Journal ofNeurology, Neurosurgery, and Psychiatry, 1976, 39, 1179-1185

Lipoma of the corpus callosumD. WALLACE 1

From the Neurosurgery Department, Hospitalfor Sick Children,Great Ormond Street, London

SYNOPSIS Lipoma of the corpus callosum is a rare congenital condition, often asymptomatic, butwhich may present as epilepsy, hemiplegia, dementia, or headaches. This paper reviews the conditionand reports the only two cases which are known to the Hospital for Sick Children, Great OrmondStreet, London. The second case demonstrated the value of computerised axial tomography (EMIscan) in making the diagnosis and showing associated anomalies.

Lipomas occur in most parts of the body, but intra-cranial lipomas are exceptionally rare. Lipoma of thecorpus callosum was first described in 1856 by Roki-tansky who discovered a case at necropsy. It was notuntil 1939 that the first diagnosis of the condition wasmade in life. The two cases reported below werediagnosed after radiological investigations. As is thecase with other lipomas, lipoma of the corpus cal-losum may be asymptomatic or may produce a num-ber of distressing symptoms. Unlike other lipomas,lipoma of the corpus callosum does not lend itself tosurgical cure.

CASE 1

J.T., a girl born on 9 March 1944, was slow to passher motor milestones. At 14 months she had a focal,right-sided seizure, with loss of consciousness, incon-tinence, and post-ictal right hemiplegia. She did notwalk until 24 months and had a hemiplegic gait. At2 years 3 months of age, there was a second fit. Adiagnosis of pinealoma was made. Three years latershe had an attack of status epilepticus lasting 48hours, followed by coma for two days. On regainingconsciousness, she was severely retarded and aphasic.The aphasia persisted. She resumed walking over thenext three weeks. In 1949 she was reinvestigated anda diagnosis of 'tuberculoma of the brain, withcalcification' was made. She was treated withanticonvulsants. In 1954, she was admitted to theHospital for Sick Children for further study. She hadbeen free from fits for six years.

I Address for reprint requests: Mr D. Wallace, c/o Neurosurgical Unit,Royal Children's Hospital, Parkville, Melbourne, Victoria, Australia.(Accepted 12 July 1976.)

On examination in 1954 there was severe mentalretardation. Speech was limited to six words. Thefundi and visual fields were normal. There was mildright facial weakness and a right spastic hemiplegia.The plantar responses were equivocal. On skull radio-graphy the left hemicranium was smaller than theright. The skull was small, and the vault thick. Calcifi-cation was present, deep in the frontal region, and theanteroposterior half-axial projections showed thetypical configuration of a lipoma of the corpus cal-losum. Bilateral carotid angiography showed that theanterior cerebral arteries joined to form a commontrunk which divided into callosomarginal and peri-callosal arteries. The pericallosal arteries were large,tortuous, and passed straight through the lesion. Thecallosal vessels were displaced to the left of the mid-line, suggesting some degree of left hemiatrophy ofthe brain. A lumbar pneumoencephalogram showeduniform dilatation of the left lateral ventricle andwidened sulci over that hemisphere. The right lateralventricle was of normal size. The anterior horns andbodies of the lateral ventricle were displaced laterallyby the lipoma. Agenesis of the splenium of the corpuscallosum was noted.

Operative intervention was thought to be contra-indicated. She was discharged home, and followed upregularly as an out-patient. She remains well thoughseverely dysphasic, and attends a school for the handi-capped, where she takes part in swimming and horse-riding.

