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Since the World Health Organization (WHO) 2016 revision, the number of molecular markers required for diffuse gliomas has increased, placing a burden on clinical practice. We have established an in‐house, molecular diagnostic platform using Senshin‐Iryo, a feature of Japan's unique healthcare system, and partially modified the analysis method in accordance with the WHO 2021 revision. Herein, we review over a total 5 years of achievements using this platform. Analyses of IDH, BRAF, and H3 point mutations, loss of heterozygosity (LOH) on 1p/19q and chromosomes 10 and 17, and MGMT methylation were combined into a set that was submitted to Senshin‐Iryo as “Drug resistance gene testing for anticancer chemotherapy” and was approved in August 2018. Subsequently, in October 2021, Sanger sequencing for the TERT promoter mutation was added to the set, and LOH analysis was replaced with multiplex ligation‐dependent probe amplification (MLPA) to analyze 1p/19q codeletion and newly required genetic markers, such as EGFR, PTEN, and CDKN2A from WHO 2021. Among the over 200 cases included, 54 were analyzed after the WHO 2021 revision. The laboratory has maintained a diagnostic platform where molecular diagnoses are confirmed within 2 weeks. Initial expenditures exceeded the income from patient copayments; however, it has gradually been reduced to running costs alone and is approaching profitability. After the WHO 2021 revision, diagnoses were confirmed using molecular markers obtained from Senshin‐Iryo in 38 of 54 cases (70.1%). Among the remaining 16 patients, only four (7.4%) were diagnosed with diffuse glioma, not elsewhere classified, which was excluded in 12 cases where glioblastoma was confirmed by histopathological diagnosis. Our Senshin‐Iryo trial functioned as a salvage system to overcome the transition period between continued revisions of WHO classification that has caused a clinical dilemma in the Japanese healthcare system. [ABSTRACT FROM AUTHOR]

The mutation p.K27M in H3F3A (H3 K27M mutation) is mainly detected in diffuse midline glioma. However, recent studies have demonstrated that H3 K27M mutation could also be observed in a subset of gangliogliomas. Importantly, most H3 K27‐mutated ganglioglioma cases also harbor BRAF V600E mutation. Herein, we report a rare case of H3 K27M‐mutated ganglioglioma grade 3 without BRAF mutation arising in the medial temporal lobe in an elderly man. A small biopsy specimen was sampled. The pathological diagnosis was diffuse astrocytoma. The tumor progressed gradually during an 18‐month follow‐up period. Gadolinium enhancement on magnetic resonance imaging was noted 36 months after the biopsy. The patient was referred to a hospital for tumor resection. Histological analysis of resected specimens led to a diagnosis of ganglioglioma grade 3 with H3 K27M mutation. The patient underwent concurrent temozolomide chemotherapy with radiotherapy. Although the patient's condition deteriorated after chemotherapy due to disease progression, he survived for more than 23 months after tumor resection. We present this rare case and discuss the involvement of H3 K27M mutation in ganglioglioma grade 3. [ABSTRACT FROM AUTHOR]

Objective: Accumulating evidence from recent molecular diagnostic studies has indicated the prognostic significance of various genetic markers for patients with glioblastoma (GBM). To evaluate the impact of such genetic markers on prognosis, we retrospectively analyzed the outcomes of patients with IDH‐wildtype GBM in our institution. In addition, to assess the impact of bevacizumab (BEV) treatment, we compared overall survival (OS) between the pre‐ and post‐BEV eras. Methods: We analyzed the data of 100 adult patients (over 18 years old) with IDH‐wildtype GBM from our database between February 2006 and October 2018. Genetic markers, such as MGMT methylation status, EGFR amplification, CDKN2A homozygous deletion, and clinical factors were analyzed by evaluating the patients' OS. Results: CDKN2A homozygous deletion showed no significant impact on OS in patients with methylated MGMT status (p = 0.5268), whereas among patients with unmethylated MGMT status, there was a significant difference in OS between patients with and without CDKN2A homozygous deletion (median OS: 14.7 and 16.9 months, respectively, p = 0.0129). This difference was more evident in the pre‐BEV era (median OS: 10.1 and 15.6 months, respectively, p = 0.0351) but has become nonsignificant in the post‐BEV era (median OS: 16.0 and 16.9 months, respectively, p = 0.1010) due to OS improvement in patients with CDKN2A homozygous deletion. However, these findings could not be validated in The Cancer Genome Atlas cohort. Conclusions: MGMT and CDKN2A status subdivided our cohort into three race‐specific groups with different prognoses. Our findings indicate that BEV approval in Japan led to OS improvement exclusively for patients with concurrent unmethylated MGMT status and CDKN2A homozygous deletion. [ABSTRACT FROM AUTHOR]

