대 한 방 사 선 의 학 회 지 1992; 28(1) : 51~55 Journa l of Korean Radiological Society. January. 1992

Intracranial Calcified Schwannomas: Report of Two Cases

Jong Deok Kim, M.D. , Duck Hwan Chung, M.D.

Department of Diagnostic Radiology. College of Medicine. Inje University

- Abstract-

Calcification is exceedingly rare in schwannomas . In the literatures. we found only lhree reports of schwannomas

with calcification. We report two cases of intracranial calcified schwannomas. one in lhe anterior cranial fossa and

the other in the middle cranial fossa

Index Words: Anterior cranial fossa. abnormal intracranial caJcification 129.81

Middle cranial fossa. schwannoma 128.3641

INTRODUCTION

Schwannomas(neurilemmomas or neurinomas)

are benign nerve sheath tumors of schwann cell

origin that occur along the course ofthe sensory com­

partment of crnia1. periphera1. and symphathetic

nerves with the exception of the olfactory and optic

nerves. The vestibular part ofthe eighth cranial nerve

is the sites of origin of more than 60% of a1l schwan­

nomas. a1though they may also occur on the fifth

nerve. Regressive change in this tumor such as cystic

degeneration and hemorrhagic necrosis are well

known( 1-2). but the descriptions about caJcification

within schwannomas are very rare(3-7) . We present

two cases of intracranial calcified schwannomas. one

probably arised from the floor of anterior cranial fossa

and the other from trigeminal nerve in the middle

cranial fossa.

CASE REPORTS

a finger-nail sized swe1ling at the right medial can­

thus. A moderate degree ofhyperplasia ofthe left mid-

dle concha was detected by anterior rhinscope

Laboratory findings were normal. Plain films reveal­

ed thin and long. cuπilinear calcifications in the fron­

tal area and bony destruction in the anterior frontal

base including the crista gali and the upper nasal sep­

tum. with loss of the normal contour of the frontal

sinus and haziness in the frontal and the upper

ethmoid sinus region. On CT scan(Fig. la.b.c.d) about

6 x 7 x 8Cm sized. sharply demarcated. lobular . and

expanding mixed density mass was noted. The mass

was composed of we1l-enhancing solid- and non­

enhancing cystic components with a thick calcified

wa1l occupying most of the e thmoid- and entire fon­

tral sinuses. There was extradural intracranial and

extraconal intraorbital extension . and destruction of

the anterior frontal and the ethmoid bones. A bifron­

tal transcoronal craniotomy was performed . At

surgery. a brownish-ye1low mass was present bet­

ween the frontal lobe of the brain and the frontal

sinuses. There was destruction ofthe frontal sinuses

Case 1 and severe a dhesion to the dura . The mass was ex

A 36-year-old woman was admitted to our hospital tended to both ethmoid sinuses. The pathologic ex-

because of protrusion and intermittent diplopia of the am ination (Fig. l e) revealed schwa nnoma of An toni

left eye over the past two months. Physical examina- A pattern which inc1 uded a pallisading appearance

tion revealed slight exophtha lmos of the left eye and of nuc1ei a bout a central mass of cytoplasm(Verocay

이 논문은 1991년 7월 27일 접수하여 1991년 10월 30일에 채택되었음

Received July 27. Accepted October 30. 1991

- Sl -

Journal 01 Korean Radi미 ogical Society 1992 ; 28( 1) : 51 ~55

c d

body) intennixed with a texture of fibers 킹1d cells(An­

toni B). No recurrence was found on follow-up study

for 9 months

Case 2.

Fig. 1. CT of the Case 1 Pre-(a.b) and post-enhanced(c.d) CT scans show about 6 x 7 x8Cm sized. sharply demarcated ‘ lobular. expan­ding. mixed density mass composed of well-enhancing soft tissue- and cystic components with calcifjed wall involving the l100r of anterior cranial fossa. which extends into the frontal and ethmoid sinuses and extraconal intraobital region accompanying with severe destruction of the anterior frontal and ethmoid bones. Patholo­gic examination(Hematoxylin-Eosin; original magnification . x lOO)(e) reveals schwannoma of Antoni A pat­tern including pallisading ap pearance of nuclei about a centra l mass of cytoplasm(Verocay body) in­termixed with texture of fibers and cells(Antoni B)

A 12-year-old boy had suffered from visual distur­

bance with limitation of lateral gaze of the right eye.

and headache and nausea for about one year.

