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NEURORADIOLOGY Table of Contents   
Year : 2004  |  Volume : 14  |  Issue : 2  |  Page : 143-145
Subfrontal cystic Schwannoma : A case report


Department of Radio Diagnosis, and Imaging, Kasturba Medical College and Hospital Manipal-576119, India

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Keywords: Cystic schwannoma, subfrontal schwannoma, neurilemmoma

How to cite this article:
Lakhkar B N, Raphael R. Subfrontal cystic Schwannoma : A case report. Indian J Radiol Imaging 2004;14:143-5

How to cite this URL:
Lakhkar B N, Raphael R. Subfrontal cystic Schwannoma : A case report. Indian J Radiol Imaging [serial online] 2004 [cited 2019 Jul 22];14:143-5. Available from: http://www.ijri.org/text.asp?2004/14/2/143/28570

   Introduction Top


Intracranial schwannomas represent 8% of all intracranial primary tumours, mostly arising from the eighth cranial nerve. Intracranial schwannomas not associated with major cranial nerves account for less than 1% of surgically treated cases of central and peripheral nervous system[1],[2]. In recent reviews of literature, 59 cases of intracranial schwannomas not arising from the cranial nerves were found, of which only 17 cases were found in the subfrontal region[2],[3]. We report a further case of cystic schwannoma in the subfrontal region in a fifty year old man who presented with seizures. Preoperative diagnosis based on MRI findings was cystic meningioma.


   Case report Top


Fifty year old man presented in the emergency department with history of seizures. At admission the patient was unconscious and recovered with in few hours. On neurological examination there were no motor deficits or cranial nerve abnormalities. All metabolic parameters were normal.

Gadolinium enhanced Magnetic Resonance Imaging showed a subfrontal tumour which was predominantly cystic in nature. The lesion was hypointense on T1-weighted images, hyperintense on T2W images and hyperintense to CSF on FLAIR sequences [Figure - 1] & [Figure - 2]. The lesion was showing features suggestive of extra-axial location. Corpus callosum was pushed posteriorly by the lesion. Minimal perilesional edema was noted in the frontal lobes. On contrast the lesion was showing irregular enhancing internal septations [Figure - 3] & [Figure - 4]. Radiological features resembled a cystic olfactory groove meningioma.

Patient underwent craniotomy for resection of the tumour. Intraoperatively, an extraaxial tumour arising from the floor of the frontal fossa was encountered. The tumour was cystic in nature, adherant to the falx and was showing only mild vascularity. Olfactory bulb was seen separately from the tumour. Gross tumour excision was done. Postoperative course was uneventful.

Histopathological diagnosis of schwannoma was confirmed by light microscopy. Microscopy showed a cystic tumor composed of spindle cells arranged in compact, intersecting fascicles. Cells had ovoid or elongated nuclei with fine chromatin, moderate amount of cytoplasm and indistinct cytoplasmic borders. Occasional verocay bodies were seen.[Figure - 5]a & b


   Discussion Top


Schwannomas are tumours arising from the nerve sheaths of peripheral and cranial nerves. Intracranial schwannomas are seen commonly arising from the vestibular portion of eighth cranial nerve and less commonly from the fifth, ninth and tenth cranial nerves

The common presentations of subfrontal schwannomas are headache, seizures, visual disturbances, nasal stuffiness and epistaxis. These tumours grow to a considerable size before clinical diagnosis.

Schwannomas not arising from the major cranial nerves are rare. Because the central nervous system is generally devoid of Schwann cells, the pathogenesis of these tumours are confusing. The theories proposed concerning the origin of these tumours include developmental and non developmental origin. According to non developmental theory the schwannomas not associated with major cranial nerves are usually extraaxial in location. These tumours are thought to be arising from the Schwann cells present on adjacent structures such as perivascular nerve plexus and adrenergic nerve fibers innervating cerebral arterioles. Additionally Schwann cells are also associated with meningeal branches of trigeminal and anterior ethmoidal nerves innervating the anterior cranial fossa and olfactory groove[2]. This theory supports the relatively older age of patients with subfrontal extraaxial schwannomas. The intra-axial schwannomas are more common in younger age group and are supposed to be developmental in nature[2],[4]

Subfrontal schwannomas can have similar radiological features as meningiomas such as extraaxial location, calcification, contrast enhancement and perifocal edema. The presence of cystic component is more suggestive of schwannomas rather than meningiomas[3],[5]. Cystic lesions are found in only 2-4% of meningiomas[6].

In summary, intracranial schwannomas should be considered in the differential diagnosis even though they are not in the close proximity of the major cranial nerves. The extra-axial location of this tumour is consistent with the non developmental origin of tumours. The likely origin of this tumour is from meningeal branches or anterior ethmoidal nerve. The rarity of this tumours and its clinical, radiological and pathological aspects justifies its reporting.

 
   References Top

1.Russel DS, Rubinstein LJ: Pathology of tumours of nervous system, fifth edition, 1989:537-560   Back to cited text no. 1    
2.Paul P Huang, David zagzag, Vallo Benjamin. Intracranial schwannoma presenting as subfrontal tumour: Case report. Neurosurgery 1997;40:194-197.  Back to cited text no. 2    
3.T C Tan, LC HO, HM Chiu, SC L Leung: Subfrontal schwannoma Masquerading as meningioma. Singapore Med journal 2001:42(6):275-277.  Back to cited text no. 3    
4.Casadei GP, Komori T, Scheithaur BW, Miller GM, Parisi JE, Kelly PJ: Intracranial schwannoma. Journal of neurosurgery 1993;79:217-222  Back to cited text no. 4    
5.Ezura M, Ikeda H, Ogawa A, Yoshimoto T. Intracerebral schwannoma: case report. Neurosurgery 1992;30:97-100  Back to cited text no. 5  [PUBMED]  
6.Kulah A, Ilcayto R, Fiskeci C: Cystic meningiomas: Acta neurochir(wien) 1991; 111:108-113.  Back to cited text no. 6    

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Correspondence Address:
B N Lakhkar
Department of Radio Diagnosis, and Imaging, Kasturba Medical College and Hospital Manipal-576 104
India
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Source of Support: None, Conflict of Interest: None


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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]



 

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    Introduction
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    References
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