Although gliomatosis cerebri (GC) has been removed as an independent tumor type from the WHO classification, its extensive infiltrative pattern may harbor a unique biological behavior. However, the clinical implication of GC in the context of the 2021 WHO classification is yet to be unveiled. This study investigated the incidence, clinicopathologic and imaging correlations, and prognostic implications of GC in adult-type diffuse glioma patients. Retrospective chart and imaging review of 1,211 adult-type diffuse glioma patients from a single institution between 2005 and 2021 was performed. Among 1,211 adult-type diffuse glioma patients, there were 99 (8.2%) patients with GC. The proportion of molecular types significantly differed between patients with and without GC (P = 0.017); IDH-wildtype glioblastoma was more common (77.8% vs. 66.5%), while IDH-mutant astrocytoma (16.2% vs. 16.9%) and oligodendroglioma (6.1% vs. 16.5%) were less common in patients with GC than in those without GC. The presence of contrast enhancement, necrosis, cystic change, hemorrhage, and GC type 2 were independent risk factors for predicting IDH mutation status in GC patients. GC remained as an independent prognostic factor (HR = 1.25, P = 0.031) in IDH-wildtype glioblastoma patients on multivariable analysis, along with clinical, molecular, and surgical factors. Overall, our data suggests that although no longer included as a distinct pathological entity in the WHO classification, recognition of GC may be crucial considering its clinical significance. There is a relatively high incidence of GC in adult-type diffuse gliomas, with different proportion according to molecular types between patients with and without GC. Imaging may preoperatively predict the molecular type in GC patients and may assist clinical decision-making. The prognostic role of GC promotes its recognition in clinical settings.

In the most recent fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System, astroblastoma has been defined by molecular rearrangements involving the MN1 gene, with common partners being BEND2 or CXXC5 . Accordingly, this tumor entity is now known as \"astroblastoma, MN1 -altered.\" However, gliomas with EWSR1::BEND2 fusions, devoid of MN1 fusion alterations, have recently been shown to exhibit astroblastoma-like histomorphologic features and reside in a distinct epigenetic subgroup based on DNA methylation studies similar to high-grade neuroepithelial tumor with MN1 alteration, which includes astroblastoma, MN1 altered tumors. This new epigenetically distinct subtype of astroblastoma containing EWSR1::BEND2 fusions lacks the required MN1 alteration and, thus, does not satisfy the current molecular classification of these lesions. Here, we describe a case of glioma with histologic features and DNA methylation profiling consistent with astroblastoma with a novel YAP1: : BEND2 fusion. This case and others further expand the molecular findings observable in astroblastoma-like tumors outside the constraints of MN1 alteration. Such cases of astroblastoma with EWSR1::BEND2 and YAP1::BEND2 fusions challenge the current molecular classification of astroblastoma based solely on an MN1 alteration.

We report the novel clinical presentation of a primary brain neoplasm in a 30-year-old man with a mass-like area in the anteromedial temporal lobe. Histopathological analysis revealed a low-grade neuroepithelial tumor with cytologically abnormal neurons and atypical glial cells within the cerebral cortex. Molecular analysis showed a previously undescribed FGFR2::DLG5 rearrangement. We discuss the clinical significance and molecular implications of this fusion event, shedding light on its potential impact on tumor development and patient prognosis. Additionally, an extensive review places the finding in this case in the context of protein fusions in brain tumors in general and highlights their diverse manifestations, underlying molecular mechanisms, and therapeutic implications.

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BACKGROUND: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a rare entity of low-grade neuroepithelial tumors that primarily affects children and young adults. This distinct type of tumor presents unique challenges in diagnosis and management. With its relatively recent identification, researchers and clinicians are striving to understand the characteristics, behavior, and optimal treatment strategies. The symptoms are primarily related to seizures. However, PLNTY can be asymptomatic in some cases.
METHODS: This is a single-center case report study and a literature review paper. We reviewed a case treated and diagnosed at the Ankara University Faculty of Medicine, Department of Neurosurgery. The demographic data, clinical follow-ups, laboratory, and radiological data of the patients were assessed.
RESULTS: We present a 32-year-old male patient who has undergone gross total surgical excision with strict clinical follow-up. Clinical course as well as surgical data of the patient were observed and analyzed.
CONCLUSIONS: On imaging, morphologic resembling and indistinctive clinical course can be nonspecific, contributing to diagnostic uncertainties. This case report was written with the notion that rare diagnoses present an opportunity to understand the progression and patho-oncological factors that can pave the way for better treatment.

