Reclassification of Mixed Oligoastrocytic Tumors Using a Genetically Integrated Diagnostic Approach

Abstract

BackgroundMixed gliomas, such as oligoastrocytomas (OA), anaplastic oligoastrocytomas, and glioblastomas (GBMs) with an oligodendroglial component (GBMO) are defined as tumors composed of a mixture of two distinct neoplastic cell types, astrocytic and oligodendroglial. Recently, mutations ATRX and TP53, and codeletion of 1p/19q are shown to be genetic hallmarks of astrocytic and oligodendroglial tumors, respectively. Subsequent molecular analyses of mixed gliomas preferred the reclassification to either oligodendroglioma or astrocytoma. This study was designed to apply genetically integrated diagnostic criteria to mixed gliomas and determine usefulness and prognostic value of new classification in Korean patients.MethodsFifty-eight cases of mixed OAs and GBMOs were retrieved from the pathology archives of Seoul National University Hospital from 2004 to 2015. Reclassification was performed according to genetic and immunohistochemical properties. Clinicopathological characteristics of each subgroup were evaluated. Overall survival was assessed and compared between subgroups. ResultsWe could reclassify all mixed OAs and GBMOs into either astrocytic or oligodendroglial tumors. Notably, 29 GBMOs could be reclassified into 11 cases of GBM, IDH-mutant, 16 cases of GBM, IDH-wildtype, and two cases of anaplastic oligodendroglioma, IDH mutant. Overall survival was significantly different among these new groups (p<.001). Overall survival and progression-free survival were statistically better in gliomas with IDH mutation, ATRX mutation, no microscopic necrosis, and young patient age (cut off, 45 years old). ConclusionsOur results strongly suggest that a genetically integrated diagnosis of glioma better reflects prognosis than former morphology-based methods.

Dynamic susceptibility contrast and diffusion MR imaging identify oligodendroglioma as defined by the 2016 WHO classification for brain tumors: histogram analysis approach

“…Fourth, IDH1/2 status was not available in all the patients, (57,7% of patients cohort). However, a large number of studies shows that IDH1/2 mutation occurs in all 1p19q-codeleted tumors and the great majority of diffuse gliomas grade II/III also falls into the IDH mutant category [44,6,7,45,46,24,47]. Finally, as is true across all imaging modalities, the manual tumor outlining performed in our study is subjective and reproducibility may be challenged when used in combination with advanced imaging techniques.…”

The prognostic significance of p16 expression pattern in diffuse gliomas

“…The probes used to perform FISH were as follows: Vysis LSI 1p36 SpectrumOrange/1q25 SpectrumGreen Probes and Vysis LSI 19q13 SpectrumOrange/ 19p13 SpectrumGreen Probes (Abbott Molecular, Vysis, Des Plaines, IL, USA); Vysis LSI CDKN2A SpectrumOrange/CEP 9 SpectrumGreen Probes (Abbott Molecular); Vysis LSI EGFR SpectrumOrange/CEP 7 SpectrumGreen Probes (Abbott Molecular); Vysis LSI PTEN/CEP 10 Dual Color Probe (Abbott Molecular). Each molecular test was performed and interpreted as previously described [23,24]. Homozygous deletion of the CD-KN2A gene was determined when > 15% of tumor cells lost two test signals in the presence of at least one reference signal in 100 non-overlapping counted nuclei [25].…”

Heterogeneity of oligoastrocytoma: morphology, surgery, and survival in the series of 163 patients. Retrospective study

“…Oligoastr oc y toma (OA) is a subset of brain tumors that present with an appearance of mixed astrocytic and oligodendroglioma glial cell [1]. About 2.3-23 % of all reported gliomas are diagnosed as oligoastrocytoma, the OA incidence rate is 0.16-1.47 cases per 100,000 population per year [2][3][4].…”

“…It could be explained by the lack of clear histological criteria for this tumor. Only in 1993 OA was included into the WHO classification of brain tumors [3,5]. No purposeful histological studies of OA on significant material have Ukrainian Neurosurgical Journal pISSN 1810-3154 eISSN 2412-8791…”