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Table of Contents    
LETTER TO EDITOR
Year : 2012  |  Volume : 60  |  Issue : 3  |  Page : 335-337

Supratentorial intraparenchymal schwannoma mimicking a glial tumor


1 Department of Radiotherapy, Tata Memorial Hospital, Mumbai, India
2 Department of Neurosurgery, King Edward Memorial Hospital, Mumbai, India
3 Department of Neuropathology, Tata Memorial Hospital, Mumbai, India
4 Department of Neuropathology, King Edward Memorial Hospital, Mumbai, India

Date of Submission24-Jan-2012
Date of Decision26-Jan-2012
Date of Acceptance13-May-2012
Date of Web Publication14-Jul-2012

Correspondence Address:
Amit Mahore
Department of Neurosurgery, King Edward Memorial Hospital, Mumbai
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.98531

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How to cite this article:
Sharma P, Mahore A, Kansal R, Epari S, Kataria NG. Supratentorial intraparenchymal schwannoma mimicking a glial tumor. Neurol India 2012;60:335-7

How to cite this URL:
Sharma P, Mahore A, Kansal R, Epari S, Kataria NG. Supratentorial intraparenchymal schwannoma mimicking a glial tumor. Neurol India [serial online] 2012 [cited 2019 Aug 23];60:335-7. Available from: http://www.neurologyindia.com/text.asp?2012/60/3/335/98531


Sir,

A 25-year-old man presented with a history of occipital headache of 6 weeks duration and a single seizure 4 weeks before admission. He had no neurologic deficit or neurocutaneous markers. Computed tomography (CT) of brain revealed a cystic lesion with a mural nodule in the right parieto-occipital lobe [Figure 1]a and b. Magnetic resonance imaging (MRI) showed a well-defined cystic lesion (5.7 s 3.4 cm) with a solid mural nodule lateral to the occipital horn of right lateral ventricle. [Figure 1]c and d. The provisional diagnosis was pilocytic astrocytoma or pleomorphic xanthoastrocytoma. He underwent right parieto-occipital craniotomy and excision of the tumor through transcortical trans-sulcal approach. The cyst contained xanthochromic fluid and the mural nodule was firm, gray, and vascular, which was totally excised. Histology, the tumor was composed of compact fascicles of elongated spindle cells with focal areas of loose stroma [Figure 2]a-c. No Rosenthal fibers or eosinophilic granular bodies were identified. Differentials of pilocytic astrocytoma and schwannoma were considered at this stage. Subsequent ancillary methods showed a rich intratumoral pericellular network of reticulin [Figure 2]d, immune-reactivity for S-100 protein [Figure 2]e, glial fibrillary acidic protein [Figure 2]f, CD 56 (N-CAM), whereas it was immunonegative for p53 protein. Finally, in view of the absence of Rosenthal fibers and diffuse, rich intratumoral pericellular reticulin network, the diagnosis of schwannoma was favored. Brain MRI done at followup showed complete excision of tumor with gliosis at the site of surgery [Figure 1]e. The patient had no added neurologic deficit after 18 months of surgery.
Figure 1: Precontrast (a) and postcontrast (b) axial images of computed tomography scan of brain showing predominantly cystic tumor adjacent to the right occipital horn of lateral ventricle with solid nodule, which shows strong contrast enhancement. Axial (c) and sagittal (d) image of magnetic resonance imaging (MRI) of brain showing cystic tumor with solid nodule lateral to the right occipital horn of lateral ventricle. Axial image (e) of MRI scan of brain showing complete excision of lesion with gliotic scar at the site of tumor

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Figure 2: Photomicrographs showing tumor with loose stroma areas (a and b: H and E, ×50) alternating with cellular spindle cell areas and interspersed hyalinized blood vessels (c: H and E, ×200). The tumor shows rich intratumoral reticulin (d: reticulin stain, ×200), immunopositivity for S-100 protein [e: immunohistochemistry (IHC, ×200) and glial fibrillary acidic protein (f: IHC, ×200)

