A Central Nervous System Tumor with BCOR Internal Tandem Duplication: Case Report of a Distinct Molecular Pediatric Entity

Central nervous system (CNS) tumors with BCOR internal tandem duplication (ITD) are a rare, recently defined entity of pediatric neuroepithelial neoplams. These tumors frequently pose diagnostic challenges because of overlapping histological and radiological features with other high-grade CNS tumors. We report a case of 4-year-old male who presented with a right frontal space-occupying lesion following a history of a sudden fall. Imaging initially suggested a intraparenchymal and subdural hemorrhage. The patient underwent emergency craniotomy and debulking. Histopathology revealed a hypercellular tumor with solid growth pattern, a dense capillary network, perivascular pseudorosettes, and brisk mitotic activity. Immunohistochemistry was negative for IDH1R132H, OLIG-2 (oligodendrocyte transcription factor 2), EMA (epithelial membrane antigen), P53, G34R-V, H3K27M, and H3K27me3, while ATRX was retained, initially interpreted as a diffuse pediatric-type high-grade glioma, not otherwise specified, World Health Organization grade 4. Subsequent deoxyribonucleic acid methylation profiling identified a CNS tumor with BCOR ITD, clustering with neuroepithelial tumors. The patient received craniospinal irradiation with a local boost and concurrent temozolomide per institutional multidisciplinary decision but showed radiological progression following treatment and died 25 months after diagnosis. This case highlights the diagnostic value of integrated molecular profiling in identifying CNS BCOR ITD tumors, and challenges in management and decision-making in emergency presentations and resource-limited settings. We discuss diagnostic workflow, treatment rationale, and utility of surrogate markers such as BCOR immunohistochemistry in this rare pediatric tumor.