CLINICAL ARTICLE J Neurosurg 128:1226–1234, 2018 P eriPheral nerve tumors may be of neuroectodermal origin, derived from the neural sheath, or of non- neural sheath origin. Benign peripheral nerve sheath tumors (BPNSTs) include neurofbromas and schwanno- mas, which collectively constitute 10%–12% of benign soft-tissue neoplasms. 19,28,29 Malignant PNSTs (MPNSTs) represent 5%–10% of all soft-tissue sarcomas and occur in 0.001% of the general population. 12,30 Both BPNSTs and MPNSTs may occur sporadically, or in association with autosomal dominant neurofbromato- ses (NFs). Sixty percent of patients with neurofbromatosis Type 1 (NF1)—the most common NF—will develop soli- tary, diffuse, or plexiform benign neurofbromas, the latter two occurring almost exclusively in patients with NF1. 11,26 NF1-associated neurofbromas have an estimated 10%– 15% risk of malignant transformation, with internal plexi- form tumors at the highest risk of conversion. 32 MPNSTs occur in up to 10% of NF1 patients over their lifetimes; conversely, half of all MPNSTs are seen in NF1 patients. 5 Peripheral schwannomas are typically sporadic, although ABBREVIATIONS BPNST = benign peripheral nerve sheath tumor; GTR = gross-total resection; MPNST = malignant peripheral nerve sheath tumor; NF = neurofibromato- sis; NF1, NF2, NF3 = NF Type 1, Type 2, Type 3; PNST = peripheral nerve sheath tumor; STR = subtotal resection. SUBMITTED August 31, 2016. ACCEPTED January 26, 2017. INCLUDE WHEN CITING Published online July 7, 2017; DOI: 10.3171/2017.1.JNS162292. Management of peripheral nerve sheath tumors: 17 years of experience at Toronto Western Hospital Daipayan Guha, MD, 1 Benjamin Davidson, MD, 1 Mustafa Nadi, MD, 1 Naif M. Alotaibi, MD, 1 Michael G. Fehlings, MD, PhD, FRCSC, 1,2 Fred Gentili, MD, MSc, 1,2 Taufk A. Valiante, MD, PhD, 1,2 Charles H. Tator, MD, PhD, 1,2 Michael Tymianski, MD, PhD, 1,2 Abhijit Guha, MD, MSc, 1,2 and Gelareh Zadeh, MD, PhD 1,2 1 Department of Surgery, University of Toronto; and 2 Division of Neurosurgery, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada OBJECTIVE A surgical series of 201 benign and malignant peripheral nerve sheath tumors (PNSTs) was assessed to characterize the anatomical and clinical presentation of tumors and identify predictors of neurological outcome, recur- rence, and extent of resection. METHODS All surgically treated PNSTs from the Division of Neurosurgery at Toronto Western Hospital from 1993 to 2010 were reviewed retrospectively. Data were collected on patient demographics, clinical presentation, surgical tech- nique, extent of resection, postoperative neurological outcomes, and recurrence. RESULTS One hundred seventy-fve patients with 201 tumors had adequate follow-up for analysis. There were 182 benign and 19 malignant PNSTs. Of the benign lesions, 133 were schwannomas, 21 of which were associated with a diagnosis of schwannomatosis. There were 49 neurofbromas, and 26 were associated with neurofbromatosis Type 1 (NF1). Patients presenting with schwannomas were signifcantly older than those with neurofbromas. Schwannomas were more readily resected than neurofbromas, with the extent of resection of the former infuenced by tumor location. Patients with benign PNSTs typically presented with a painful mass and less frequently with motor defcits. The likelihood of worsened postoperative motor function was decreased in patients with fully resected tumors or preoperative defcits. Recurrence of schwannomas and neurofbromas were seen more frequently in patients diagnosed with NF3 and NF1, respectively. Subtotal resection was associated with the increased recurrence of all benign lesions. CONCLUSIONS Outcomes following resection of benign PNSTs depend on tumor histopathology, tumor location, and genetic predisposition syndrome. Gross-total resection should be attempted for benign lesions where possible. The management of malignant PNSTs remains challenging, requiring a multimodal approach. https://thejns.org/doi/abs/10.3171/2017.1.JNS162292 KEY WORDS peripheral nerve; schwannoma; neurofibroma; MPNST; tumor J Neurosurg Volume 128 • April 2018 1226 ©AANS 2018, except where prohibited by US copyright law Unauthenticated | Downloaded 05/17/22 07:06 AM UTC