CASE 2

G.S., a 6j year old boy, on 21 September 1974 sud-denly complained of headache and nausea, andvomited twice. Several hours later he was found in aconfused post-ictal state. He was admitted to hospital

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where he had a left-sided fit. He was given anticon-vulsants. Next morning a dense left hemiplegia wasnoted and he was transferred to the Hospital for SickChildren.On arrival he was drowsy, disorientated in time,

with marked neck stiffness and a positive Kernig'stest. There was left upper motor neurone facial weak-ness, and a flaccid left hemiparesis. Tendon reflexeswere normal, and the plantar reflexes flexor. Next dayhe improved and a left homonymous hemianopia wasdemonstrable. Skull radiographs showed an ovalshaped area of calcification enclosing an area ofradiolucency in the anterior region of the corpuscallosum, thought to be pathognomonic of a lipomaof the corpus callosum (Fig. 1). The left side ofthe skull vault was expanded and thinner than theright. The lipoma was slightly to the right of themidline and the crista galli was deviated to theright, consistent with the presence of right cerebralhemiatrophy. A right carotid angiogram with crosscompression showed a single, grossly enlarged,anterior cerebral artery, with a curve of longerradius than usual (Fig. 2). It divided into twopericallosal and callosomarginal branches. The peri-callosal vessels coursed through an avascular space-occupying lesion in the region of the genu of thecorpus callosum and posterior to it. The internalcerebral vein was abnormal in shape. The anteriorportion appeared depressed and pushed backwards.In the venous phase the lateral ventricles were dilated.The EMI scan (Fig. 3) from the National Hospital,Queen Square (reported by Dr J. Gawler) showed theintracranial anatomy to be grossly abnormal. In themid-frontal region there was a well-defined andsmoothly marginated area, of density correspondingto fat. The lesion measured, at maximum, 4 cm in theanteroposterior plane, 3 cm in width, and was sym-metrically disposed with respect to the midline.Posterosuperiorly, the lesion had paired processeswhich extended backwards in a symmetrical fashion,and these processes were separated by a thin bandfrom paired symmetrical fatty cysts, each about 1 cmin diameter. The anterior aspect of the midline lesionwas capped by a rim of calcification. The frontal hornsand anterior parts of the bodies of the lateral ven-tricles could not be identified. On the right the trigoneand occipital horn were dilated. On the left there wasmassive porencephalic enlargement of the ventricle,so that the trigone and occipital horn appeared tooccupy the posterior half of the hemicranium. Theleft temporal horn was also quite dilated. The thirdventricle, which extended backwards from the regionof the fatty lesion, was dilated but lay in the midline.Posterior fossa scans showed a normal fourthventricle. The skull was asymmetrical, the lefthemicranium being larger than the right, and there

was parieto-occipital bulging over the enormouslydilated posterior segment of the left lateral ventricle.He was treated with anticonvulsants and physio-

therapy. His conscious state rapidly improved, andhe became euphoric and excessively friendly. He hadmarked disorientation in time and space. Speech wasnormal. There was astereognosis and left-sidedsensory inattention. The left homonymous hemiano-pia remained. There was a mild residual left facialweakness with mild left spastic hemiparesis. Thetendon reflexes remained symmetrical and the plantarresponses were flexor. He continued to improve andwas discharged home on anticonvulsants. Out-patientreviews have revealed further improvement of thehemiparesis.

DISCUSSION

Lipoma of the corpus callosum, in one series,occurred only four times in 5000 necropsies(Vonderahe and Niemer, 1944). The first case dis-covered at necropsy at the Johns Hopkins Hospitaloccurred after 23 813 consecutive necropsies (Patel,1965). Thirty cases were reported by List and Everett(1946) (28 of these from the literature and two oftheir own). Fifteen additional cases were reported byNordin et al. (1955). At the time of the survey byZettner and Netsky in 1960 there were 59 casesreported in the literature of which 48 were diagnosedat necropsy or confirmed by surgical intervention.Patel (1965) reviewed 72 cases and reported one newcase, Meyer and Leimbach (1970) collected a total of70 cases recorded to 1969. Since 1969 there have beenfurther sporadic case reports (Jayam et al., 1969;Bromowicz, 1970; Larsen and Stiris, 1970; Arseni andMaretsis, 1972; Craddock and Riddervold, 1972;Danziger, 1972; Sukthomya and Menakanit, 1973).The consensus of opinion concerning the aetiology

