Giant invasive spinal schwannomas: definition and surgical management

Abstract

<jats:p content-type="fine-print"><jats:italic>Object.</jats:italic> Confusion exists regarding the term giant spinal schwannoma. There are a variety of nerve sheath tumors that, because of their size and extent, justify the label “giant schwannoma.” The authors propose a classification system for spinal schwannomas as a means to define these giant lesions. The classification is confined to tumors that are essentially intraspinal, with or without extraspinal components. Lesions that erode the vertebral bodies (VBs) and extend posteriorly and laterally into the myofascial planes are classified as giant “invasive” spinal schwannomas.</jats:p> <jats:p content-type="fine-print"><jats:italic>Methods.</jats:italic> The records of patients with giant invasive spinal schwannoma were analyzed. The radiological features, operative approaches, and intraoperative findings were noted.</jats:p> <jats:p content-type="fine-print">Ten patients with giant invasive tumors were surgically treated over the last 8 years. Six patients were male. Erosion of the posterior surface of the VBs was the diagnostic finding demonstrated on plain x-ray films. Magnetic resonance imaging delineated the extent of the tumors and helped in preoperative planning. Radical excision of the tumors in multiple stages was possible in eight of the 10 patients. Dural reconstruction was required in four patients. All patients required fusion, and an additional stabilization procedure was undertaken in three patients.</jats:p> <jats:p content-type="fine-print"><jats:italic>Conclusions.</jats:italic> The authors conclude that giant invasive schwannomas are uncommon lesions and propose a new classification system. Because of their locally “invasive” nature and extension in all directions, careful preoperative planning of the surgical approach is very important. Although radical excision is possible and promises good results, recurrences may occur and multiple surgical procedures may be required.</jats:p>

Giant solitary ancient schwannoma of the cervico-thoracic spine: a case report and review of the literature

“…Some surgeons do not routinely stabilise the spine following tumour removal. In a case series by Sridhar et al 1 , only two of 10 patients with giant schwannomas were stabilised following tumour removal. Their indication for stabilisation was erosion of more than 25% of the vertebral body.…”

“…Sridhar et al defined giant spinal schwannomas as those that extend over more than two vertebral levels 1 . Schwannomas are benign, slowgrowing, nerve sheath tumours that arise from neural, crest-derived Schwann cells along the dorsal sensory spinal roots, but occasionally, they may arise from the ventral motor roots.…”

Malignant Transformation of Benign Intraosseous Schwannoma in the Cervical Spine: A Case Report with an Immunohistochemical Study

“…2,23 Occasionally, schwannomas involve osseous structures. 7,24 The patients with giant invasive spinal schwannomas had erosion of the cervical vertebral body, and it extended posteriorly and laterally into myofascial planes (giant invasive tumors, type V) 9 or (Toyama classification, type VI). 25 A significant degree of aggressive, expansile, osteolytic lesions in the cervical spine and its accessory structure did occur.…”

“…4 The most common imaging findings of extradural spinal schwannomas involving bone include pedicle erosion, vertebral body scalloping, and widening of the neural foramen. 8 Based on the radiologic findings, Sridhar et al 9 proposed a classification system of spinal schwannomas as types I to V, in which type V of spinal schwannomas was defined as a giant invasive tumor in spinal intraosseous schwannomas. In a few patients the tumor presents as an expansile vertebral body lesion in the cervical spine, as reported in the literature.…”

“…In a few patients the tumor presents as an expansile vertebral body lesion in the cervical spine, as reported in the literature. 6,[9][10][11][12] Although primary malignant peripheral nerve sheath tumors (MPNSTs) of spine with or without the intraosseous involvement in association with von Recklinghausen's disease (neurofibromatosis type I) have been reported in the thoracic and lumbar spine, [12][13][14][15] malignant transformation of benign solitary schwannoma is extremely rare. 16,17 Woodruff et al 17 described 2 patients with such changes involving a finger and pelvis and reviewed 7 patients with malignant transformation.…”