While inactivating mutations involving CDKN2A/B are rare in MPNST, they have been associated with similar poor clinical outcomes in other tumor types where CDKN2A/B status is incorporated into current grading schemes.46 Importantly, we propose heterozygous or subclonal CDKN2A/B inactivation (through copy number loss or mutation) in isolation would be insufficient for an integrated diagnosis of ANNUBP. This evidence concerns the gene CDKN2A and malignant peripheral nerve sheath tumor.