Abstract
INTRODUCTION: BCOR, a transcriptional regulator and component of the noncanonical polycomb repressive complex 1 (PRC1), plays an important role in tumorigenesis through transcriptional repression mediated by histone modifications. Alterations in BCOR, including nonsense, frameshift, and splice site mutations, have been reported in several brain tumors such as glial tumors, astroblastomas, pineoblastomas, and medulloblastomas. However, BCOR alterations have not previously been described in IDH-mutant WHO grade 4 astrocytoma. CASE PRESENTATION: We describe an adult patient who presented with a recurrent, contrast-enhancing tumor in the left parietal region. The patient underwent complete surgical resection, and histopathology confirmed an IDH-mutant WHO grade 4 astrocytoma. Next-generation sequencing was performed using the TruSight Oncology 500 (TSO500) platform, including both DNA and RNA sequencing. Analysis revealed mutations in IDH1, ATRX, and EGFR, as well as a novel BCOR internal tandem duplication (ITD). CONCLUSION: This case represents the first report of a BCOR ITD in an IDH-mutant WHO grade 4 astrocytoma. The discovery expands the molecular spectrum of high-grade astrocytomas and highlights the need for further research into the biological, prognostic, and therapeutic significance of BCOR alterations in these tumors.