CNS tumor with BCOR internal tandem duplication.

CNS tumor with BCOR internal tandem duplication is a recently proposed malignant tumor. The patient was an 18-month-old boy with torticollis and vomiting due to cerebellar hemispheric mass with extension to cerebellopontine angle and foramen magnum. Histopathologic examination of the tumor showed a moderately cellular tumor with microcystic formation, myxoid change, and atypical rosettes resembling Homer Wright rosettes. Illumina TruSight RNA Pan-Cancer NGS of the tumor genome revealed BCOR gene exon 15 internal tandem duplications.