Intracranial schwannomas of the brain are rare andaccount for account for 8% of all primary brain tumoursin adults, with most cases being acoustic neuromas, in-traparenchymal schwannomas of the brain are rare.Gibson et al. (1) reported the first English-language ac-count of an intraparenchymal intracerebral schwanno-ma in 1966. Since then, several other cases of this neo-plasm have been reported (2, 3). We present a case of anunusual intracranial intraparenchymal schwannomaand discuss the clinical and neuroradiological aspects ofthis tumor.

Case Report

A 51-year-old woman was admitted to our hospitalwith complaints of intermittent headaches on June 27,2007. Upon admission, the neurological examinationwas normal with no specific signs or specific familialhistory. The patient’s skull X-ray was normal; however,

a contrast enhanced axial CT scan revealed a 1.3 cmsized homogeneous enhancing mass in the left parietallobe, without a cystic component (Fig. 1). A pre-en-hanced CT scan showed no internal calcification. AnMRI (Fig. 2) revealed that the mass exhibited slight hypointensity on the T1-weighted image and hyper intensityon the T2-weighted image with minimal perilesionaledema. The Gd-enhanced T1-weighted image showedhomogeneous enhancement with no calcification or cys-tic component. The patient underwent a complete tu-mor removal on June 28. The tumor was pathologicallyconfirmed to be a schwannoma.

Discussion

Intraparenchymal schwannomas of the brain are raretumours, but have several characteristic features whichserve to classify them as a separate entity from their farmore common vestibular counterparts. Intraparenchy-mal schwannomas show no female predominance, un-like vestibular schwannomas, with the majority of casesoccurring in children and young adults. In contrast,vestibular schwannomas rarely occur in children unlessthey are associated with neurofibromatosis of type 2.The most common signs and symptoms include

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Parietal Intraparenchymal Schwannoma: Case Report1

Seong Hwan Kim, M.D., Tae Woong Chung, M.D., Woong Yoon, M.D., Gwang Woo Jeong, M.D., Heoung Keun Kang, M.D.

1Department of Diagnostic Radiology, Chonnam National UniversityHospitalReceived May 26, 2008 ; Accepted August 21, 2008Address reprint requests to : Tae Woong Chung, M.D., Department ofDiagnostic Radiology, Chonnam National University Hospital, 8 Hak-dong, Dong-gu, Gwang-Ju 501-191, Korea. Tel. 82-62-220-5746 Fax. 82-62-226-4380 E-mail: twchung@jnu.ac.kr

We report a case of an intraparenchymal schwannoma of the left parietal lobe. A 51-year-old woman was admitted to our hospital with complaints of intermittentheadaches. Computed tomography and magnetic resonance images revealed a 1.3 cmsized intra-axial homogeneous enhancing mass in the left parietal lobe. The lesion waspathologically confirmed to be a schwannoma.

Index words : NeurilemmomaParietal lobeBrain neoplasms

headache, seizures and focal neurologic deficits.Radiologically, peritumoral edema with or without

gliosis, in either a superficial or deep periventricular lo-cation, is believed to be characteristic of intraparenchy-mal schwannomas, as reported in previous case studies(3). However, perilesional edema has only been shownin supratentorial intracerebral schwannomas and not in-fratentorial schwannomas (2). Although cyst formationand calcification are also believed to be characteristic ofintraparenchymal schwannomas (3), the lesion in thisreport did not present either. This patient had minimalperilesional edema. The cause of the perilesional edemais uncertain. Vascular endothelial growth factor (VEGF)messenger RNA expression has been implicated in ede-ma formation around some meningiomas and may be

an important etiologic factor explaining the peritumoraledema in other benign neoplasms (4). However, thepresence of VEGF in intracerebral schwannomas hasnot been confirmed and its role in edema formation re-quires further investigation. Chronic edema can resultin the degeneration of white matter and gliosis, whichmay explain the frequent association of these findings(5).

The characteristic pathologic and imaging features ofintraparenchymal schwannomas include calcification,cyst formation, peritumoral edema and gliosis, as wellas superficial or periventricular location. Calcification,which is believed by some to be a characteristic findingin intracerebral schwannomas (6), was not observed ra-diologically nor confirmed histopathologically in this

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A B

Fig. 1. A pre-enhanced (A) and con-trast enhanced (B) axial CT scan re-veals a 1.3 cm sized intra-axial homo-geneous enhancing mass in left pari-etal lobe without a cystic component.There was no internal calcification.

A B CFig. 2. For the magnetic resonence imaging, the intra-axial mass showed a slight hyposignal intensity on a T1-weighted axial image(A) and hypersignal intensity on a T2-weighted axial image (B) with minimal perilesional edema. A Gd-enhanced T1-weightedcoronal image (C) shows homogeneous enhancement.

case. Calcification has only been documented in 6 casesin a review (3). Cystic formation, which is another char-acteristic feature which has been frequently observed inintracerebral schwannomas, was also not observed inthis case.

The MRI findings of intracerebral schwannomas arevariable. DiBiasi et al. (7) reported a 1.5-cm well- cir-cumscribed mass located within the superficial frontallobe and showing a hypointense T1 signal and a hyper-intense T2 signal that was intensely and homogenouslyenhanced. In addition, a 5-cm cystic frontal lobe masswith a solid, homogeneously enhancing component hasalso been reported (6). The solid portion showed T1 hy-pointensity and mixed T2 hypointensity and hyperin-tensity.