Physical examination revealed mild exophathalmos

and protrusion of the temporal portion of the right­

sided skull. Laboratory findings were unremarkable

Plain skull films revealed increased convolutional

markings ‘ a sharply delineated bone defect in the

medial temporal pyramid. enlargemnt of the superior

orbital fissure ‘ and expansion of the right middle

cranial fossa. On CT scan(Fig. 2a.b) about 8.5 x 6 .5 x

6.5Cm sized. well encapsulated. extraaxial ‘ mixed

density mass. occupying the right middle cranial

fossa was noted . The mass consisted of peripheral.

well-enhancing solid- and central cystic portions with

thick linear. calcified capsule. A bone defect in the

b

c d

Jong Deok Kim , et al : Intracranial Calcified Schwannomas

Fig. 2. CT and MRI of the Case 2 . Pre-(a) and postcontrast(b) axial CT scans reveal about 8.5x6.5x6.5Cm sized , well encapsulated ‘ extraaxia l. mixed density mass of peripheral well-enhancing solid-and central cystic portions with thick linear. calcified wall occpying right middle cranial fossa and bone defect in this expanded rniddle fossa. sharp erosion of the anteromedial pyramid. involve­m ent of the optic canal and adjacent

ï: - ~sphenoid sins wa\l. Right CPA cistern ..，.j톨 and 4th ventricle are compressed and

~displaced. On Coronal MRI. peripheral portion of the tumor is iso­i and S뺀Y low 51 on precontrast

...... TIWl(c) with good enhancement on

.. ' postcontrast T 1 Wl(d) . and central portion is cystic. Cornpressed right cavernous ICA. destruction of the floor of right middle craial fossa and obstructive hydrocephalus are also well visualized .(TR/TE 400115. 0 .5T Toshiba MRT-50A 5uperconducting sytem)

floor of the expanded middle cranial fossa. sharp ero- calcified consistency occupying the entire middle

sion of the anteromedial pyramid. and involvem ent cranial fossa was found and nearly total removal of

of the optic canal and a이acent lateral wall of the the mass was performed. The nerve origin of the

sphenoid s inus were demonstrated . The right CPA tumor could not be found . l'vlicroscopic examination

c istern and 4th ventricle were compressed and confirmed the mass to be a schwannoma.

displaced by the m ass. On precontrast coronal T 1 WI

of MRI. the peripheral portion of the tumor was iso-

and s lightly low 51 which was well enhanced after Gd- DISCUSSION

DTP A a dministration , and the central portion of the

mass was cystic(Fig. 2c.d). Compressed right caver- Calcification is exceedingly rare in schwannomas

nous ICA. desruction of the floor of right middle In 1577 intracranial neoplasms. Martin and Lem-

cranial fossa and obstructive hydrocephalus were m en( 1952)(4) found calcification in 13% of all

a lso well visualized . Angiography showed a very neoplasms. but none in 93 acoustic neurinomas

la rge. extraaxial. slightly h ypervascula r tumor with which they encountered . Ossification is extremely

anterior a nd inferior displacement of the extradural rare. The mechanism of this calcification is unknown.

portion of the right internal carotid artery with open- In the literature . we found only three reports of

ing of the carotid siphon . and abnormal tumor schwannomas with calcification in the head:the

vasculatures derived from the precavernous and one(5) in which there were three cases with calcifica-

cavernous segments ofthe carotid siphon. At opera- tion among 120 collec ted trigeminal schwannomas.

tion. a la rge . enca psulated. solid . firm m ass of the second(6) with one case of calcified schwannoma

Journal of Korean Radiologicai Society 1992 ; 28 (1) : 51 ~55

among three trigeminal schwannomas , a nd the

third(4) with one case report of calcified acoustic

neurinoma consisted mainly of a conglomerate of

dense ca1cification

Schwannoma is a so\itary , encaps비ated tumor

usually attatched to , or surrounded by a nerve and

is almost never associated with von Recklinghausen ’ S

disease or malignant change. Neurites do not traverse

the tumor , and degenerative changes such as cystic

a Iterations or hemorrhagic necrosis a re usually pre

sen t. With \ight microscopy , the schwannoma is an

encaps비ated tumor with a distinctive pattern form­

ed by well developed cylindrical structures (Antoni

type A tissue) which on cross-section produces a

palisading pattern of nucIei about a loose-textured

stroma in which the fibers and cells form no distinc­

tive pattem (Antoni type B tissue). Regressive

changes. incI uding necrosis. cystic degeneration ,

Iipidization and angiomatous cIusters ofblood vessels

with focal thrombosis. are prominent and do not bear

relation to the size or location of the tumor. The An

tomi B pattern is commonly intermixed with the An­

to ni A. but a n e ntire tumor may h ave this

arrangement( 1-6)

