The implications of intradural extension in paraspinal malignant peripheral nerve sheath tumors: effects on central nervous system metastases and overall survival

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In 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.


The authors searched the medical record for cases of malignant peripheral nerve sheath tumors (MPNSTs) identified from 1994 to 2017. The charts of the identified patients were then reviewed for tumor location to identify patients with paraspinal malignancy. All patients included in the study had tumor specimens that were reviewed in the surgical pathology department. Paraspinal tumors with intradural extension were identified in the lumbar, sacral, and spinal accessory nerves, and attempts were made to match this cohort to another cohort of patients who had paraspinal tumors of the cranial nerves and lumbar and sacral spinal regions without intradural extension. Further information was collected on all patients with and without intradural extension, including date of diagnosis by pathology specimen review; nerve or nerves of tumor origin; presence, location, and diagnostic date of any CNS metastases; and either the date of death or date of last follow-up.


The authors identified 6 of 179 (3.4%) patients who had intradural tumor extension and compared these patients with 12 patients who harbored paraspinal tumors that did not have intradural extension. All tumors were diagnosed as high-grade MPNSTs according to the surgical pathology findings. Four of 6 (66.7%) patients with intradural extension had documented CNS metastases. The presence of CNS metastases was significantly higher in the intradural group than in the paraspinal group (intradural, 66.7% vs paraspinal, 0%; p < 0.01). Time from diagnosis until death was 11.2 months in the intradural group and approximately 72 months in the paraspinal, extradural cohort.


In patients with intradural extension of paraspinal MPNSTs, significantly higher rates of CNS metastases are seen with a reduced interval of time from diagnosis to metastatic lesion detection. Intradural tumor extension is also a poor prognostic factor for survival, with these patients showing a reduced mean time from diagnosis to death.

ABBREVIATIONS DSS = disease-specific survival; MPNST = malignant peripheral nerve sheath tumor.

Article Information

Correspondence Robert J. Spinner: Mayo Clinic, Rochester, MN.

INCLUDE WHEN CITING Published online September 21, 2018; DOI: 10.3171/2018.5.SPINE18445.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.



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    A: Axial T2-weighted MR image of the lumbar spine in a patient with a right L5 MPNST. The tumor mass is apparent within the CSF space, suggesting intradural invasion. B: Axial T2-weighted MR image obtained in a patient with a left S1 MPNST in the epidural and paraspinal space without intradural extension.

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    Kaplan-Meier survival curves for patients with paraspinal MPNSTs with and without intradural extension.





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