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|LETTER TO EDITOR
|Year : 2014 | Volume
| Issue : 6 | Page : 675-677
Multi-centric spinal extradural malignant peripheral nerve sheath tumor: A case report
Harsimrat Bir Singh Sodhi1, Ankur Kapoor1, Pravin Salunke1, BD Radotra2
1 Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Histopathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
|Date of Submission||24-Oct-2014|
|Date of Decision||24-Oct-2014|
|Date of Acceptance||24-Oct-2014|
|Date of Web Publication||16-Jan-2015|
Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sodhi HB, Kapoor A, Salunke P, Radotra B D. Multi-centric spinal extradural malignant peripheral nerve sheath tumor: A case report. Neurol India 2014;62:675-7
Malignant peripheral nerve sheath tumors (MPNSTs) are soft tissue sarcomas arising from the coverings of peripheral nerves or from the neural tissue itself.  Gross total surgical resection followed by adjuvant radiotherapy remains the treatment of choice.  Multiple lesions are uncommon without neurofibromatosis-1 (NF-1) and usually involve various organs. Our case was unique in being multicentric, with three noncontiguous spinal extradural lesions without associated NF-1.
A 32-year-old female presented with progressive painless lump over the upper and mid dorsal region, since last 2 months, alongwithheaviness in both lower limbs over the last 15-20 days. Neurological examination was normal except for involvement of posterior column. There were no cutaneous markers of NF or peripheral neurofibromas. Gadolinium-enhanced magnetic resonance imaging (MRI) of whole spine revealed three noncontiguous lesions, one at the level of C2-3, second from T1-2, and third from T3-6. All the lesions were iso- to hypointense on T1-weighted (T1W), hypointense on T2W, with homogenous contrast enhancement. There was thecal sac indentation by the uppermost lesion, while T1-2 lesion was extending laterally, causing neural foraminal compromise [Figure 1]. The lowermost lesion was primarily in the paraspinal muscular plane, extending down to the dural sleeve of exiting nerve root. Screening MRI of the entire craniospinal axis revealed no other lesions. Fine needle aspiration cytology (FNAC) done from the back swelling showed spindle-shaped cells with mild atypia, suggestive of soft tissue sarcoma.
|Figure 1: (a-c) Axial contrast MRI images showing extra-axial contrast enhancing lesion at level of foramen magnum, T1, and T4 with thecal compression. (d-f) Parasagittal and mid-sagittal T2 and contrast MRI showing noncontiguous lesions with thecal compression. MRI = Magnetic resonance imaging|
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The surgical procedure consisted of two separate surgical incisions, one for removal of upper lesion, and the other for the excision of lower two lesions (T1-2 and T3-6). C2 right hemilaminectomy and gross total excision of lesion was done through upper incision. Through the second incision, T1-2 right hemilaminectomy and gross total excision of lesion, including removal of part going into the neural foramina at T1-2 level, was achieved. The lowermost extradural lesion, which was located mainly in the paraspinal location, was also excised through the second incision. This lesion was eroding the lamina and going towards the neural foramina, and near total resection was achieved. The gross appearance of the lesions was grayish, soft, rubbery, and minimally vascular. There was invasion of the bone and muscular planes by the lowermost lesion located at the thoracic level. There was no intradural extension. Histopathological examination revealed MPNST [Figure 2]a. Patient received postoperative radiotherapy, 34Gy over a period of 7 weeks. Patient is doing fine at 8 months postop, with no neurological deficit, and with no residual/recurrent lesion on follow-up MRI [Figure 2]b.
|Figure 2: (a) Spindle cell interlacing fascicles infiltrating the skeletal muscle fibers. The black ink on left upper margin represents the margins (hematoxylin and eosin (H and E), ×10). (b) Postoperative MRI showing gross total excision and no more thecal compression|
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MPNSTs are rare malignant lesions of peripheral nerve sheath origin, with an incidence of approximately 0.001% in general population and 2-5% in patients with NF-1. They may arise denovo, from malignant degeneration of benign schwannomas, or after prior radiotherapy exposure.  Spinal MPNSTs are quite rare, with subcutaneous tissues of trunk and extremities being the most common location.  Most cases of MPNST occur in the age group of 20-50 years, with earlier occurrence in patients with NF-1.  The spinal location of MPNSTs is quite uncommon. There has been a single case report of multifocal MPNST involving the bone and dura at the spinal level.  Multifocal MPNST at different locations (spinal and extraspinal) has also been described.  However, synchronous multicentric spinal extradural MPNST has never been reported.
These tumors usually present with gradually enlarging painless lump, localized mild pain, or sensory or motor symptoms depending upon the location.  Surgical resection, with a negative surgical margin, forms the primary modality of treatment and is associated with best prognosis, although this becomes difficult in spinal location. In our patient, we achieved near total resection of all the three lesions, including removal of foraminal part of T1-2 lesion. Adjuvant treatment consists of radiotherapy, the role of chemotherapy being controversial, as these tumors are considered chemoresistant. 
Multicentricity along the spinal axis can be explained by spread along CSF pathways. However, this theory cannot explain multiple extradural noncontiguous lesions. Blood-borne metastasis in MPNST has been described. However, synchronous metastasis occurring along the dura appears less plausible. It is possible that genetic mutation apart from NF-1 may be responsible for such synchronous non-contiguous multicentric spinal extradural lesions. The rarity of spinal MPNST precludes the establishment of any formidable genetic basis.
The present case highlights the role of whole spine screening in case of suspected spinal MPNST, to rule out any synchronous lesion, even in non-NF-1 patients. The gross total surgical excision with negative surgical margins, portends good prognosis in spinal cases. Adjuvant radiation plays a role where radical resection is not possible due to proximity to neural structures.
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. Diagnosis, treatment and survival of 65 patients with malignant peripheral nerve sheath tumors. Anticancer Res 2014;34:777-83.
Lau D, Moon DH, Park P, Hervey-Jumper S, McKeever PE, Orringer DA. Radiation-induced intradural malignant peripheral nerve sheath tumor of the caudaequina with diffuse leptomeningeal metastasis. J Neurosurg Spine 2014;12:1-8.
Roopesh Kumar VR, Madhugiri VS, Sasidharan GM, Shankar Ganesh CV, Gundamaneni SK. Multifocal spinal malignant peripheral nerve sheath tumor in an immune compromised individual: Case report and review of literature. Eur Spine J 2014;23 Suppl 2:236-41.
Leena JB, Fernandes H, Swethadri GK. Sporadic multifocal malignant peripheral nerve sheath tumor- A rare presentation: Multifocal MPNST. Indian J Surg 2013;75 Suppl 1:25-6.
[Figure 1], [Figure 2]