Embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma, and medulloepithelioma share molecular similarity and comprise a single clinicopathological entity

Andrey Korshunov, Dominik Sturm, Marina Ryzhova, Volker Hovestadt, Marco Gessi, David T. W. Jones, Marc Remke, Paul Northcott, Arie Perry, Daniel Picard, Marc Rosenblum, Manila Antonelli, Eleonora Aronica, Ulrich Schüller, Martin Hasselblatt, Adelheid Woehrer, Olga Zheludkova, Ella Kumirova, Stephanie Puget, Michael D. Taylor, Felice Giangaspero, V. Peter Collins, Andreas von Deimling, Peter Lichter, Annie Huang, Torsten Pietsch, Stefan M. Pfister, Marcel Kool

Three histological variants are known within the family of embryonal rosette-forming neuroepithelial brain tumors. These include embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL), and medulloepithelioma (MEPL). In this study, we performed a comprehensive clinical, pathological, and molecular analysis of 97 cases of these rare brain neoplasms, including genome-wide DNA methylation and copy number profiling of 41 tumors. We identified uniform molecular signatures in all tumors irrespective of histological patterns, indicating that ETANTR, EBL, and MEPL comprise a single biological entity. As such, future WHO classification schemes should consider lumping these variants into a single diagnostic category, such as embryonal tumor with multilayered rosettes (ETMR). We recommend combined LIN28A immunohistochemistry and FISH analysis of the 19q13.42 locus for molecular diagnosis of this tumor category. Recognition of this distinct pediatric brain tumor entity based on the fact that the three histological variants are molecularly and clinically uniform will help to distinguish ETMR from other embryonal CNS tumors and to better understand the biology of these highly aggressive and therapy-resistant pediatric CNS malignancies, possibly leading to alternate treatment strategies.