Turkish Neuiosurgery 4: 165· 168. 1994 Atabay: IntradipJoic Epidemioid

Giant Primary Intradiploic Occipital Bone Epidermoid Tumour:A Case Report

HAYATI ATABAY. SAM I BARDAKCL YUSUF ERSAHIN, ÜMIT BAYOL

Departments of Neurosurgery (HA. SB)and Pathology (ÜB)Tepedk Sodal Security Hospital.and Department of Neurosurgery (Y.E.)Ege University Medical SchooL. Izmir. Turkey

Abstract : A case of giant intradiploic epidemioid cyst which erod·ed both tables of the skull and expanded espedally to the posteriorfossa is presented. Despite the large size of the lesion. the patienthad only mild symptoms and left cerebellar signs.

INTRODUCTION

Epidermoid and dermoid tumours of the centralnervous system are rare, benign and slow - growinglesions (13.17.18).The reported incidence is between0.7-1.8% of all intracranial tumours (1.2.14,16.18).They devdop from displaced dorsal midlineectodermal rest cells between the 3th and the 5th

gestational weeks during the neural tube dosure(1.2.3,9.11, 14.18). They mayaiso devdop from theimplantation of skin in deeper tissues by repeatedlumbar puncture. ventricular taps and inadequatesuturing of scalp laceration (9.13).Epidermoid cystsgrow because of the gradual accumulation ofkeratinand cholesteroL. desquamation products of epithelialcells in time (1,9.11,18).Symptoms may appear at anyage but are commonly seen in adulthood (3.6.8).These tumours can be located anywhere in thecranium.

Giant intradiploic epidermoid tumours (GIDET)are extremely rare. We were able to find only threecases in the posterior fossa in the English literature(7.11.12).

These slow growing. giant lesions are benign and can be totallyremoved without any defidt.Key Words : Epidemioid tumour. Ocdpital bone. Intracranialhypertension

CAS E REPORT

A 51-year old man was admitted to the Depart­ment of Neurosurgery. Tepecik SSKHospital. on May5, 1993. He had noticed a nontender subcutaneous

swelling in the left occipital area accompanied byheadache, blurred vision. gait disturbance. bladderincontinence and global dementia in the last 3months. On admission. examination revealed a sub­

cutaneous swelling (8 cm in diameter) in the left oc­cipital region. He was alert. Minimalleft cerebellarsin gs (dysmetria and dysdiadochokinesia) andpapilloedema were detected on neurological ex­amination.

Skull plain x-rays displayeda well-circumscribedradiolucent defect with sderotic borders measuring8x8 cm in the left occipital bone (Fig 1). Computeriz­ed tomography (CT) reve ale d alarge. well­circumscribed and extraaxial hypodense tumour inthe left posterior fossa. The inner skull table waseroded totally and the outer table was very thinand eroded. The lesion contained areas ofcalcification and showed no contrast enhancement.

CT also showed the compression of the occipital

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ham of the left lateral and the 4th ventricles

which resulted in moderate supratentorialhydrocephalus (Fig. 2). The tumour was extendingtowards the foramen magnum. Angiographywas planned. Unfortunately. transfemoralcatheterization was not successful due toatherosclerosis.

Fig. 1 : Lateral view of the plain X-ray film of the skul1. showingthe drcumscribed radiolucent deEea with sderotic borders.

Fig. 1 : CT scans showing alarge. well-drcumscribed hypodenselesion. compressing the left ocdpital hom and the 4th ven­tride. Note the calcification in the mass and mild ventricwardilatation.

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The patient was operated on in sitting pasition.Bone was found to be eggshell-thin. Sernisolid cheesymateriaL. causing compressian of the cerebellar duraand elevation of the tentorium was removed totally(Fig.3).After total removal. as the cerebellar dura didnot expand and refill the epidural cavity. the spacewas filled with saline before the closin&-process.

Fig.3 : Operative photograph showing the tumor cavity after total

resection. Note the eggshell-thin bone. tagged by sutures.

