tumefactive Multiple Sclerosis: diagnostic study

TumefactiveMultipleSclerosis(MS) 65

IntroductIon

Multiple sclerosis is an inflammatorydemyelinatingdisorderofCNS,thatmayappearwithavarietyofdif-ferent clinical presentations and laboratoryfindings.TumefactiveMSisatypeofMSwhichischaracter-izedby thepresenceofat leastone lesion≥2cmindiameter1.Radiologically,itpresentsassingleormul-tiplecontrast-enhancedlesions,withco-existingmasseffect andedema≥3mm.Thepresenceofcysticornecroticareasisalsopossible2.

ThecontributionofmodernMRItechniquesinthediagnosis and differential diagnosis of tumefactiveMSisstronglysupportedbythescientificworld.

cASE rEPortS

Case 1: A17-year-oldmalewasreferredtoAHEPAhospital emergency department, with left hemipare-sis and dysarthria. Two similar transitory episodeswere also revealed in his medical history. Cerebro-spinalfluidanalysisrevealedIgGoligoclonalbands,therefore indicating possibleMS.TheMRI showedamass in the right semi-oval center withmediocreedema(Figure1a).Thepatienthadarapidresponsetotheconservativetreatmentwithhighdosesofste-

roids,whichwasconfirmedbytheradiologicalretest(Figure1b).Twoyears later, hewasadmittedagainin the ER, with status epilepticus, right hemipare-sis andwalk disorders.TheComputedTomography(CT) scan only revealed the first lesion in the righthemisphere(Figure1c).TheMRIconfirmedasecondtumefactive lesion in the opposite hemisphere,withspottedenhancement,whilethefirstlesionshowednoenhancement(Figure1d).Thepatientfullyrecoveredaftertreatmentwithsteroids.

Case 2:A65-year-oldfemalewasadmittedtoourhospitalwithacuterighthemianopsia.TheCTcarriedoutafewhoursafterwards(Figure2a),aswellastheMRIcarriedoutafewdayslater,showedalefttem-poral-occipitalmassinthecerebralparenchymawithnon-homogeneous, peripheral, annular enhancement(openringsign)andmediocrecircumcentraledema.However,becauseof thenegative laboratoryexami-nationsandtheadvancedageofthepatient,anintra-cranialmasswasthoughttobethepossiblediagnosis.Asaresult,themasswassurgicallyremoved(Figure2c). However, the histological examination showedperivascular infiltrationbyhistiocellsanddemyelin-ation.Twoyearslater,thepatientwasadmittedwith

Case RepoRt

tumefactive Multiple Sclerosis: diagnostic study considering the differential diagnosis from other brain lesions.

AfroditiHaritanti,EvdokiaKarathanasi,StamatiaPotsi

University Department of Radiology, Aristotle University of Thessaloniki, AHEPA Hospital, Greece

ABStrAct: TumefactiveMultipleSclerosis(MS)ischaracterizedbythepresenceofatleastonelesion≥2cmindiameter,withco-existingmasseffectoredema.Inourstudy,wereviewtheadvancedMagneticResonanceImaging(MRI)techniquesusedinthediagnosisoftumefactiveMS,aswellasthespectrumofdifferentialdiagnosisfromotherbraintumors.WealsopresenttwocasesoftumefactiveMS.Inconclusion,tumefactiveMSshouldalwaysbepartofthedifferentialdiagnosisineachpatientwithradiologicalfeaturesoftumor-likebrainlesions,inordertoavoidunnecessaryinterventionaldiagnosticprocedures.

Key Words: Tumefactivelesions,Multiplesclerosis,MRItechniques.

Corresponding author: Evdokia Karathanasi, Pelias 2 Τ.Κ.:54453 (Toumpa) Thessaloniki, Tel.: +30 2310 919442, Mob: 6947 566035, e-mail: eyhkara@yahoo.gr

66 AristotleUniversityMedicalJournal,Vol.36,Issue2,June2009

left hemianopsia. The CT and theMRI (Figure 2d,e)showedasecondmassintheoppositehemispherewith thesamecharacteristics(openringsign)as thefirstlesion.ThefindingsofMRspectroscopy(Figure3) spoke in favor ofMS; therefore the patient was

treatedconservativelywithsteroidsandshowedsatis-factoryclinicalimprovement,aswellasrestrictionofpathologicalenhancementintheretest(Figure4).

Figure 1.a.AxialT2-weighted imagerevealedamass inthe right semioval centre withmediocre edema. b.AxialT1-weighted image showed important restriction of thedamage.c.AxialCTimageshowedhypointenselesionleftrespectivelywith the first lesion d.TheMRI confirmed asecond tumefactive lesion in opposite hemisphere,whichshowedspottedenhancement,whilethefirstlesiondidnot

showanyenhancement.