While a schwannoma can occur in all age groups.

most individuals are in the 30- to 60- years of age and

only rarely it seen in childhood. Zü \ich ‘ s youngest pa­

tient was 11 years 이d(2). lt is two to four times more

frequent in women. About 25-45% of a ll schwan­

nomas occur in the head and neck. and in this region

the lateral neck is by far the most common site. Our

Case 1 seemed to arise from the l10 0r of the a nterior

carnia l fossa with invasicn into the frontal and

ethmoid s inuses and the orbit because of the vector

of tumor growth.

Acoustic shwannomas comprise 95% of all in­

tracranial schwannomas. Trigemina l schwa nnomas

are a distant second. Schwannomas arising from the

intracranial portion of the trigeminal nerve represent

between 0 .07% and 0.36% ofintracranial tumors a nd

0.8% to 8% of intracranial schwa nnomas. Schwan­

noma may a rise intradurally from the nerve root in

the cerebellopontine angle and Meckel ’ s cave or ex

tradurally from the gasserian ganglion in the middle

cranial fossa. The tumor is centered anteromedial to

the internal a nditory canal. J efferson cIassified these

tumors into three types: a) tumors mainly in the mid­

dle fossa: b) tumors mainly in the posterior fossa: a nd

c) tumors with significant components in both mid­

dle a nd posterior fossae(2 ,5)

Schwannomas range in size from several

millimeters to several centimeters , a nd tend to grow

slowly. producing pain and focal n eruologic symp­

toms only when they are large enough to compress

surrounding structures. Pain and cranial neuropathy ,

re lated to compresssion ofthe nerves in thejuglular

foramen. are the most common symptoms of schwan­

nomas of the head and neck. However , a pa inless

parapharyngeal or neck mass is a typical presentaion

At srgery. the nerve of origin may be identified stret­

ched over the tumor. In these cases the surgeon may

be able to extirpate the lesion while preserving the

nerve. This is in contrast to the n eurofibroma . in

which the nerve is an integral part of the tumor a nd

must be sacrified in order to excise the lesion(2)

Radiographically(5-8). schwannomas remodel ad­

jacent bone structures. so if they occur within the

sinus cavity , differentiation from other lesions in­

cI uding mucocele may be impossible. The diagnosis

of a neurogenic tumor is suggested when a tumor

mass is seen to extend through various fissures and

foramina. CT appearances re f1 ect two major

histologic variations. which ranges from a focal . well­

encapsulated. homogeneous ovoid m ass to a primari­

Iy cystic lesion . About one third ofthe cases enhance

more than muscle on postcontrast CT scans ‘ one

third have attenuation values of muscles. a nd one

third a re primarily cystic. Because of poor vasculari­

ty. th e contrast m edium is not rapidly dissipated

within the vascula r system. The MRI cha racteristics

of schwannomas are those of an intermediate signal

intensity on T 1 WIs and PDWIs. The T2WIs vary ac­

cording to whether the lesion is hig hly cellular (in­

termediate intens ity) or cystic a nd stromal

(nonhomogeneos high intensity ).

Trigemina l schwannomas can cause a shrply

delineated bone defect in the l10 0r of the middle

cranial fossa. erosion of the a nteromedia l part of

pyramid. a nd involvement of the superior orbi tal

fissure. the clinoids , the optic canal ‘ and adjacent

lateral wall of the sphenoid sinus. Bone changes are

infreque ntly seen with trigeminal schwannomas in

the posterior fossa . Although amputation of the

petrus apex is occasionally observed with posterior

fossa schwannomas. f1attening of the posterior sur­

fac e of the perfous apex is more common. Compared

to acoustic schwannomas. they are more prone t。

contain cystic components and are thus more varied

in appearance. On MRI. they typically appear as an

extraaxial. rounded or bilobulated masses expanding

the cavenous sinus and extending over the superior

aspect of the petrous apex into the superior

cerebellopontine angle cistern. ln most cases they are

better localized and characterized on MRI than on CT.

