Histopathological grading of pediatric ependymoma: reproducibility and clinical relevance in European trial cohorts
David W Ellison*, Mehmet Kocak, Dominique Figarella-Branger, Giangaspero Felice, Godfraind Catherine, Torsten Pietsch, Didier Frappaz, Maura Massimino, Jacques Grill, James M Boyett and Richard G Grundy