Here, we report a juvenile (18‐year‐old male) case of epilepsy‐associated, isocitrate dehydrogenase wild‐type/histone 3 wild‐type diffuse glioma with a rare BRAF mutation and a focal atypical feature resembling diffuse astrocytoma. The patient presented with refractory temporal lobe epilepsy. Subsequently, magnetic resonance imaging revealed a hyperintense lesion in the right temporal lobe on fluid attenuated inversion recovery images. The patient underwent right lateral temporal lobectomy and amygdalohippocampectomy. Histopathologically, the tumor showed isomorphic, diffuse, infiltrative proliferation of glial tumor cells and intense CD34 immunoreactivity. The tumor cells were immunonegative for isocitrate dehydrogenase 1 (IDH1) R132H and BRAF V600E. Notably, the tumor cells showed the lack of nuclear staining for α‐thalassemia/mental retardation syndrome, X‐linked (ATRX). In addition, the Ki‐67 labeling index, using a monoclonal antibody MIB‐1, was elevated focally at tumor cells with p53 immunoreactivity. Molecular analyses identified a BRAFA598T mutation, the first case reported in a glioma. BRAFA598T is predicted to result in loss of kinase action; however, inactive mutants can stimulate mitogen‐activated protein kinase kinase (MEK)‐extracellular signal‐regulated kinase (ERK) signaling through CRAF activation. Thus, according to the recent update of the consortium to inform molecular and practical approaches to central nervous system tumor taxonomy (cIMPACT‐NOW update 4), our case is also compatible with diffuse glioma with the mitogen‐activated protein kinase (MAPK) pathway alteration. Thorough immunohistochemical and molecular studies are necessary for diagnosis of epilepsy‐associated, diffuse gliomas. Partial resemblance in histopathological and molecular genetic features to diffuse astrocytoma also calls for attention. [ABSTRACT FROM AUTHOR]

Diffuse midline glioma, H3 K27M mutant arises from midline structures of the central nervous system and predominately affects pediatric patients. However, this disease entity was only recently established, and the clinical phenotypic spectrum remains largely unclear. We herein report a rare case of diffuse midline glioma, H3 K27M mutant with an unusual distribution in an elderly woman who presented with a diffuse glioma that invaded both sides of the thalami, and left hippocampus and frontoparietal lobes, thus mimicking a hemispheric malignant glioma. A biopsy of the lobular lesion led to a molecular diagnostic confirmation of diffuse midline glioma, H3 K27M mutant. The patient received concurrent bevacizumab and temozolomide therapy with radiation therapy and survived for 30 months. This case highlights the possibility that a glioma with cerebral hemispheric spread in an elderly patient may harbor the H3 K27M mutation. [ABSTRACT FROM AUTHOR]

The 2007 World Health Organization classification defined a new variant of glioblastoma ( GBM) containing oligodendroglioma foci as GBM with an oligodendroglioma component ( GBMO), which shows a favorable clinical outcome compared with 'classic' GBM. However, all of the reported cases of GBMO have been adult cases, with no previous reports of pediatric cases. In this report, we demonstrated molecular characteristics of a pediatric GBMO case, showing aggressive clinical behavior with 8-month overall survival. The case showed neither isocitrate dehydrogenase 1/2 genes ( IDH1/2) mutation nor 1p/19q co-deletion, a hallmark of oligodendroglioal tumors. In addition, microsatellite instability, leading to the putative mechanism of temozolomide ( TMZ) resistance, was frequently detected. Molecular genetic analysis may provide critical prognostic and therapeutic insights, especially for the pediatric glioma containing oligodendroglioma components. [ABSTRACT FROM AUTHOR]