Turkish Neurosurgery 4: 34 - 37. 1994 Bagdatoglu: Lipomas of The Corpus Ca110sum

Lipomas of The Corpus CallosumA Report of Four Cas es

HÜSEYIN BAGDATOGLU. FARUK ILDAN. MAHMUT DOGANAY. ISKENDER GÖÇER.

ERDAL ÇETINALP ASKIN KARADA YI

Çukurova University. School of Mediane Dept of Neurosurgery (HB. FI. MD. IG. EÇ. AK). Adana. Türkiye

Abstract : Lipomas of the corpus callosum are rare congenital con­ditions. These lesions are often asymptomatic but may presentas epilepsy. hemiplegia . dementia or headache. Computerizedtomography and magnetic resonance imaging make the diagnosisof lipomas feasible at any site of the intracranial space. becauseof very low density attenuation value s on computerizedtomography and the short Tl and T2 on magnetic resonance.

INTRODUCTION

Lipomas occur in most parts of the body, but in­tracranial lipomas, which are extremely rare. aredevelopmental in origin. Intracraniallipomas main­ly occur in the region of the corpus callosum, par­ticulady in the rostrum, as first described byRokitansky in a case of necropsy [Cited in (2)).Although 25 % to 30 % of intracraniallipomas arelocated in the corpus callosum, they make up 5 % ofall corpus callosum tumours (i 7). Callasal lipomasmay be frequently associated with other disturbancesincluding absence of corpus callosum, myelomen­ingacele and spina bifida (i). Although computeriz­ed tomography (CT) has been of great help in thediagnosis of these lesions (20) ,recently magneticresonance imaging (MRI)has provided highly visibleimages of the corpus callosum . and therefore is be­ing used for the diagnosis of callasal lipomas andother diseases of this structure (5,6).

Neurological manifestations of lipomas are notspecillc and consist of severe headache, disturbancesin mentian, seizures and dissociation in behaviour

A direct surgical approach is very rarely necessary in these lesions.Four cases with lipoma of the corpus callosum diagnosed by com­puted tomography are presented and the literature is reviewed.Basic diagnostic considerations and therapeutic options arediscussed.

Key Words: Computerized tomography. Corpus callosum.Lipoma. Magnetic resonance imaging.

(9,i 9). Lipoma of the corpus callosum does not lenditself to surgical cure in cases with seizures since an­ticonvulsant therapy usually results in remission ofthe seizures.

We report in this paper four cases with corpuscallosum lipomas and discuss the anatomoclinicalfeatures. histological characteristics, the radiologicaldiagnosis and therapeutic modalities of these lesions.

CASE REPORTS

Case I

This 7-month-old boy had generalized seizures for4 weeks before admissian. There was no neurologicaldeficit. A CT scan showed multiple low-densitytumours of the corpus callosum (-78H.U)lying withinboth lateral ventricles along with peripheral calcillca­tion (+ i23 H.U). CT scan with attenuation measure­ments established the diagnosis oflipoma of the cor­pus callosum in combination with lipomas of thechoroid plexus of both lateral ventricles (Fig.i). Nooperation was performed.

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Turkish Neurosurgery 4: 34 - 37. 1994

Fig. 1 : Case 1. Combination of lipoma of the corpus ea110sumandlipomas of the choroid plexus of both lateral ventndes.

Case II

This 60 year old man had complained ofheadache for one year. A CT sean showed ahypodense lesion (-38 H.U) beginning from the cor­pus callosum and descending into the right ambientcistem with agenesis of the corpus callosum (Fig.2).No operation was contemplated.

Fig.2: Case ll. Lipoma of the eorpus eallosum deseending to theambient dsterm.

Case III

This 36-year-old man had a one year history ofoccipital headache. Neurological examination reveal­ed no abnormality. CT sean showed regular low den­sity (-55 H. U.) involving the corpus callosum fromthe genu through the body into the splenium (Fig.3).This lesion was presumed to be alipoma due to at­tenuation measurements and no operation was per­formed.

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Bagdatoglu: Lipomas of The Corpus Callosum

Fig. 3: Case 111. Axial CT sean showing a low hypodense lesioninvolving the eorpus ea110sumfrom genu through the bodyinto the splenium.

Cas e LV

This 3-year-old boy suddenly complained ofheadache. nausea and vomiting for two days beforeadmission and seizures beginning one year ago. ACT sean revealed a lobulated mass of extremely lowdensity (-90 to -110 H.U.) in the corpus callosum(FigA). The seizures were controlled with medicationand no operation was contemplated.

Fig. 4: Case IV. Large lobulated lipoma in the eorpus eallosum.

