The 2021 WHO Classification of Tumors of the Central Nervous System, 5th edition (WHO CNS5), introduced revised diagnostic criteria for pediatric brain tumors (BTs), redefining pediatric-type diffuse high-grade gliomas (pHGGs) into 4 subtypes: diffuse midline glioma, H3 K27-altered (DMG-H3K27), diffuse hemispheric glioma, H3 G34-mutant (DHG-H3G34), diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype (DpHGG-H3wt/IDHwt), and infant-type hemispheric glioma (IHG). This study revisits prior diagnoses of HGGs and primitive neuroectodermal tumors (PNETs) in children and incorporates next-generation sequencing (NGS) to classify tumors according to the revised criteria and analyze their clinicogenomic characteristics and outcomes. A retrospective review of pediatric patients diagnosed with glioblastoma (GBM), anaplastic astrocytoma, anaplastic oligoastrocytoma (AOA), gliomatosis cerebri, or PNET between 1997 and 2023 was conducted. Cases underwent pathology review, immunohistochemistry (IHC), and BT-targeted NGS for reclassification per WHO CNS5. An additional 20 patients diagnosed with pHGG via genetics-integrated diagnosis since 2020 were included. Clinical characteristics, genomic alterations, and outcomes were analyzed. Among the 78 reviewed cases, 41 were reclassified as pHGGs. TP53 mutations were the most prevalent, particularly in DpHGG-H3wt/IDHwt, which showed associations with cancer predisposition syndrome (CPS). Two patients with Li-Fraumeni syndrome (LFS) developed DpHGG-H3wt/IDHwt adjacent to prior radiation fields. The 2-year overall survival (OS) rates were lowest in DpHGG-H3wt/IDHwt (23.2%) and highest in IHG (92.3%). Long-term survival was observed in IHG patients, with a 5-year OS rate of 73.8%, indicating the need for different adjuvant treatment strategies compared to other pHGGs. BT-targeted NGS facilitates the reclassification of pHGGs, revealing associations with CPS. Routine germline sequencing is warranted, and accurate molecular diagnosis enables a shift in treatment strategies tailored to specific pHGG subtypes.

Outcomes of recurrent paediatric high-grade glioma are poor, with a median overall survival of less than 6 months. Viral immunotherapy, such as the polio-rhinovirus chimera lerapolturev, is a novel approach for treatment of recurrent paediatric high-grade glioma and has shown promise in adults with recurrent glioblastoma. The poliovirus receptor CD155 is ubiquitously expressed in malignant paediatric brain tumours and is a treatment target in paediatric high-grade glioma. We aimed to assess the safety of lerapolturev when administered as a single dose intracerebrally by convection enhanced delivery in children and young people with recurrent WHO grade 3 or grade 4 glioma, and to assess overall survival in these patients. This phase 1b trial was done at the Duke University Medical Center (Durham, NC, USA). Patients aged 4-21 years with recurrent high-grade malignant glioma (anaplastic astrocytoma, glioblastoma, anaplastic oligoastrocytoma, anaplastic oligodendroglioma, or anaplastic pleomorphic xanthoastrocytoma) or anaplastic ependymoma, atypical teratoid rhabdoid tumour, or medulloblastoma with infusible disease were eligible for this study. A catheter was tunnelled beneath the scalp for a distance of at least 5 cm to aid in prevention of infection. The next day, lerapolturev at a dose of 5 × 107 median tissue culture infectious dose in 3 mL infusate loaded in a syringe was administered via a pump at a rate of 0·5 mL per h as a one-time dose. The infusion time was approximately 6·5 h to compensate for volume of the tubing. The primary endpoint was the proportion of patients with unacceptable toxic effects during the 14-day period after lerapolturev treatment. The study is registered with ClinicalTrials.gov, NCT03043391. Between Dec 5, 2017, and May 12, 2021, 12 patients (11 unique patients) were enrolled in the trial. Eight patients were treated with lerapolturev. The median patient age was 16·5 years (IQR 11·0-18·0), five (63%) of eight patients were male and three (38%) were female, and six (75%) of eight patients were White and two (25%) were Black or African American. The median number of previous chemotherapeutic regimens was 3·50 (IQR 1·25-5·00). Six of eight patients had 26 treatment-related adverse events attributable to lerapolturev. There were no irreversible (ie, persisted longer than 2 weeks) treatment-related grade 4 adverse events or deaths. Treatment-related grade 3 adverse events included headaches in two patients and seizure in one patient. Four patients received low-dose bevacizumab on-study for treatment-related peritumoural inflammation or oedema, diagnosed by both clinical symptoms plus fluid-attenuated inversion recovery MRI. The median overall survival was 4·1 months (95% CI 1·2-10·1). One patient remains alive after 22 months. Convection enhanced delivery of lerapolturev is safe enough in the treatment of recurrent paediatric high-grade glioma to proceed to the next phase of trial. Solving Kids Cancer, B+ Foundation, Musella Foundation, and National Institutes of Health.

