VGLL-fusions define a new class of intraparenchymal CNS schwannoma

This study is important as it identifies and characterizes a new class of benign CNS tumors, termed VGLL-altered intraparenchymal CNS schwannomas. These rare tumors, previously unclassified, resemble schwannomas but are found within CNS tissue. By analyzing 20 tumor samples using advanced molecular and histological techniques, the study reveals that these tumors have a distinct DNA methylation profile and frequently harbor VGLL3 or VGLL1 gene fusions. The findings offer a clearer understanding of their morphology, molecular characteristics, and behavior, with MRI showing well-defined, nodular tumors and clinical data indicating no recurrence during follow-up. This research enhances diagnostic accuracy and may inform treatment strategies for these rare intracerebral neoplasms, highlighting the need for their recognition as a separate tumor type in medical classifications. We analyzed 20 tumor samples by histology, targeted RNA Next-Generation Sequencing, DNA-methylation profiling (Illumina 450k and 850k Beadchips), copy number analyses, and single nucleus RNA sequencing. Clinical data, including age, sex, and disease progression, were collected. Presurgical MRI series were included when available.