De ne rvation of the affected muscles of mastication

may produce a unilateral decrease in bulk and in­

crease in signal intensity due to increased fat

deposition.

The majority of schwannomas are avascular on

routine a ngiography:only infrequently are they

hypervascular. Angiographic findings in trigeminal

schwannomas include medial displacement of the

carotid siphon. displcement of arterial structures

characteristic of an extraaxial mass. and abnormal

tumor vasculatures derived from the precavernous

and cavernous segments of the carotid siphon.

Although the nerve origin of the tumor could not

be found at operation in our case 2. the tumor seem­

ed to a rise from the trigeminal nerve in the middle

<국문 요약>

Jong Deok Kim , et al : Intracranial Calcified Schwannomas

cranial fossa with extensive tumor growth in all direc­

tions as documented by the radiological findings

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1983 ‘ 344-355 3 . Zulich KJ. Brain Tumors. Their biology a nd

pathology. 3 rd ed. Berlin: Springe r-V erlag .

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4. Ma ncuso AA. Ha nafee WL. Computed tomography

and magnetic resona nce imaging of the head and

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1985:183-184

5. Thomsen J. Klinken L. Tos M. Clinical records

Calcified acoustic neurinoma. J Laryngol Oto July

1984 ‘ 98:727-732

6. McCormic PC , Bello JA ‘ Post KD. Trigeminal

schwannoma. Surgical series of 14 cases with review

of the literature. J neurosurg 1988;850-860

7 . Goldberg R. Byrd S. Winter J . Takahashi M. Joyce

P. Veried appearance oftrigeminaJ neuroma on CT.

AJR 1980;134:57-60

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석회화를 동반한 두개내 신경섬유초종 : 2예 보고

인제대학교 의과대학 진단방사선과학교실

김 종 덕·정 덕 환

신경섬유초종에 있어서 퇴행성 변화인 냥성퇴행과 출혈성괴사는 잘 알려져 있지만 석회화에 대한 보고는 매우 드물다.

저자들은 최근 전뇌와와 중뇌와에서 발생한 각각 1예씩의 석회화를 동반한 신경섬유초종을 경험하여 이들의 방사선학적

소견을 문헌고찰과 함께 보고하는 바이다.

ζ디 -

Int. Symp. on Recent Advances in Diagnostic Imaging and Radiation Radiology venue: Kathmandu , Nepal. contact: Dr. Naresh Prasad , Dep t. Radiology ,

Texas Medical Center, TX 77030 Houston , USA. (Tel: ; Fax: 1992/03/24-2 7

24th International Diagnostic Course venue: Davos , Switzerland. contact: IDKD ,

P.O. Box 224 , CH-8028 Zurich , Switzerland (Tel: ; Fax: 1992/03/28-04

Les Ul trasons De Besancon venue: Besancon , France. contact: Ir. F. Weill , Electroradiologue ,

C.H.U. , Ar. Fleming, 25000 Besancon , France. (Tel: 81 668288; Fax: 81 831493) 1992/03/31-02

Int. Exhibition of Medical Imaging Equipment + 51st Congress Japan Rad. Soc. venue: Pacifico Yokohama, Japan. contact: Secretariat of JMCP

Omuro-Building 5F , 1-6-2 Yushima , Bunkyo-ku , Tokyo 113 , Japan (Tel: 03-5684-0701; Fax: 03-5684-0702) 1992/04/03-05

17th Annual Meeting Soc. of Cardiovascular and Interventional Radiology venue: Hilton Hotel & Towers Washington D.C., USA. contact: Soc. Cardio. Interv. Radiol., Technical Exh. Services ,

2021 Spring Road , s. 600 , IL 60521 Oak Brook, USA. (Tel: 708-5717854 , Fax: 1992/04/04-09

3rd International Congress on Medical U1trasound venue: Istanbul, Turkey. contact: Progress Congressi ,

Via Carlo Conti Rossini 58 , 00147 Rome , ltaly. (Tel: 06-517951 ; Fax: 06-5133044) 1992/04/1 2-15

25th Annual Conf. and Postgraduate Course in Head and Neck Radiology venue: Chicago , IL , USA. contact: Ms. Beth A. Filip , Am. Soc. Head & Neck Radiol ,

2210 Midwest Road , IL 60521 Oak Brook , USA. (Tel: 708-5740220; Fax: 708-5740661) 1992/04/22-26

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