of lipoma of the corpus callosum is that it is acongenital, hamartomatous condition (Cooper andVon Hagen, 1962). It has been regarded as an exampleof 'cerebral dysraphism', the term dysraphism refer-ring to the midline defects caused by imperfectclosure of the neural tube. The dysraphic concept issupported by the occurrence in some of the reportedcases of other dysraphic disturbances-for example,agenesis of the corpus callosum-occurring in 48%of cases (Zettner and Netsky, 1960), spina bifida andmeningomyelocoele (Patel, 1965). However Zettnerand Netsky (1960), in their most detailed accountof normal and abnormal development of the corpuscallosum, and the possible modes of origin of lipomasof the corpus callosum, pointed out that the com-monest associated dysraphic disturbance, agene-sis of the corpus callosum, occurs in only 48 % ofcases, and concluded that dysraphism was not the

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FIG. 2. Case 2. Lateral and AP carotid angiograms showing a large single, stretched, anterior cerebralarterypassing through the lipoma.

FIG. 3. Case 3. EMI scan showing the anteriorly placed lipoma of corpus callosum, calcification aroundits surface, hydrocephalus, and porencephaly of the left lateral ventricle.

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cause of the lipoma. They believed that the lipomaand the agenesis of the corpus callosum wereproduced by two distinct pathological processes-namely, meningeal maldifferentiation and dysraphism-and that these two processes were possiblygenetically related.

MACROSCOPIC APPEARANCES

The size varies from small nodules, less than 1 cmdiameter, to large masses. There is usually a dense,collagenous capsule, adherent to adjacent brain.The anterior cerebral arteries usually traverse thelength of the tumour and do not deviate significantlyfrom their normal courses. As in the two casesreported here, the anterior cerebral artery is oftenpresent as a single enlarged vessel traversing thetumour, and dividing into pericallosal and calloso-marginal vessels (Danziger, 1972). The vessels mayshow considerable irregularity ofcalibre. The lipomasare often highly vascular. There may be an associatedsubcutaneous lipoma at the vertex, connected to thelipoma of the corpus callosum by a slender stalkwhich passes through a skull defect.

MICROSCOPIC APPEARANCES

Microscopically the lipoma consists of typicaladipose tissue cells, with a variable amount ofcollagen, often obvious at points of contact withnervous tissue, which may penetrate brain tissue inassociation with blood vessels. Ganglion cells andglial elements may be present. Small accretions ofcalcium occur within the capsule of the lipoma, inthe lipoma itself, or in the surrounding brain tissue.The presence of bone has also been described(Rubenstein, 1932). The curvilinear calcification isprobably in the surrounding brain tissue (Patel,1965). There are usually numerous large bloodvessels coursing through the tumour.

ASSOCIATED FEATURES

The commonest associated anomaly is agenesis ofthe corpus callosum (48 % of cases according toZettner and Netsky, 1960). The agenesis may affectpart or all of the corpus callosum (Patel, 1965).There may be associated cerebral hemiatrophy, aspresent in both cases. Associated structural mal-formations of the anterior cerebral artery aredescribed above, as are associated dysraphicdisturbances. Other associated anomalies includewebbed toes, cleft lip, mongolism, funnel chest,facial asymmetry, high arched palate, cardiacventricular septal defect, agenesis of the cerebellarvermis (Zettner and Netsky, 1960), pituitary tumour,and acoustic neurofibroma (Patel, 1965). Associatedintracranial lipomas, most commonly in the choroidplexus of the lateral ventricle, have been reported.

There may be hydrocephalus or porencephaly. Therehas been a recent report ofthe condition in associationwith muscular dystrophy (Jayam et al., 1969).

