Validation Of The New Glioma Who Classification In The French Pola Network: Analysis Of 1041 Cases.

2015Background: The upcoming WHO classification of gliomas will be refined taking into account the robust molecular alterations of gliomagenesis: the 1p19q codeletion and IDH1/2mutations. Methods: All cases of high-grade oligodendroglial tumors sent for central pathological review and included into the French nation-wide POLA network were reclassified according the upgrading of the 4th WHO classification that integrates pathological features and molecular data. Immunohistochemical expression of IDH1R132H, and ATRX, 1p19q codeletion, chromosome 7p gain and chromosome 10q loss by genomic-array and IDH1/2and histone K27M mutational statuses by sequencing were evaluated. Results: 1041 patients were included with a median age at diagnosis of 50.4 years (range, 17.1-84.4). Based on the new histo-molecular classification, diagnoses were: anaplastic oligodendroglioma with 1p19q codeletion (32.5%), anaplastic astrocytoma IDH mutated (IDHmt) (11.0%), anaplastic astrocytoma IDHwild-type (IDHwt) (5.3%), glioblastoma ...