Central Nervous System Tumor With BCL6 Corepressor Internal Tandem Duplication: Treatment Course of a Long-term Survivor.

Central nervous system (CNS) tumor with BCL6 corepressor (BCOR) internal tandem duplication (ITD) is a newly described CNS tumor, characterized by in-frame ITDs of the BCOR gene. There is no standard practice regarding the management of this tumor. We report the clinical course of a 6-year-old boy who presented to the hospital with worsening headaches. Computed tomography scan showed a large right-sided parietal supratentorial mass and brain magnetic resonance imaging confirmed a 6×8×6.7 cm lobulated, solid but heterogeneous mass in the right parieto-occipital region. While initial pathology suggested a WHO grade 3 anaplastic meningioma, additional investigation with molecular analysis confirmed the diagnosis of high-grade neuroepithelial tumor with BCOR exon 15 ITD. This diagnosis was renamed CNS tumor with BCOR ITD in the 2021 WHO CNS tumor classification. The patient received 54 Gy of focal radiation and has no evidence of disease recurrence after 48 months from the end of treatment. As this is a newly discovered entity with only a few previous reports in the scientific literature, this report presents a unique treatment for this CNS tumor compared with those previously described.