PRESENTING FEATURES

Approximately 50% of cases are asymptomatic.The commonest presentation is epilepsy, either grandmal or petit mal. Headache, vomiting, hemiplegia,and vertigo may occur. There may be mentalretardation or emotional lability. The origin of theepilepsy in this condition is not clear. One theoryadvanced is that the invasion of cerebral cortex bythe collagenous capsule sets up an irritative focus,producing epilepsy in the way that brain scarringsupposedly produces post-traumatic epilepsy. Theepilepsy does not seem to be related to local pressure,as there are no associated signs of pressure atrophyin nearby brain (Patel, 1965). Papilloedema is a rareoccurrence, described in two previous cases (Nordinet al., 1955; Patel, 1965) in neither cases was itsoccurrence readily explained. Visual field defectswere noted in case 2 above.

RADIOLOGY (Fig. 1)The plain skull radiographic findings are diagnostic(Sosman, 1946). In typical cases there is a radiolucentzone in the frontal region, often comma shaped; this issurrounded by curvilinear calcification along itslateral margins. The lesion is usually symmetricallydisposed with respect to the midline (Taveras andWood, 1964). Unilateral calcification is sometimesseen (Craddock and Riddervold, 1972). While the cal-cification is usually in the form of linear fine specklingalong the margins of the tumour, it may occasionallyoccur in large accretions ofvarying sizes, sometimes aslarge as 1.5 cm (Patel, 1965; Larsen and Stiris, 1970)and may lie in the central part of the lesion (Patel,1965). Deviation of the crista galli with asymmetry inshape and thickness of the skull vault, may indicateunderlying hemiatrophy of the brain.Pneumoencephalography may show hydrocephaly,

evidence of agenesis of the corpus callosum,symmetrical separation and distortion of the anteriorhorns and bodies of the lateral ventricles by thelipoma. There may be little visualisation at all of theanterior horns of the lateral ventricles; there may bedilatation of the foramina of Monro and the thirdventricle. The third ventricle may be displaced by thelipoma or elevated in association with agenesis of thecorpus callosum. A porencephalic cyst may bepresent.

Carotid angiography may show the anteriorcerebral vessel or vessels, often enlarged, or thepericallosal vessels passing through the lesion. If theanterior cerebral artery is single it divides into

D

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pericallosal and callosomarginal vessels. There maybe evidence of an avascular space-occupying lesionin the frontal region, or a fine pathological circulationmay be seen. There may be angiographic evidence ofhydrocephalus. The callosal vessels may be displacedfrom the midline when hemiatrophy is present.The EMI scan will be diagnostic in this condition,

as it may demonstrate that the density of the lesioncorresponds to that of adipose tissue and that thereis associated calcification. The EMI scan is mostuseful in defining associated anomalies such ashydrocephalus, porencephalic cyst, associatedlipomas, and vault asymmetry.

MANAGEMENT

If the condition is detected accidentally there is notreatment. If seizures have occurred, anticonvulsantsshould be given because of the risk of recurrentepilepsy. Surgery has little place in the managementof the condition. Surgical management of hydro-cephalus could conceivably be necessaiy if pressuresymptoms or progressive dementia occurred. Surgicalremoval of the lipoma is unattractive, and there is adismal record of surgery in this group of patients.Zettner and Netsky (1960) reported the results ofsurgery in 16 cases, in which there were 10 deaths,and three cases in which the clinical state wasworsened. In the six survivors, removal was incom-plete in all but one. In onlytwo cases was the recoveryuxneventful, and only one patient was improved byoperation. Since that article was published, twofurther cases of postoperative death have been re-ported (Patel, 1965; Sukthomya and Menakanit,1973). The close relationship of the anterior cerebralvessels to the lesion makes damage to these vessels areal operative hazard. In the case reported bySukthomya and Menakanit, (1973) death was pre-ceded by a state ofakinetic mutism which followed thetying off of the anterior cerebral vessels. Firm ad-hesion between the collagenous capsule and biain to-gether with the high vascularity of the tumour add tothe surgical hazard. The necessity for removal of alipoma of the corpus callosum must be seriouslyquestioned, since it is a non-malignant, non-progressive lesion, and some patients live to old age,trouble-free, untreated. Epilepsy, the commonestsymptom produced by lipomas of the corpuscallosum is unlikely to be relieved by surgery.

