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Purpose: The cortical high-flow sign with the non-enhancing area was reportedly found to be more frequent with oligodendroglioma, IDH-mutant and 1p/19q codeleted (ODG IDHm-codel) than with IDH-wildtype or astrocytoma, IDH-mutant on arterial spin labeling (ASL) in diffuse gliomas. This study aimed to compare the identification rate of the cortical high-flow sign on ASL in patients with ODG IDHm-codel to that on dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI)., Methods: Participants consisted of 32 adult ODG IDHm-codel patients with pathologically confirmed. Subtraction images were generated from paired control and label images on ASL. For DSC, dynamic T2*-weighted perfusion weighted images were obtained after pre-bolus of gadolinium-based contrast agent. Regional cerebral blood flow/volume maps were generated based on the concentration-time curve and arterial input function. Tumor-affecting cortices without contrast enhancement on conventional MR imaging were targeted. The identification rate of the cortical high-flow sign was compared between ASL and DSC using the Pearson's Chi-Square test., Results: Frequency of the cortical high-flow sign was significantly higher on ASL (18/32, 56.3%; p < 0.001) than on DSC (5/32, 15.6%). All cases with the positive cortical high-flow sign on DSC were identified on ASL., Conclusion: ASL effectively identifies the cortical high-flow sign in ODG IDHm-codel, surpassing DSC in identification rates., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to investigate whether arterial spin labeling (ASL) features allow differentiation of oligodendroglioma, IDH-mutant and 1p/19q-codeleted (IDHm-codel) from diffuse glioma with IDH-wildtype (IDHw) or astrocytoma, IDH-mutant (IDHm-noncodel). Participants comprised 71 adult patients with pathologically confirmed diffuse glioma, classified as IDHw, IDHm-noncodel, or IDHm-codel. Subtraction images were generated from paired-control/label images on ASL and used to assess the presence of a cortical high-flow sign. The cortical high-flow sign was defined as increased ASL signal intensity within the tumor-affecting cerebral cortex compared with normal-appearing cortex. Regions without contrast enhancement on conventional MR imaging were targeted. The frequency of the cortical high-flow sign on ASL was compared among IDHw, IDHm-noncodel, and IDHm-codel. As a result, the frequency of the cortical high-flow sign was significantly higher for IDHm-codel than for IDHw or IDHm-noncodel. In conclusion, the cortical high-flow sign could represent a hallmark of oligodendroglioma, IDH-mutant, and 1p/19q-codeleted without intense contrast enhancement., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The revised 4th edition of the 2016 World Health Organization Classification of Tumors of the Central Nervous System (2016 CNS WHO) has introduced the integrated diagnostic classification that combines molecular and histological diagnoses for diffuse gliomas. In this study, we evaluated the molecular alterations for consecutive 300 diffuse glioma cases (grade 2, 56; grade 3, 62; grade 4, 182) based on this classification. Mutations in the isocitrate dehydrogenase (IDH) genes were common in lower grade glioma (LGG: grade2-3), and when combined with 1p/19q status, LGGs could be stratified into three groups except for four cases (Astrocytoma, IDH-mutant: 44; Oligodendroglioma, IDH-mutant and 1p/19q codeleted: 37; Astrocytoma, IDH-wildtype: 33). 1p/19q-codeleted oligodendrogliomas were clinically the most favorable subgroup even with upfront chemotherapy. In contrast, IDH-wildtype astrocytomas had a relatively worse prognosis; however, this subgroup was more heterogeneous. Of this subgroup, 11 cases had TERT promoter (pTERT) mutation with shorter overall survival than 12 pTERT-wildtype cases. Additionally, a longitudinal analysis indicated pTERT mutation as early molecular event for gliomagenesis. Therefore, pTERT mutation is critical for the diagnosis of molecular glioblastoma (WHO grade 4), regardless of histological findings, and future treatment strategy should be considered based on the precise molecular analysis., (© 2021. The Japan Society of Brain Tumor Pathology.)

Background: We previously reported a favorable outcome in a case series of patients with oligodendrogliomas treated with upfront chemotherapy; however, their progression-free survival (PFS) was relatively short considering their long-term overall survival (OS). This suggests that salvage treatments after progression were effective. However, the clinical impact of salvage treatments on outcomes of patients with recurrent oligodendrogliomas has not been precisely investigated., Methods: Our case series included 28 patients with newly diagnosed isocitrate dehydrogenase-mutant and 1p/19q-codeleted oligodendroglial tumors treated with upfront procarbazine, nimustine, and vincristine. Clinical outcomes and patterns of recurrence were reviewed retrospectively., Results: The median follow-up period of enrolled patients was 90.2 months. Disease progression occurred in 15 patients (53.6%), whereas the cancer appeared as local relapse alone in 14 (93.3%) patients. Salvage treatments were performed for all local relapses; thereafter, most of the subsequent progressions also appeared as resectable local relapses. The 5-year PFS and OS rates from the first progression were 30.3% and 92.9%, respectively. These relatively short PFS and favorable OS indicated the effectiveness of salvage treatment even after multiple progression. Thus far, 9 (60%) of 15 patients are deterioration-free with locally controlled lesions or complete remission; however, clinical deterioration was observed in 6 patients, and 4 of them experienced dissemination., Conclusions: In isocitrate dehydrogenase-mutant and 1p/19q-codeleted oligodendrogliomas, most of the tumors that demonstrated early progression appeared as local, nonlethal lesions, which have been well-controlled by salvage treatments. A precise diagnosis of oligodendrogliomas using molecular parameters is crucial to receive the best benefit from salvage treatment., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The most recent definition of glioblastoma with oligodendroglioma component (GBMO) assigned clinical significance to the observation of oligodendroglial foci within glioblastomas. However, the pathological mechanism of its histogenesis has not yet been determined. We report the genetic analysis of a GBMO case that evolved from an astrocyte lineage. A 37-year-old male underwent a third craniotomy for the removal of recurrent lesions of a secondary glioblastoma originating from a previous diffuse astrocytoma. The lesion in the right frontal lobe contained oligodendroglial foci within a glioblastoma background, while the remaining lesions showed only classic glioblastoma histology. Genetic analyses revealed distal 10q loss of heterozygosity (LOH) occurring de novo in the oligodendroglial tissue, as well as 10p, 17p LOH, and isocitrate dehydrogenase-1 gene (IDH1) mutations inherited from the previous lesions. The final recurrent glioblastoma underwent LOH on almost the entire of chromosome 10. Based on these results, the importance of an oligodendroglial component in glioblastomas may be limited.