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JPTM > Ahead-of Print

doi: https://doi.org/10.4132/jptm.2019.07.15    [Epub ahead of print]
Reclassification of Mongolian Diffuse Gliomas According to the Revised 2016 World Health Organization Central Nervous System Tumor Classification
Enkhee Ochirjav1 , Tuul Baldandorj1 , Bayarmaa Enkhbat1 , Gheeyoung Choe2
1Department of Pathology, School of Biomedicine, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
2Department of Pathology, Seoul National University Bundang Hopsital, Seoul National University College of Medicine, Seongnam, Korea
Corresponding Author: Gheeyoung Choe ,Tel: +82-31-787-7711, Fax: +82-31-787-4012, Email: gychoe@snubh.org
Received: May 3, 2019;  Revised: July 12, 2019  Accepted: July 15, 2019.  Published online: August 2, 2019.

The 2016 World Health Organization (WHO) classification of central nervous system (CNS) tumors has been modified to incorporate the IDH mutation and 1p/19q co-deletion in the diagnosis of diffuse gliomas. In this study, we aimed to evaluate the feasibility and prognostic significance of the revised 2016 WHO classification of CNS tumors in Mongolian patients with diffuse gliomas.
A total of 124 cases of diffuse gliomas were collected, and tissue microarray blocks were made. IDH1 mutation was tested using immunohistochemistry and 1p/19q co-deletion status was examined using fluorescence in situ hybridization (FISH) analysis.
According to the 2016 WHO classification, 124 cases of diffuse brain glioma were reclassified as follows: 10 oligodendroglioma, IDHmut and 1p/19q co-deleted; 3 anaplastic oligodendroglioma, IDHmut and 1p/19q co-deleted; 35 diffuse astrocytoma, IDHmut; 11 diffuse astrocytoma, IDHwt, NOS; 22 anaplastic astrocytoma, IDHmut; 8 anaplastic astrocytoma, IDHwt, NOS; and 35 glioblastoma, IDHwt, NOS, respectively. The 2016 WHO classification presented better prognostic value for overall survival in patients with grade II tumors than traditional histological classification. Among patients with grade II tumors, those with oligodendroglioma IDHmut and 1p/19q co-deleted and diffuse astrocytoma IDHmut showed significantly higher survival than those with diffuse astrocytoma IDHwt, NOS (p<0.01).
Mongolian diffuse gliomas could be reclassified according to the new 2016 WHO classification. Reclassification revealed substantial changes in diagnosis of both oligodendroglial and astrocytic entities. We have confirmed that the revised 2016 WHO CNS tumor classification has prognostic significance in Mongolian patients with diffuse gliomas, especially those with grade II tumors.
Key Words: WHO, Classification, Glioma, Isocitrate dehydrogenase, Chromosome deletion