Malignant peripheral nerve sheath tumours of the spine: clinical manifestations, classification, treatment, and prognostic factors

Abstract

Background and objectives: To summarise our experience treating patients with spinal malignant peripheral nerve sheath tumours (MPNSTs).

Methods: We retrospectively reviewed the records of patients diagnosed with spinal MPNSTs who received surgical treatment from January 1998 to December 2009.

Results: Postoperative follow-up data were available for 14/16 patients with spinal MPNSTs (7 men, 7 women; median age = 44 years [range: 23-68 years]). Eight of 14 (57.1%) patients had primary and 6/14 (42.9%) recurrent MPNSTs. A total of 12/14 (85.7%) patients underwent total tumour resection, whereas 2/14 (14.3%) patients underwent subtotal tumour resection. Malignancies were graded low in 4 (28.6%) and high in 10 (71.1%) cases. A total of 12/14 (85.7%) patients experienced tumour recurrence and 10/14 (71.4%) patients died during the course of follow-up. The 0.5- 1-, 3-, and 5-year survival rates were 64.3, 48.2, 32.1, and 21.4%, respectively. Overall survival was significantly associated with tumour malignant degree (P = 0.012).

Conclusion: Diagnosis of spinal MPNSTs should be made with reference to clinical, radiological, and pathological findings. Surgical resection is the best available option for treating spinal MPNST; however, postoperative prognosis is poor.

Fig. 1

Computed tomographic and magnetic resonance images of spinal malignant peripheral nerve sheath tumours (MPNSTs). a Recurrent spinal MPNST. There was no clear border between the tumour and the surrounding soft tissues. The anatomic structure was difficult to identify. b, c Type IA “dumbbell type” tumour. The tumour was located inside and outside the sacral canal (S1-2) and had an unclear border. Bone erosion of sacrum was evident. d, e Type IA tumour. The tumour was located in the C1-2 intervertebral foramen and was derived from the C2 nerve root. The bone was intact without obvious destruction, but was mildly depressed. The tumour was initially suspected to be a benign schwannoma; however, postoperative pathological examination confirmed the diagnosis of MPNST. f, g Type IB paravertebral tumour. The tumour was located on the left side of the L5 vertebral body and posterior bony elements. The sacroiliac joint was involved with an unclear border. h, i Type II “intraosseous type” tumour. The tumour was located in the L3 vertebral body, which was extensively eroded. The bone cortex was destroyed and the paravertebral soft tissues and spinal canal were involved

Fig. 2

Representative hematoxylin and eosin stained spinal malignant peripheral nerve sheath tumour samples (magnification = ×20). a Tumour cells were spindle shaped with irregular buckled nuclei, marked nuclear atypia, increased cellularity with nuclear enlargement, and hyperchromasia. b A total of 12/16 samples were positive for S-100

Fig. 3

Preoperative and postoperative radiographs of a patient (case 5) with a Type II intraosseous tumour. a The left preoperative cross-sectional computed tomographic (CT) image of the T11 segment shows that the right half of the T11 vertebral body and the right pedicle of the vertebral arch (and accessories) were completely destroyed by the tumour; however, the boundary between the tumour and the paravertebral soft tissue remained clear. The right cross-sectional magnetic resonance image at the same level shows a clear boundary between the tumour and the spinal cord. b The patient underwent en bloc resection involving T11-12 vertebral body partition and resection, artificial vertebral body implantation between T10 and L1, and internal fixation. Follow-up revealed tumour recurrence 30 months surgery. The tumour affected the L1 vertebral body and right accessory. Internal fixation at the posterior site was ruptured. CT-guided biopsy suggested a malignant peripheral nerve sheath tumour of the L1 lamina vertebra. The X-ray images show L1 vertebral body collapse, artificial vertebral body displacement, and rupture of the original pedicle screw at L1. c Combined anterior-posterior en bloc resection of the L1 vertebra was performed via the previous surgical incision (partition and resection). A tibial allograft was implanted between T10 and L2 via the anterior approach, and pedicle screw internal fixation of T9-L3 was performed via the posterior approach. Postoperative X-ray images are shown. d A second recurrence was detected 80 months after the initial surgery; the implanted artificial tibial allograft was invaded. Posterior palliative curettage of the tumour was performed. Bone cement and a titanium rod were inserted at the artificial tibial defect to provide anterior support after curettage. A postoperative X-ray image is shown. At most recent follow-up (after a total of 5 surgical procedures), the patient was alive (with tumour) with Frankel Grade E nerve function