OBJECTIVEIn this study, the authors sought to compare tumors with intradural extension to those remaining in the epidural or paraspinal space with the hypothesis that intradural extension may be a mechanism for seeding of the CSF with malignant cells, thereby resulting in higher rates of CNS metastases and shorter overall survival.METHODSThe authors searched the medical record for cases of malignant peripheral nerve sheath tumors (MPNSTs) identified from 1994 to 2017.