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Schwannomas are benign tumors arising from the Schwann cells, which produce the myelin sheath around the peripheral nerves, therefore schwannomas are most commonly seen in the peripheral nervous system. [1],[2],[3] Intra-axial ectopic schwannomas unrelated to cranial nerves are extremely rare. [3],[4],[5],[6] The occurrence of these tumors in the intraparenchymal location is a curious entity as the Schwann cells are not native to the central nervous system. [1],[2],[3] Many hypotheses suggesting its developmental origin and otherwise have been suggested. [2],[3] Disordered embryogenesis, failed migration of the neural crest cells, ectopic Schwann cell rests, and derivation from differentiation of multipotent mesenchymal neural crest cells or schwannosis (a term coined by Russell and Rubinstein for hamartomatous lesions consisting of Schwann cells) are some thoughts; however, the facts still remain unclear. [1],[2],[3] There are no pathognomic radiologic features described; however, the reported features include calcification, cyst formation, gliosis, and superficial or periventricular location. [7],[8]

Microscopically these tumors are characterized by 2 tissue types. [2],[7] Antoni type A tissue shows fascicles of spindle-shaped Schwann cells streaming around numerous acellular, eosinophilic areas surrounded by paralleled or palisaded spindled cells with blunt, elongated nuclei occasionally forming Verocay bodies. The second tissue type, Antoni type B, lacks the Verocay bodies and consists entirely of less cellular and more randomly arranged spindle cells in a loose, myxomatous stroma. S100 protein is a diagnostic histochemical marker for schwannoma, however, is not exclusive. [1],[2],[7] Differentiating schwannoma from other tumors is a difficult challenge because of its uncharacteristic clinical presentation, and radiologic and routine light microscopy appearances. [2],[5],[6],[7],[8] Wherever resources permit, immunohistochemistry and ultrastructural features (electron microscopy) of typical interdigitating cytoplasmic processes covered by a basement membrane and special stains, such as Leu 7 and calretinin, may help in providing the diagnosis. [2],[3],[7]

Intra-axial schwannomas may rarely present as cystic lesions with mural nodules and can be easily mistaken for other low-grade tumors, such as pilocytic astrocytomas or pleomorphic xanthoastrocytoma. It is important to recognize this tumor due to its benign nature, resemblance to glial tumors, and an excellent response to resection alone.

 
  References Top

1.Feigin I, Ogata J. Schwann cells and peripheral myelin within human central nervous tissues: The mesenchymal character of Schwann cells. J Neuropathol Exp Neurol 1971;30:603-12.  Back to cited text no. 1
[PUBMED]    
2.Russell DS, Rubinstein LJ. Pathology of tumours of nervous system. 5 th ed. London: Edward Arnold; 1989. p. 535-60.  Back to cited text no. 2
    
3.Frim DM, Ogilvy CS, Vonsattal JP, Chapman PH. Is intracerebral schwannoma a developmental tumor of children and young adults? Case report and review. Pediatr Neurosurg 1992;18:190-4.  Back to cited text no. 3
[PUBMED]    
4.Bhatoe HS, Srinivasan K, Dubey AK. Intracerebral schwannoma. Neurol India 2003;51:125-7.  Back to cited text no. 4
[PUBMED]  Medknow Journal  
5.Takei H, Schmiege L, Buckleair L, Goodman JC, Powell SZ. Intracerebral schwannoma clinically and radiologically mimicking meningioma. Pathol Int 2005;55:514-9.  Back to cited text no. 5
[PUBMED]  [FULLTEXT]  
6.Menkü A, Oktem IS, Kontaº O, Akdemir H. Atypical intracerebral schwannoma mimicking glial tumor: Case report. Turk Neurosurg 2009;19:82-5.  Back to cited text no. 6
    
7.Zagardo MT, Castellani RJ, Rees JH, Rothman MI, Zoarski GH. Radiologic and pathologic findings of intracerebral schwannoma. AJNR Am J Neuroradiol 1998;19:1290-3.  Back to cited text no. 7
    
8.Di Biasi C, Trasimeni G, Iannilli M, Polettini E, Gualdi GF. Intracerebral schwannoma: CT and MR findings. AJNR Am J Neuroradiol 1994;15:1956-8.  Back to cited text no. 8
    


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