The origin of intracerebral shcwannomas is uncertain;however, a few hypotheses exist. The first hypothesis isthat intracerebral schwannomas arise from the prolifer-ation of schwann cells in the perivascular perineuralnerve plexus (8). Another hypothesis states that intrac-erebral schwannomas arise from ectopic schwann cells,which are derived from the neural crest, or fromschwann cells converted from mesenchymal cellswhich are capable of multipotential differentiation inthe pia matter of the meninges (2). However, the firsthypothesis is more widely accepted and is also the mostsupported theory in spinal intramedullary schwanno-mas.

The differential diagnosis of these lesions includesgangliomas, meningiomas, pilocytic astrocytomas, pleo-morphic xanthoastrocytomas, and tuberculomas.Gangliogliomas are extremely similar in appearance,

but are actually rare neuronal tumors that happen to bemost commonly found within the temporal lobes. Cysts,contrast enhancement, and calcification may also bepresent (9). Meningiomas were also considered in thepossible radiological differential diagnoses. These gener-ally have a well-defined dural attachment, a 50% inci-dence of calcification, and a 12% incidence of cyst for-mation. Pilocytic astrocytomas are the most commonsolid-cystic tumors in the supratentorial compartment inchildren. Unlike intracerebral schwannoma cases, sur-rounding edema is rarely present. Pleomorphic xan-thoastrocytoma is a typically benign, supratentorial as-trocytoma, which occurrs primarily in children andyoung adults at an equal sex ratio. The MR imagingcharacteristics are variable, with both the T1 isointensi-ty and hypointensity and mixed T2 isointensity and hy-perintensity (10). Similar to intracerebral schwannomas,cysts and mild to moderate edema are common. Thisneoplasm is also located superficially and involves thecortex and leptomeninges, which may be firmly at-tached to the dura; however, calcification is rarely seenon CT scans or histopathological assessments, whichmay help differentiate pleomorphic xanthoastrocytomasfrom intracerebral schwannoma. Tuberculomas are pos-sibly the most common lesions in this part of SouthAsia, but those in the supratentorial compartment areoften multiple, located at the grey-white junction andhyperdense on the non-contrast CT scan with ring en-hancement. They uncommonly calcify and in the non-miliary form rarely generate vasogenic edema.

In conclusion, a rare manifestation with a frontal lo-bar, intraparenchymal homogeneous enhancing solidmass, with minimal perilesional edema, without calci-fication or cyst formation has been presented in this re-port. Although usual intracerebral schwannoma is arare, benign neoplasm, which is characterized by cystformation, calcification, as well as perilesional edema orgliosis.

References

1. Gibson AA, Hendrick EB, Conen PE. Case reports. Intracerebralschwannoma: report of a case. J Neurosurg 1966;24:552-557

2. Tsuiki H, Kuratsu J, Ishimaru Y, Nakahara T, Kishida K,Takamura M, et al. Intracranial intraparenchymal schwannoma:report of three cases. Acta Neurochir (Wien) 1997;139:756-760

3. Zagardo MT, Castellani RJ, Rees JH, Rothman MI, Zoarski GH.Radiologic and pathologic findings of intracerebral schwannoma. JNeuroradiol 1998;19:1290-1293

4. Kalkanis SN, Carroll RS, Zhang J, Zamani AA, Black PM.Correlation of vascular endothelial growth factor messenger RNA

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Fig. 3. Histologic findings of the tumor shows compact fasci-cles of spindle cells which are composed of elongated hyper-chromatic palisading nuclei (×100).

expression with peritumoral vasogenic cerebral edema in meni-giomas. J Neurosurg 1996;85:1095-1101

5. Feigin I, Popoff N. Neuropathological changes late in cerebral ede-ma: the relationship to trauma, hypertensive disease andBinswanger’s encephalopathy. J Neuropathol Exp Neurol 1963;22:500-511

6. Ezura M, Ikeda H, Ogawa A, Yoshimoto T. Intracerebral schwan-noma: case report. Neurosurgery 1992;30:97-100

7. DiBiasi C, Trasimeni G, Iannilli M, Polettini E, Gualdi GF.Intracerebral schwannoma: CT and MR findings. AJNR Am JNeuroradiol 1994;15:1956-1958

8. Riggs H, Clary W. A case of intramedullary sheath cell tumor ofthe spinal cord. Consideration of vascular nerves as a source of ori-gin. J Neuropathol Exp Neurol 1957;16:332-336

9. Castillo M, Davis PC, Takei Y, Hoffman JC Jr. Intracranial gangli-oglioma: MR, CT, and clinical findings in 18 patients. AJNR Am JNeuroradiol 1990;11:109-114

10. Lipper MH, Eberhard DA, Phillips CD, Vezina LG, Cail WS.Pleomorphic xanthoastrocytoma, a distinctive astroglial tumor:neuroradiologic and pathologic features. AJNR Am J Neuroradiol1993;14:1397-1404

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대한영상의학회지 2008;59:221-224

두정엽 실질에 발생한 신경집종: 증례 보고1

1전남대학교병원 영상의학과

김성환·정태웅·윤 웅·정광우·강형근

저자는 좌측 두정엽에 발생한 뇌 내 신경집종 한 예를 보고하고자 한다. 51세 여자 환자가 간헐적으로 있는 두

통을 주소로 내원하였다. 컴퓨터단층촬영과 자기공명영상에서 좌측 두정엽에 균질하게 조영증강되는 1.3 cm의 축

내성 종양이 발견되었다. 이 병변은 병리학적으로 신경집종으로 확진되었다.