We describe the clinical and pathological features of a brain collision tumour consisting of a fibrous meningioma and an anaplastic oligoastrocytoma in a 14-year-old male neutered French Bulldog. Computed tomography of the brain revealed a poorly defined, intra-axial lesion affecting the left frontal lobe. Following euthanasia, histological examination showed an anaplastic oligoastrocytoma invading the brain parenchyma and an adjacent fibrous meningioma. As synchronous intracranial tumours are rare in animals, the aims of this report are to describe the clinical, imaging and histopathological features of an intracranial collision tumour in a dog and highlight the importance of a complete histopathological study despite the imaging findings.

Isocitrate dehydrogenase (IDH) mutations are cornerstone diagnostic features in glioma classification. IDH mutations are typically characterized by mutually exclusive amino acid substitutions in the genes encoding for the IDH1 and the IDH2 enzyme isoforms. We report our institutional case of a diffuse astrocytoma with progression to secondary glioblastoma and concurrent IDH1/IDH2 mutations. A 49-year-old male underwent a subtotal resection of a lobular lesion within the right insula in 2013, revealing a WHO grade 3 anaplastic oligoastrocytoma, IDH1 mutated, 1p19q intact. Symptomatic tumor progression was suspected in 2018, leading to a surgical tumor biopsy that demonstrated WHO grade 4 IDH1 and IDH2 mutant diffuse astrocytoma. The patient subsequently underwent surgical resection followed by medical management and finally died in 2021. Although concurrent IDH1/IDH2 mutations have been rarely reported in the current literature, further study is required to better define their impact on patients' prognoses and their response to targeted therapies.

The revised fourth edition of the World Health Organization classification of central nervous system tumors was published in 2016. Based on this classification, one of the infiltrating glioma entities named "oligoastrocytoma/anaplastic oligoastrocytoma" is discouraged. It is proposed that these mixed gliomas should be classified as diffuse astrocytoma/anaplastic astrocytoma or oligodendroglioma/anaplastic oligodendroglioma when analyzing their genetic alteration. A 78-year-old female underwent brain computed tomography (CT) because of a traffic accident. Cranial CT revealed a brain tumor in the left temporoparietal lobe; therefore, she was hospitalized. She underwent awake craniotomy. After the operation, she was treated with only local radiotherapy; the authors could not prescribe temozolomide, because she had had levetiracetam-induced pancytopenia. The remaining tumor neuroradiologically disappeared, and she was alive 40 months after the operation without tumor recurrence. Histopathologically, this tumor was diagnosed as an anaplastic oligoastrocytoma with a distinct dual phenotype of astrocytoma and oligodendroglioma components. Genetically, these two components revealed astrocytoma and oligodendroglioma genotypes, respectively. Therefore, the authors considered the integrated diagnosis of the temporal tumor as a true anaplastic oligoastrocytoma with a dual genotype. Interestingly, this case also included an area composed of spindle to oval neoplastic cells that revealed intermediate genetic alterations between astrocytomas and oligodendrogliomas.