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| LETTER TO EDITOR |
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| Year : 2013 | Volume
: 61
| Issue : 6 | Page : 675-677 |
Subependymoma causing conus-cauda syndrome: Cured by total excision
Sivashanmugam Dhandapani1, Srinivasan Anirudh1, Ravi Garg1, Rakesh K Vasishta2, Sameer Vyas3
1 Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
3 Department of Radiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| Date of Submission | 13-Jun-2013 |
| Date of Decision | 18-Jul-2013 |
| Date of Acceptance | 21-Dec-2013 |
| Date of Web Publication | 20-Jan-2014 |
Correspondence Address:
Sivashanmugam Dhandapani
Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Chandigarh
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.125375
How to cite this article:
Dhandapani S, Anirudh S, Garg R, Vasishta RK, Vyas S. Subependymoma causing conus-cauda syndrome: Cured by total excision. Neurol India 2013;61:675-7 |
Sir,
Spinal subependymomas are very rare and account for only 2% of all spinal cord tumors, [1] until date 50 cases have been reported. They are predominantly cervical or cervico-thoracic in location, [1] thoracolumbar location is rare and only seven cases have been reported. This is probably the first case of conus-cauda location cured after total excision of the tumor. [1]
A 28-year-old female patient presented with 9 months history of paresthesia in perianal region and both feet with weakness of left foot and straining during micturition. There was mild weakness in S1 root (L >R) with 40-60% sensory loss in S1-S3 dermatomes. Magnetic resonance imaging (MRI) demonstrated fusiform dilation of conus with mass at T11-T12 level which was isointense on T1 and hypointense on T2, enhancing with contrast and with syrinx at lower end [Figure 1]. She underwent T11-L1 laminectomy and on opening dura, tumor was found to be on the surface of conus. It was greyish, firm with well-defined plane of cleavage. There was syrinx at the lower end. Gross total excision was done. Histopathology was characterized by sparsely cellular tumor with cells arranged in loose nodular clusters separated by abundant, dense, fibrillary stroma composed of glial cell processes [Figure 2]a. The tumor cells were monomorphic, with clumped nuclear chromatin and moderate amount of cytoplasm [Figure 2]b. There was no typical perivascular pseudorosette or ependymal tubule. Mitosis was rare to absent. Glial fibrillary acidic protein (GFAP) staining showed diffuse positivity of gliofibrillary background with no particular peri-vascular arrangement [Figure 3]a. S-100 immuno-staining showed no staining of cells [Figure 3]b. Post-operatively patient had transient paresis of left foot which improved subsequently. At 13 months patient is asymptomatic with no residual/recurrent lesion on MRI [Figure 4]. | Figure 1: Pre - operative coronal plain T1 (a), coronal contrast T1 (b), sagittal contrast T1 (c) and sagittal T2 (d) weighted images showing T1 isointense, T2 hypointense mass lesion enhancing with contrast and with cystic changes at lower end
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 | Figure 2: Low power showing fibrillary background with scattered nuclei and occasional perivascular rosettes (b) High power showing fine stippled chromatin against fibrillary background
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 | Figure 3: GFAP staining showing diffuse positivity of the gliofibrillary background. There is no particular peri - vascular arrangement of positive fibers (b) S-100 immunostaining showing no staining of cells
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 | Figure 4: Post - operative coronal contrast T1 (a), sagittal contrast T1 (b) and sagittal T2 (c) weighted images showing no residual/recurrence
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It may be difficult to distinguish subependymoma from other spinal tumors based on the radiological findings alone. Ependymoma (World Health Organization [WHO] II) is seen in cervico-thoracic area, centrally located with surrounding edema. Myxopapillary ependymoma (WHO I) occurs in cauda-equina region, very vascular with dense contrast enhancement. Spinal subependymoma (WHO I) is rare, very well-defined, eccentrically placed, with no surrounding edema and may be hypointense in T2 images. [2] Spinal subependymoma is intramedullary firm, nodular, well-defined, in contrast to the extramedullary, lobulated, vascular and soft consistency of myxopapillary ependymoma. Subependymoma is considered to arise from subependymal glial precursor cells, whereas myxopapillary ependymoma arise from ependymal glia of filum terminale. [3] The main characteristics that distinguish subependymoma from astrocytoma and ependymoma are the variable proportions between ependymal cells, astrocytes and transitional cells. The tumor tends to be well demarcated from surrounding tissue and has an expansive rather than an infiltrative growth nature. The immune-histological phenotypes are different from ependymomas by the modest expression of epithelial membrane antigen probably because there are few ependymal rosettes and by the expression of GFAP and sometimes S-100. [4]
The treatment of choice is surgical resection. As these tumors are non-vascular eccentric located and sharply demarcated at surgery, total resection is usually possible. However in one quarter of cases there may be no demarcation of tumor, with infiltration of the spinal cord permitting only partial excision. As these tumors grow slowly, subtotal excision may be sufficient for long term progression free survival. At present radiotherapy performed in patients with partial removal of the tumor has not been shown to be effective. [5]
In conclusion, conus subependymomas are rare tumors with relatively early presentation due to conus-cauda syndrome, are well-defined, firm, nodular, which may have hypointense T2 signal, having excellent prognosis with curative total excision.
| » References | |  |
| 1. | Iwasaki M, Hida K, Aoyama T, Houkin K. Thoracolumbar intramedullary subependymoma with multiple cystic formation: A case report and review. Eur Spine J 2013;22 Suppl 3:S317-20. 
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| 2. | Hoeffel C, Boukobza M, Polivka M, Lot G, Guichard JP, Lafitte F, et al. MR manifestations of subependymomas. AJNR Am J Neuroradiol 1995;16:2121-9.
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| 3. | Wiestler OD, Schiffer D. Subependymoma. In: Kleihues P, Cavenee WK, editors. Pathology and Genetics: Tumours of the Nervous System. Lyon: IARC Press; 2000. p. 80-1.
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| 4. | Lach B, Russell N, Benoit B. Atypical subependymoma of the spinal cord: Ultrastructural and immunohistochemical studies. Neurosurgery 1990;27:319-25.
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| 5. | Tacconi L, Johnston FG, Thomas DG. Subependymoma of the cervical cord. Clin Neurol Neurosurg 1996;98:24-6.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
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