Pathological examination confirmed epider­moid tumour. The symptoms of the patient resolv­ed in a week. Postoperative CT sean. one week aftersurgery revealed total removal of the tumour andimprovement of the hydrocephalus and alsa disclos­ed same air and epidural fluid in the cavity (Fig. 4)The patient was discharged without any neurologicaldefidt.

Fig. 4 : Postoperative CT seans showing total removal of the tumor

and improvement of the hydrocephalus. Note air and Eluidin the epidural space.

Turkish Neurosurgery 4: 165 - 168. 1994

DlSCUSSION

Epidermoid tumors can be loeated intradurally orextradurally in any part of the eranium. Theyare rareand approximately consist of 0.7-1.8% of all braintumors (1.2.14.16.18).Extradural lesions comprise on­ly 25% of the total intraeranial epidermoid tumorswhich may oeeupy the sealp and the diploe (4.7.17).Theyare commonly seen as an inddental finding onradiographie examination of the skull (4.17).Plain x­ray films of the skull disclose the epidermoid eyst asan osteolytic lesion with well-defined seleroticmargins (3.6).

In 1838. Mller (io) was the first to deseribe adiploie epidermoid eyst of the skull. According toCiagetta et al (3) a total 223 eases had been reportedup to 1990. Only a few cases of GlDET have beendescribed in the literature and three of them are

loeated in the posterior fossa (7.11.12) (Table 1).

Atabay: 1ntradipIoic Epidermoid

eaused global dementia. gait disturbanee and blad­der ineontinenee which resolved after operation.

In our ease. preoperative CT sean revealed theobstruetion of the fourth ventriele and moderate

hydroeephalus. Tumor was not reeognized at thelevel of the confluenee of the venous sinuses. Unfor­

tunately. we were not able to demonstrate the paten­ey of the toreular Herophili in our case. As Rengacharyet al (ii) pointed out. we think that obstruetivehydroeephalus and venous congestion eaused bythe oeelusion of the major venous sinuses areprimarily responsible for intracranial hypertension.Since these are very slow growing tumors. eollateralvenous dreulation can be sufficient if toreular

Herophili is open.

Total removal of the tumour with its capsule isessential. because these tumors are not radiosensitive

and have a high tendeney to reeur.

Table i :GIDET of Posterior Fossa

Authors

YearAge/SexSideSizeHydrocephalus Occlusion ofIntracranial

torcular Herophilihypertension

Rengachary et al.

197862/Mmidline13x13 cm+ ++

Rubin et aL.

198927/Mmidline3x3.5 cm- ++

Grudi et aL.

199047/Mright5x7 cm - --Atabay et al

199451/Mleft8x8 cm +unknown+

M: male. +: present. -: absent.

As in our ease. GlDETs usually destroy bothtables of the skull. They may expand externally andeause masses in the scalp or fadal region. or internalexpansion may result in the eompression of in­traaanial contents (9.15,17).Sinee these are extremelyslow growing tumours. there may be no clinicalevidenee apart from a painless swelling or palpablebone defect und er the sealp for a long time. Obstrue­tive hydrocephalus and/or obstruction of the largevenous sinuses. due to intracranial hypertension caneause headache which is the most common symp­tom (3.4. 5.11.12). However Guridi et al (7)reporteda case of a GlDET in the posterior fossa without in­traaanial hypertension. In their case, hydrocephalusand obstruetion of the toreular Herophili had notbeen identified despite its large size and there wasno headache or other neurological symptoms. Con­vulsion and focal neurologic signs may be recogniz­ed. As in our case, obstructive hydrocephalus also

These is also the rare possibility of caranomatousdegeneration (1.3.4.8.11.17.18). Total removal of thetumor can be easily aecomplished and is assodatedwith good outcome, despite its large size.

Correspondence : Hayati AtabayAli çetinkaya Bulvan No:68-22Alsancak. izmir. Turkeyphone: 232 - 463 85 24

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