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|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 6 | Page : 1340-1341
Intradural benign epithelioid schwannoma of the lumbar spine
Joshua T Wewel1, Erwin Z Mangubat1, Jyothi Patil2, Kurian P Abraham2, Sepehr Sani1
1 Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA
2 Department of Pathology, Rush-Copley Medical Center, Aurora, Illinois, USA
|Date of Web Publication||11-Nov-2016|
Joshua T Wewel
Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Wewel JT, Mangubat EZ, Patil J, Abraham KP, Sani S. Intradural benign epithelioid schwannoma of the lumbar spine. Neurol India 2016;64:1340-1
Benign peripheral nerve sheath tumors are relatively common; however, the benign epithelioid schwannoma (BES) variant is exceedingly rare, mainly affects peripheral nerves, and is frequently malignant., Rare central nervous system occurrences of BES have been reported involving the cranial nerves [Table 1].
|Table 1: Benign epithelioid schwannoma reported involving cranial nerves and spinal cord nerve roots|
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The patient was a 55-year-old female with a 1-year history of low back pain radiating down the back of her legs in a radicular fashion. Motor and sensory evaluation revealed fully preserved function with normal reflexes. The stigmata of neurofibromatosis were absent. Magnetic resonance imaging (MRI) with and without contrast demonstrated an enhancing, well-circumscribed, 11 × 14 mm intradural mass at the second lumbar level [Figure 1]a and [Figure 1]b. After an L2 laminotomy, the dura was opened, revealing the well-encapsulated fusiform mass. Circumferential dissection was feasible and a gross total resection was performed.
|Figure 1: Pre-operative T1-weighted postcontrast sagittal (a) and T1-weighted postcontrast axial (b) magnetic resonance imaging (MRI) sequences illustrating an intradural enhancing mass at L2, displacing the nerve roots of the cauda equina posteriorly. The three-month postoperative T1-weighted postcontrast sagittal (c) and T1-weighted postcontrast axial (d) MRI sequences illustrating a gross-total resection. Two year postoperative T1-weighted postcontrast sagittal MRI (e) illustrating no recurrence|
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Histological sections demonstrated a nodular proliferation of spindle to epithelioid cells with bland nuclei in a myxoid background [Figure 2]a. Mitotic figures were rare (less than 1 per 10 high power fields). S-100 and vimentin immunostains were uniformly immunopositive [Figure 2]b. CD56 staining demonstrated diffuse moderate immunoreactivity. Epithelial membrane antigen was focally immunopositive in the perineural cells of the capsule. There was no immunoreactivity for glial fibrillary acidic protein, cytokeratin AE1/AE3, cytokeratin 8/18, or progesterone receptors.
|Figure 2: Histopathologic photomicrographs of an hematoxylin and eosin stained section (a) revealing nodular proliferation of spindle to epithelioid cells with bland nuclei in a myxoid background, with normal peripheral nerve structure noted focally at the edges of the lesion, and an immunoperoxidase stained section (b) illustrating uniform S-100 immunopositivity|
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The postoperative course was uncomplicated with resolution of radicular symptoms. A postoperative MRI at 3-month follow-up was consistent with gross-total resection and resolution of mass effect [Figure 1]c and [Figure 1]d. No recurrence was seen at 2 years [Figure 1]e.
The World Health Organization classifies epithelioid schwannomas as low-grade malignant peripheral nerve sheath tumors with a predominance of epithelioid cells, histologically resembling a carcinoma, or an amelanotic melanoma.,,, The dermatological variant is commonly found in subcutaneous tissues and cumulative data from other reported cases indicate that small tumor size (<3 cm), good circumscription, and superficial location are pathologic features that favor a benign clinical course after conservative excision.,
Epithelioid schwannomas present as slow growing masses that produce abrupt neurological symptoms due to rapid enlargement, causing a fusiform expansion of the involved nerves. Clinical presentation is similar to that of a schwannoma or a meningioma affecting a focal nerve root, and radiographically, they may remain indistinguishable. Therefore, reliance is placed purely on histological and immunohistochemical grounds for establishing an unequivocal diagnosis. It was previously considered that BES have an aggressive course with local infiltration and metastasis. Surgical excision remains the mainstay of treatment of BES, whereas malignant variants may require more radical surgery, supplemented by adjuvant chemotherapy and radiation for subtotal resection, metastasis, or recurrence., Long-term radiographic follow-up is strongly recommended.
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[Figure 1], [Figure 2]