title: Diagnostic revision of 206 adult gliomas (including 40 oligoastrocytomas) based on ATRX, IDH1/2 and 1p/19q status.
abstract: The diagnosis of 206 low and high grade adult gliomas, including 40 oligoastrocytomas, was revised based on the immunohistochemical reactivity for the ATRX protein, IDH1/2 mutation status and 1p/19q chromosomal status. All oligodendrogliomas kept the initial diagnosis. Astrocytomas did not change diagnosis in 30 of 36 cases (83.3 %); four of 36 (11.1 %) cases were reclassified as oligodendroglioma, one (2.8 %) as DNT and the other (2.8 %) as reactive gliosis. Oligoastrocytomas changed diagnosis in 35 of 40 (87.5 %) cases, being reclassified 22 of 40 (55 %) as astrocytoma, 11 of 40 (27.5 %) as oligodendroglioma and two of 40 (5 %) as reactive gliosis. Four (10 %) remained unclassifiable. In one case only (2.5 %), the diagnosis of oligoastrocytoma could not be excluded since tumor astrocytes and tumor oligodendrocytes coexisted in mixed tumor areas. In the GBM tumor subgroup, GBMO disappeared because they were not substantiated by molecular genetics. Pilocytic astrocytomas retained ATRX expression. Loss of nuclear ATRX protein expression was strongly associated to IDH1/2 mutations (p = 0.0001) and mutually exclusive with total 1p/19q co-deletion (p = 0.0001). In astrocytic tumors, loss of immunoreactivity for the ATRX protein was significantly associated to the ALT phenotype (p = 0.0003). The constitutive ATRX expression in microglia/macrophages may be misleading, especially in the identification of an oligodendroglial tumor infiltration. Of paramount importance in the recognition of oligodendroglial and astrocytic tumor cells were the double immunostainings for ATRX/GFAP, ATRX/IDH1R132H, ATRX/Iba-1 and ATRX/CD68.
authors: Research Center, Policlinico di Monza Foundation, Via Pietro Micca, 29, 13100, Vercelli, Italy.
authors: Marta
authors: M
authors: Mellai
authors: Research Center, Policlinico di Monza Foundation, Via Pietro Micca, 29, 13100, Vercelli, Italy.
authors: Laura
authors: L
authors: Annovazzi
authors: Unit of Pathology, Candiolo Cancer Institute, FPO, IRCCS Candiolo, Turin, Italy.
authors: Rebecca
authors: R
authors: Senetta
authors: Unit of Pathology, Candiolo Cancer Institute, FPO, IRCCS Candiolo, Turin, Italy.
authors: Carmine
authors: C
authors: Dell'Aglio
authors: Research Center, Policlinico di Monza Foundation, Via Pietro Micca, 29, 13100, Vercelli, Italy.
authors: Marta
authors: M
authors: Mazzucco
authors: Department of Medical Sciences, University of Turin, Turin, Italy.
authors: Paola
authors: P
authors: Cassoni
authors: Research Center, Policlinico di Monza Foundation, Via Pietro Micca, 29, 13100, Vercelli, Italy. davide.schiffer@unito.it.
authors: Davide
authors: D
authors: Schiffer
mesh_terms: D001254:Astrocytoma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D003937:Diagnosis, Differential; D017353:Gene Deletion; D005910:Glioma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D017628:Microglia / Q000378:metabolism; D009837:Oligodendroglioma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D000075924:X-linked Nuclear Protein / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; C538784:IDH2 protein, human; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human; C092332:ATRX protein, human; D000075924:X-linked Nuclear Protein
keywords: 1p/19q co-deletion; ALT; ATRX; IDH; Oligoastrocytoma