Successful Treatment of a CNS Tumor with BCOR Internal Tandem Duplication: A Case Report

A central nervous system (CNS) tumor with BCL-6 co-repressor (BCOR) internal tandem duplication (CNS tumor with BCOR ITD) is a rare tumor classified as an embryonal tumor by the World Health Organization classification (5th edition), and the prognosis is generally poor. A successfully treated case is reported, and its treatment is discussed. A five-year-old boy presented with a one-month history of headache and vomiting. Magnetic resonance imaging showed a well-demarcated, left-frontal tumor without perifocal edema. The patient underwent complete resection without a neurological deficit. Anti-BCOR antibody showed strong immunoreactivity in tumor nuclei, and the tumor was diagnosed as a CNS tumor with BCOR ITD. The patient received craniospinal irradiation (CSI) comprising 23.4 Gy, followed by a boost to the primary site to a total dose of 30.6 Gy in daily fractions of 1.8 Gy. The chemotherapy comprised four cycles of vincristine, cyclophosphamide, and cisplatin with peripheral blood stem cell rescue. The clinical course was uneventful throughout the treatment, the tumor has not recurred for four years, and no neurological impairment was reported. CSI and multiagent chemotherapy were effective for a CNS tumor with BCOR ITD.