OBJECTIVE: This study aimed to evaluate epilepsy outcome and antiseizure medication (ASM) discontinuation after lesionectomies as first surgical approach in pediatric population diagnosed with low-grade epilepsy-associated neuroepithelial tumors (LEATs).
METHODS: We conducted a retrospective study. Thirty-six consecutive patients with histological diagnoses of LEATs who underwent surgery between 2018 and 2021 at our institution were included. The clinical and surgical data were retrospectively analyzed.
RESULTS: Thirty (83.3%) of 36 patients are free of disabling seizures (Engel class I) and 19 (63,4%) of them are classified as Engel Ia. In 17 (47.2%) patients, ASM could be discontinued. The mean age at surgery was 8.6 years (±4.04) and the mean age at onset of epilepsy was 7.2 years (±3.8), whereas the mean duration of epilepsy in months at the time of surgery was 21.3 months (±23.7). The epileptogenic tumor was in the temporal lobe in 20 (55.5%) patients. Because of seizure persistence, a second or a third surgery was necessary for six patients (16.7%) and four of them had residual lesions (three in temporal and one in extratemporal site). No perioperative complications were recorded, including acute seizures, with a median hospitalization time of 7 days. Shorter epilepsy duration at time of surgery as long as a single ASM was significantly correlated with an Engel class I outcome (p-value = .01 and p-value = .016, respectively). Focal seizure semeiology was associated with an increased probability of antiseizure medication discontinuation (p-value = .042).
CONCLUSIONS: Our findings confirm that shorter epilepsy disease duration, monotherapy before surgery, and seizure semeiology are determinant factors for a positive seizure outcome and medication discontinuation, also with less invasive surgical approaches such as lesionectomies. However, considering the intrinsic multifactorial epileptogenic nature of LEATs, a tailored surgical approach should be considered to optimize clinical and seizure outcome, especially for lesions located in the temporal lobe.

OBJECTIVE: There is lack of comprehensive analysis evaluating the impact of clinical, molecular, imaging, and surgical data on survival of patients with gliomatosis cerebri (GC). This study aimed to investigate prognostic factors of GC in adult-type diffuse glioma patients.
METHODS: Retrospective chart and imaging review was performed in 99 GC patients from adult-type diffuse glioma (among 1,211 patients; 6 oligodendroglioma, 16 IDH-mutant astrocytoma, and 77 IDH-wildtype glioblastoma) from a single institution between 2005 and 2021. Predictors of overall survival (OS) of entire patients and IDH-wildtype glioblastoma patients were determined.
RESULTS: The median OS was 16.7 months (95% confidence interval [CI] 14.2-22.2) in entire patients and 14.3 months (95% CI 12.2-61.9) in IDH-wildtype glioblastoma patients. In entire patients, KPS (hazard ratio [HR] = 0.98, P = 0.004), no 1p/19q codeletion (HR = 10.75, P = 0.019), MGMTp methylation (HR = 0.54, P = 0.028), and hemorrhage (HR = 3.45, P = 0.001) were independent prognostic factors on multivariable analysis. In IDH-wildtype glioblastoma patients, KPS (HR = 2.24, P = 0.075) was the only independent prognostic factor on multivariable analysis. In subgroup of IDH-wildtype glioblastoma with CE tumors, total resection of CE tumor did not remain as a significant prognostic factor (HR = 1.13, P = 0.685).
CONCLUSIONS: The prognosis of GC patients is determined by its underlying molecular type and patient performance status. Compared with diffuse glioma without GC, aggressive surgery of CE tumor in GC patients does not improve survival.

Methylation class \"CNS tumor with BCOR/BCOR(L1)-fusion\" was recently defined based on methylation profiling and tSNE analysis of a series of 21 neuroepithelial tumors with predominant presence of a BCOR fusion and/or characteristic CNV breakpoints at chromosome 22q12.31 and chromosome Xp11.4. Clear diagnostic criteria are still missing for this tumor type, specially that BCOR/BCOR(L1)-fusion is not a consistent finding in these tumors despite being frequent and that none of the Heidelberger classifier versions is able to clearly identify these cases, in particular tumors with alternative fusions other than those involving BCOR, BCORL1, EP300 and CREBBP. In this study, we introduce a BCOR::CREBBP fusion in an adult patient with a right temporomediobasal tumor, for the first time in association with methylation class \"CNS tumor with BCOR/BCOR(L1)-fusion\" in addition to 35 cases of CNS neuroepithelial tumors with molecular and histopathological characteristics compatible with \"CNS tumor with BCOR/BCOR(L1)-fusion\" based on a comprehensive literature review and data mining in the repository of 23 published studies on neuroepithelial brain Tumors including 7207 samples of 6761 patients. Based on our index case and the 35 cases found in the literature, we suggest the archetypical histological and molecular features of \"CNS tumor with BCOR/BCOR(L1)-fusion\". We also present four adult diffuse glioma cases including GBM, IDH-Wildtype and Astrocytoma, IDH-Mutant with CREBBP fusions and describe the necessity of complementary molecular analysis in \"CNS tumor with BCOR/BCOR(L1)-alterations for securing a final diagnosis.

