CNS tumor with EP300::BCOR fusion: discussing its prevalence in adult population

The Central Nervous System (CNS) tumor with BCOR internal tandem duplication (ITD) has recently been added as a novel embryonal histomolecular tumor type to the 2021 World Health Organization (WHO) Classification of CNS Tumors. In addition, other CNS tumors harboring a BCOR/BCORL1 fusion, which are defined by a distinct DNA-methylation profile, have been recently identified in the literature but clinical, radiological and histopathological data remain scarce. Herein, we present two adult cases of CNS tumors with EP300::BCOR fusion. These two cases presented radiological, histopathological, and immunohistochemical homologies with CNS tumors having BCOR ITD in children. To compare these tumors with different BCOR alterations, we performed a literature review with a meta-analysis. CNS tumors with EP300::BCOR fusion seem to be distinct from their BCOR ITD counterparts in terms of age, location, progression-free survival, tumor growth pattern, and immunopositivity for the BCOR protein. CNS tumors from the EP300::BCOR fusion methylation class in adults may be added to the future WHO classification.

Automated summary

The Central Nervous System (CNS) tumor with BCOR internal tandem duplication (ITD) has been recognized as a novel embryonal histomolecular tumor type in the 2021 World Health Organization (WHO) Classification of CNS Tumors. Meanwhile, CNS tumors harboring a BCOR/BCORL1 fusion, characterized by a distinct DNA-methylation profile, have also been identified in recent literature. This study presents two adult cases of CNS tumors with EP300::BCOR fusion, which share similarities with CNS tumors having BCOR ITD in children. A literature review and meta-analysis indicate that CNS tumors with EP300::BCOR fusion are distinguishable from BCOR ITD tumors in terms of age, location, progression-free survival, tumor growth pattern, and immunopositivity for the BCOR protein. Thus, CNS tumors with EP300::BCOR fusion in adults may be included in future WHO classification.