It is evident that the EMI scan is the least traumaticmeans now available of investigating the patient witha lipoma of the corpus callosum.

I thank Mr Kenneth Till and Mr Norman Grant(Neurosurgical Department of the Hospital for SickChildren, Great Ormond Street, London) for

permission to report their cases; Dr J. Gawler (theNational Hospital, Queen Square, London) for theEMI scanning reports, and Dr J. Bull (Director,Department of Radiology, National Hospital, QueenSquare, London) for permission to report the EMIscan; Dr R. D. Hoare (Consultant Neuro-radiologist,Hospital for Sick Children, Great Ormond Street,London) for the radiological data.

REFERENCES

Arseni, C., and Maretsis, M. (1972). Liporna of corpuscallosum (in Rumanian). Neurologia, Psychiatria,Neurochirurgia, 17, 15-20.

Bromowicz, J. (1970). A case of lipoma of the corpuscallosum (in Polish). Neurologia, NeurochirurgiaPolska, 4, 739-743.

Cooper, W. C., and Von Hagen, K. 0. (1962). Lipoma ofcorpus callosum. Bulletin of the Los Angeles Neuro-logical Society, 27, 39-44.

Craddock, W. E., and Riddervold, H. 0. (1972). Uni-lateral calcification in a lipoma of the corpus callosum.Journal of the Canadian Association ofRadiologists, 23,192-194.

Danziger, J. (1972). Agenesis of corpus callosum withazygos anterior cerebral artery, a lipoma, and porence-phalic cyst. South African Medical Journal, 46, 739-741.

Jayam, A. V., Banerji, A. P., and Lalitha, V. S. (1969). Acase of muscular dystrophy with probable lipoma of thecorpus callosum. Neurology (Bombay), 17,85-88.

Larsen, J. L., and Stiris, G. (1970). Lipoma of the corpuscallosum with atypical calcification. British Journal ofRadiology, 43,576-577.

List, J. F., and Everett, M. (1946). Lipoma of the corpuscallosum: a clinico-pathologic study. American JournalofRoentgenology, 55, 125-134.

Meyer, T. L., and Leimbach, W. (1970). Lipoma of thecorpus callosum: report and review. Ohio MedicalJournal, 66,492-495.

Nordin, W. A., Tesluk, H., and Jones, R. K. (1955).Lipoma of the corpus callosum. Archives of NeurologyandPsychiatry (Chic.), 74, 300-306.

Patel, A. N. (1965). Lipoma of the corpus callosum. Anon-surgical entity. North Carolina MedicalJournal, 26,328-338.

Rokitansky, C. (1856). Lehrbuch der PathologischenAnatomie, vol. 2, pp. 468. Braumueller: Vienna.

Rubenstein, B. G. (1932). Ueber einen Fall von Unvoll-staendig Tehlendem und durch Fettge webe ErsetztemBalken. FrankfurterZeitschriftfur Pathologie, 44, 379.

Sosman, M. C. (1946). Discussion of papers by A. P.Echternucht and J. A. Campbell. Midline anomalies ofbrain. Radiology, 46,119.

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Sukthomya, C., and Menakanit, V. (1973). Lipoma of thenervous system. Report on 2 cases. AustralasianRadiology, 17, 256-260.

Taveras, J. M., and Wood, E. H. (1964). DiagnosticNeuro-Radiology, 2nd edn. pp. 1-213. WilliamsWilkins: Baltimore.

Vonderahe, A. R., and Niemer, W. T. (1944). Intracraniallipoma. A report of 4 cases. Journal ofNeuropathologyand Experirnental Neurology, 3, 344-354.

Zettner, A. and Netsky, M. (1960). Lipoma of the corpuscallosum. Journal of Neuropathology and ExperimentalNeurology, 19,305-319.

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