Molecular biomarker identification increasingly influences the treatment planning of pediatric low-grade neuroepithelial tumors (PLGNTs). We aimed to develop and validate a radiomics-based ADC signature predictive of the molecular status of PLGNTs.
In this retrospective bi-institutional study, we searched the PACS for baseline brain MRIs from children with PLGNTs. Semiautomated tumor segmentation on ADC maps was performed using the semiautomated level tracing effect tool with 3D Slicer. Clinical variables, including age, sex, and tumor location, were collected from chart review. The molecular status of tumors was derived from biopsy. Multiclass random forests were used to predict the molecular status and fine-tuned using a grid search on the validation sets. Models were evaluated using independent and unseen test sets based on the combined data, and the area under the receiver operating characteristic curve (AUC) was calculated for the prediction of 3 classes: KIAA1549-BRAF fusion, BRAF V600E mutation, and non-BRAF cohorts. Experiments were repeated 100 times using different random data splits and model initializations to ensure reproducible results.
Two hundred ninety-nine children from the first institution and 23 children from the second institution were included (53.6% male; mean, age 8.01 years; 51.8% supratentorial; 52.2% with KIAA1549-BRAF fusion). For the 3-class prediction using radiomics features only, the average test AUC was 0.74 (95% CI, 0.73-0.75), and using clinical features only, the average test AUC was 0.67 (95% CI, 0.66-0.68). The combination of both radiomics and clinical features improved the AUC to 0.77 (95% CI, 0.75-0.77). The diagnostic performance of the per-class test AUC was higher in identifying KIAA1549-BRAF fusion tumors among the other subgroups (AUC = 0.81 for the combined radiomics and clinical features versus 0.75 and 0.74 for BRAF V600E mutation and non-BRAF, respectively).
ADC values of tumor segmentations have differentiative signals that can be used for training machine learning classifiers for molecular biomarker identification of PLGNTs. ADC-based pretherapeutic differentiation of the BRAF status of PLGNTs has the potential to avoid invasive tumor biopsy and enable earlier initiation of targeted therapy.

BACKGROUND: Methylation analysis has become a powerful diagnostic tool in modern neurooncology. This technique is valuable to diagnose new brain tumor types.
OBJECTIVE: To describe the MRI and histological pattern of neuroepithelial tumor with PLAGL1 gene fusion.
METHODS: We present a 6-year-old patient with small right frontal intraaxial tumor causing drug resistant epilepsy. Despite indolent preoperative clinical course and MRI features suggesting glioneuronal tumor, histological evaluation revealed characteristics of high-grade glioma, ependymoma and neuroblastoma.
RESULTS: Methylation analysis of tumor DNA confirmed a new type of a recently discovered neoplasm - neuroepithelial tumor with PLAGL1 fusion (NET PLAGL1). PCR confirmed fusion of PLAGL1 and EWSR1 genes. No seizures were observed throughout the follow-up period. There was no tumor relapse a year after surgery.
CONCLUSIONS: Methylation analysis in neurooncology is essential for unclear tumor morphology or divergence between histological and clinical data. In our case, this technique confirmed benign nature of tumor, and we preferred follow-up without unnecessary adjuvant treatment.
Определение метиляционного профиля генома опухоли становится значимым способом диагностики новообразований центральной нервной системы. На основании этой методики также возможно выявлять новые классы опухолей головного мозга.
UNASSIGNED: Описать результаты магнитно-резонансной томографии (МРТ) и гистологическую картину нейроэпителиальной опухоли со слиянием гена PLAGL1.
UNASSIGNED: Представлено клиническое наблюдение ребенка 6 лет с внутримозговой опухолью лобной доли и фармакорезистентной эпилепсией. По рентгенологическим характеристикам, до операции предполагалась доброкачественная глионейрональная опухоль, однако гистология соответствовала новообразованию, имевшему черты злокачественной глиомы, эпендимомы и нейробластомы.
UNASSIGNED: Проведен метиляционный анализ ткани опухоли, показавший, что она относится к недавно описанному новому классу — «нейроэпителиальная опухоль со слиянием гена PLAGL1». Тест полимеразной цепной реакции подтвердил слияние генов PLAGL1 и EWSR1. После операции отмечено прекращение приступов, спустя 1 год на МРТ рецидива опухоли не определялось.
UNASSIGNED: Метиляционный анализ в нейроонкологии играет решающую роль в случаях неоднозначной морфологии опухоли, расхождения ее гистологической и клинико-рентгенологической картины. В приведенном клиническом примере стало возможным доказать доброкачественный характер опухоли и выбрать выжидательную тактику, избежав адъювантного лечения у ребенка.