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|LETTER TO EDITOR
|Year : 2021 | Volume
| Issue : 5 | Page : 1471-1472
A Rare Cause of Extraspinal Sciatica: Malignant Peripheral Nerve Sheath Tumor at the Sciatic Notch
Hadhri Khaled, Ben Salah Mohamed, Bellil Mehdi
Spine Unit (UCV), Department of Orthopaedics and Traumatology, Charles Nicolle's Hospital, Boulevard 9 Avril, 1006, Tunis, Tunisia
|Date of Submission||03-Jun-2020|
|Date of Decision||16-Jun-2020|
|Date of Acceptance||10-Jul-2020|
|Date of Web Publication||30-Oct-2021|
Spine Unit (UCV), Department of Orthopedics and Traumatology, Charles Nicolle's Hospital, Boulevard 9 Avril, 1006, Tunis
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Khaled H, Mohamed BS, Mehdi B. A Rare Cause of Extraspinal Sciatica: Malignant Peripheral Nerve Sheath Tumor at the Sciatic Notch. Neurol India 2021;69:1471-2
A 54-year-old female with no pathological history presented with a 1-year right buttock pain irradiating to the homolateral lower limb. It was permanent neuropathic pain not responding to rest and anti-inflammatory drugs, exacerbated when sitting and walking for a long time with no associated low back pain. Physical examination revealed the right sciatica without motor or sensory deficit. The pain does not exacerbate with lumbar spine flexion or coughing. The visual analog scale (VAS) pain score was 8/10; Lasègue's test was negative; the range of motion of the lumbar spine was subnormal. Magnetic resonance imaging (MRI) of the lumbar spine did not show any discovertebral abnormalities or radicular compression at all levels [Figure 1]. Concomitant pelvic MRI exploration revealed an oblong tissular mass at the right sciatic notch measuring 43 × 49 mm with no muscle or rectal involvement but exerting mass effect on initial branches of the right internal iliac artery [Figure 2]. The mass was widely hyperintense at Gadolinium-enhanced fat-saturated T2-weighted sequences with some central millimetric necrotic areas [Figure 3]. Computed tomography-guided needle biopsy evoked the diagnosis of malignant peripheral nerve sheath tumor (MPNST). Surgical treatment was discussed with the patient with special emphasis on neurologic and vascular complications as well as adjuvant therapy and global prognosis. Surgery was declined by the patient. MPNSTs are a rare variety of soft tissue sarcoma of ectomesenchymal origin arising from a peripheral nerve or its sheath. The tumor is most likely to appear in patients with type-1 neurofibromatosis or prior radiation exposure., MPNST arising from the sciatic nerve is very rare, their symptomatology mimics sciatic pain due to herniated disc. Spinal MRI exploration should include at least sacroiliac joints and sciatic notch to avoid missing extraspinal causes of sciatica when clinical features are equivocal. Routine coronal short tau inversion recovery (STIR) imaging of the sacrum improves the assessment of patients presenting with low back pain or sciatica and detects extraspinal causes in up to 2,7% of symptomatic cases. Surgical treatment is the gold standard. Complete resectability depends on location and ranges from 20% in paraspinal MPNSTs to 95% in peripheral locations. According to Wong et al. MPNST has a poor prognosis with reported 5-year survival ranging from 16 to 54%.
|Figure 1: (a) T2-weighted sagittal reconstruction MRI showing no signs of disc herniation or central compression (b) No foraminal compression at right paramedian sagittal reconstruction|
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|Figure 2: Axial T2-weighted pelvic MRI showing tissular mass at the right sciatic notch measuring 43 × 49 mm with no muscle or rectal involvement|
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|Figure 3: (a) Axial Gadolinium-enhanced fat-saturated T2-weighted pelvic MRI showing hyperintense mass at the right sciatic notch with central necrotic areas (b) Coronal view showing the mass effect on the right iliac artery|
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Although rare, MPNST as well as benign forms like schwannoma and neurofibroma of the sciatic nerve should be suspected if the sciatic pain is reported with no correlation with spinal imaging findings.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| » References|| |
Gupta G, Mammis A, Maniker A. Malignant peripheral nerve sheath tumors. Neurosurg Clin N Am 2008;19:533-43.
Suratwala SJ, Kondra K, Cronin M, Leone V. Malignant peripheral nerve sheath tumor of the sciatic nerve presenting with leg pain in the setting of lumbar scoliosis and spinal stenosis. Spine Deform 2020;8:333-8.
Gleeson TG, O'Connell MJ, Duke D, Ryan M, Ennis R, Eustace SJ. Coronal oblique turbo STIR imaging of the sacrum and sacroiliac joints at routine MR imaging of the lumbar spine. Emerg Radiol 2005;12:38-43.
Wong WW, Hirose T, Scheithauer BW, Schild SE, Gunderson LL. Malignant peripheral nerve sheath tumor: Analysis of treatment outcome. Int J Radiat Oncol Biol Phys 1998;42:351-60.
[Figure 1], [Figure 2], [Figure 3]