Abstract The Consortium to Inform Molecular and Practical Approaches to Central Nervous System Tumor Taxonomy (cIMPACT‐NOW) updates provide guidelines for the diagnosis of central nervous system (CNS) tumors and suggestions for future World Health Organization (WHO) classification. Following publication of the fifth edition WHO Classification of CNS Tumors (WHO CNS5) in 2021, the cIMPACT‐NOW working group “Clarification” reviewed WHO CNS5 and prioritized two topics for further elucidation: (a) distinction of Gliob…

Abstract DNA methylation-based classification is integral to contemporary neuro-oncological diagnostics, as highlighted by the current World Health Organization (WHO) classification of central nervous system (CNS) tumors. We introduce the Heidelberg CNS Tumor Methylation Classifier version 12.8 (v12.8), trained using 7,495 methylation profiles, thereby expanding recognized tumor types from 91 classes in the previously published v11 1 to 184 subclasses in v12.8. This expansion was primarily driven by novel tumor ty…

Abstract Background Isocitrate dehydrogenase (IDH)-mutant astrocytomas represent the most frequent primary intraparenchymal brain tumor in young adults, which typically arise as low-grade neoplasms that often progress and transform to higher grade despite current therapeutic approaches. However, the genetic alterations underlying high-grade transformation and disease progression of IDH-mutant astrocytomas remain inadequately defined. Methods Genomic profiling was performed on 205 IDH-mutant astrocytomas from 172 p…

Low-grade gliomas and reactive piloid gliosis can present with overlapping features on conventional histology. Given the large implications for patient treatment, there is a need for effective methods to discriminate these morphologically similar but clinically distinct entities. Using routinely available stains, we hypothesize that a limited panel including SOX10, p16, and cyclin D1 may be useful in differentiating mitogen-activated protein (MAP) kinase-activated low-grade gliomas from piloid gliosis. Reviewers b…

Abstract The care of patients with meningioma is often multidisciplinary due to potential tumor and treatment morbidity, evolving biomarkers, high rates of recurrence in select subgroups, and emerging systemic therapies. UCSF previously convened two tumor boards for adult brain tumor patients, one general (median 14 patients/week, range 4-25) and one specific for stereotactic radiosurgery (median 13 patients/week, range 5-28). Due to patient volume, a separate meningioma multidisciplinary tumor board (MMTB) and me…