DlSCUSSION

Most authors have hypothesized that intraaaniailipomas originate from fat cells present in the lep­tomeninges or primitive pial cells due to maldevelop­ment (15).This theory is supported by Mattem et al(13) since the common location of lipomas in somecistemal space which has a much amount of lep­tomeninges and these regions correspond to the siteof flexion of neural tube.

Turkish Neuwsurgery 4: 34 - 37, 1994

Intracranial lipomas are most frequently locatedin the region of corpus callosum since they often arisefrom the midline cerebral astems. particularly thecallosal astem (3.18). Other common locations arethe region of the ambient astem. the tuber dnereumand th quadrigeminal plate (7.10). Lipomas of thelateral cistems are extremely rare and a few caseshave been described in the cerebellopontine angle(8.16) or in the sylvian fissure (4.11).

In the pre-CT era. intracranial lipomas were rare­ly encountered . Peripheral caleification of lipoma inplain skull x-rays are reported to be diagnostic (18).but were nonspeeific in all our cases. This entity wasmore often diagnosed during the life time of the pa­tient by the clinicians with the advent of CT scann­ing. Recently MRI provides highly visible images ofthe intracranial lipoma particularly for the callosallipomas (1.5).The CT characteristics oflipomas of thecorpus callosum were first described by NewandScott (14) in 1975. A homogeneous low density areawith attenuation values between -60 and -200 H.U.

no contrast enhancement. regular margins and oftenlinear caleifications in the surrounding area are themain characteristics of this lesion on CT scan.

Although the CT attenuation values of fatty tissueranged between -38 and -1l0 H.U. in our series. den­sity of the lesion in the second and third cases whichwas -38and -55 H.U. respectively. was considered tobe due to the partial volum e effect of peripheralneural tissue around the tumour. as reported byKazner (12). This partial volum e effect generally oc­curs in lipomas smaller than 25-30 mm in diameter.

Intracranial lipomas commonly show short Tland T2 with high intensity region s in Tl-weightedand a decrease in T2-weighted images. MRI is a pro­cedure of choice in the evaluation of corpus callosumlipomas for its capacity to obtain direct coronal im­ages without reconstruction (1.5). Furthermore MRsignals for lipomas are specific and usually allow acorrect diagnosis.

In the differential diagnosis of these lesions. le­sions with a fatty component. such as epidermoidcysts. dermoid cysts. teratomas. myelolipomas.angiolipomas should be considered. Dermoid cystsusually present as less homogeneous lesions on CT(12) and MR1 (15) since they tend to show caleifica­tion and contain hairs in the cyst. Epidermoid cystscontain a high degree of keratin crystals and usallyshow low attenuation values mimicking those of CSF

Bagdatoglu: Lipomas of The Corpus Callosum

on CT scan. Finally. teratomas which contain varioustype of tissue such as adipose. cartilage. muscle andbone would therefore vary in both CT attenuationand MRI relaxation parameters.

Lipomas of choroid plexus combined with lipomaof the corpus callosum similar to the first case in ourseries were frequently mentioned in the earlyneuropathological literature (12).

Although most intracranial lipomas are asymp­tomatic and are diagnosed during neuroradiologicalinvestigations. some patients have neurologicalsymptoms. Callosal lipomas show clinical presenta­tion in alinost half of the cases. In symptomatic cases.the most common symptom is epileptic seizure (50-60%) which can be attributed to interhemisphericdisconnection (9).Epilepsy observed in the first andfourth cases in our series was probably due to sucha disconnection. Some patients may show mentaldeficiencyand slightly psychic retardation due toassociated malformations such as callosal agenesisor hemispheric atrophy. The occurrence of focalneurological signs is exceptional and limited to somecallosal lipomas with hemiparesis.

A direct surgical approach is rarely indicated incallosal lipomas. since theyare slow-growing lesionsand rarely reach a size sufficient to cause a mass ef­fect. Complete removal of the lesion in this locationis almost impossible because of the firm adhesionsbetween the collagenous capsule and the brain andthe high vascularity of the tumour. Furthermore. theclose relationship of the anterior cerebral arteries tothe lesion is another important difficulty for surgery.Surgical management of hydrocephalus may benecessary if pressure symptoms or progressivedementia are present,

We believe that the surgical indications forremoval of a lipoma of the corpus callosum shouldbe carefully and cautiously considered since it is abenign. slow growing lesion. most patients areasymptomatic and epilepsy .which is the commonestsymptom that can not be cured by surgery.

Correspondance: Dr. Hüseyin Bagdatoglu

Çukurova University Faculty of Mediane

Department of Neurosurgery

Balcali, Adana - TürkiyePhone: 324 - 338 60 60

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Turkish Neurosurgery 4: 34 - 37. 1994

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