricular system and the spinal central canal. During the last few years, significant novel data concerning oncogenesis, molecular characteristics and clinical correlations of these tumours have been collected, with a strong relevance for their pathological classification. The recently published 5th edition of WHO Classification of Central Nervous System Tumours integrates this novel knowledge and represents a substantial update compared to the previous edition. Concerning supratentorial ependymomas, the previous RELA fusion-positive ependymoma has been renamed into ZFTA fusion-positive and the novel YAP1 fusion-positive ependymoma subtype has been added. Posterior fossa ependymomas should now be allocated either to the Type A or Type B subtypes based on molecular profiling or using the H3 K27me3 immunohistochemical surrogate. Regarding spinal ependymomas, a novel subtype has been added based on a distinctive molecular trait, presence of MYCN amplification, and on the unfavourable outcome. Finally, myxopapillary ependymoma is now classified as a grade 2 tumour in accordance with its overall prognosis which mirrors that of conventional spinal ependymomas. The aim of this review is to present these changes and summarize the current diagnostic framework of ependymal tumours, according to the most recent updates.

Keywords: WHO classification; ependymoma; molecular pathology; myxopapillary ependymoma; subependymoma.