Figure 2. a.AxialCTimagerevealedahypodenselefttem-poral-occipitalmass in the cerebral parenchyma.b.Axialcontrast-enhancedT1-weightedimagerevealedalefttem-poral-occipitalmassinthecerebralparenchymawithnon-homogeneous,peripheralannularenhancement(openringsign).c.AxialcontrastenhancedT1-weightedimageafterthesurgicalremovalofthemasswhereappearsthecrani-otomyandthegliosisofbrainrespectively.d,e.AxialCTimage and coronal contrastenhancedT1-weighted imagerevealed a secondmass in opposite hemisphere with thesamecharacteristics(openringsign)ofthefirstlesion.

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TumefactiveMultipleSclerosis(MS) 67

dIScuSSIon

AdvancedMRItechniqueshavebeenestablishedforbetterneuroimmagingevaluationinMS.Inthemag-netization transfer (MTR), which is related to thephenomenonoftransportofmagnetization,demyelin-ationrepresentsaprogressivereductionofratiofromtheperipherytothecentreofthelesion3-5.IndiffusionMRI,MSlesionsappearwithincreasedApparentDif-fusionCoeficient(ADC)reception,incontrasttocere-bralabscesswherereductionofADCisobserved3.InperfusionMRI,MSlesionsshowneitherincreasenordecreaseofrCBF,incontrasttocerebraltumorswhereincreaseofrCBFisobserved3,6.InMRspectroscopy,areductionofNAA,Cr,β,γ-GlxanddetectionofLAC,CHOandlipidsduringtheacutephaseofMS,havebeen reported. On the contrary, during the chronicphaseofMSthereisanincreaseofNAA,Cranddis-appearanceofLACandlipids3,5,7-9.Inourstudy,MR

spectroscopybasedonmeasurementsofmetabolitesβandγ-Glxwasprovenhelpfulinthedifferentialdiag-nosisofMS9.Indeed,thesemarkersincreaseincaseoftumefactiveMS,butnotinaggressiveintracranialmasses(Figure5).

Three major observations were evident in ourstudy.Thefirstwasrelatedtotheperipheral,non-ho-mogenous,annularenhancementoflesion,character-izedas“openringsign”,whichisobservedintume-factive MS10. The enhancement is related to bloodbrainbarrierbreakdown.Nevertheless,experimentaldataalsoreportenhancementofthelesionevenwith

intactbloodbrainbarrierduetomacrophageinfiltra-

tion2.Thesecondobservationconcernsthehistopath-

ological findings; reactive astrocytosiswith atypical

mitotic characteristics, foamy macrophages (myelin

breakdownproducts)andchronicperivascularcellu-

lar infiltrationcausemajordifficulties indifferential

Figure 3.MRSpectroscopyofthepatientwhichconfirmedthediagnosis.

Figure 4. AxialMRIimagesshowedrestrictionofpatholog-icalenhancementoflesionafterdispensationof steroids.

68 AristotleUniversityMedicalJournal,Vol.36,Issue2,June2009

diagnosis fromglioma11.The third observation con-

cernstheprogressoftheunderlyingpathologyandthecorrespondent clinical impact. Evidently despite theradiologicalfeaturesofthelesion,andthepossibilityofmalignancy, itwouldbepreferable toperformanintensivefollowupwithneuroimmagingforthesafe-tyof thefinaldiagnosis rather thanproceedingwiththe treatment such asoperationor irradiationof thelesion.Inaddition,incaseofdemyelinatingdisorderstheresponsetosteroidtherapyisusuallysatisfactory.

The inflammatory demyelinating brain disordersoften imitate intracranial masses. The tumefactiveMS should bemainly differentiated from tumors as

glioma, astrocytoma and lymphoma, from other in-flammatorydemyelinatingdisordersasacutedissemi-natedencephalomyelitis (ADEM)and fromcerebralabscesses11,12.Certain laboratoryfindings, coexistinglesions inneuroradiologyexaminations (eg.cervicalspinalcord)andrapidresponsetocortisonefavortu-mefactiveMS.Inthecasespresentedhere,thedistinctclinicalandradiologicalpresentationsofthesamedis-easeintwodifferentindividuals,wereidentified.Thefirst patientwas successfully treated conservatively,onthecontrarytothesecondonewhounderwentun-necessary surgical operation. In the second case thecorrectdiagnosiswasmadelaterwiththecontributionofMRspectroscopyandthepatientwasthentreatedappropriately. The intracranial masses constitute animportantmedicalproblem.Theroleofmodernimag-ingshouldnotonlybelimitedinanatomicdetails.TheadvancedMRItechniquesallowustoinvestigatebrainfunction;perfusionMRIgivesimportantinformationaboutbloodcerebralflow(rCBF);MRspectroscopyhelpsusmeasurevariousbrainmetabolites.

concLuSIon

In thedifferentialdiagnosisof tumefactivebrain le-sions, the tumefactiveMSshouldalwaysbeconsid-ered. Moreover, the advanced imaging techniquespromiseprecisediagnosticapproach,inordertoavoidunnecessaryinterventionalproceduresforthefinaldi-agnosisanddifferentialdiagnosis.

Abbreviations:ADC: Apparent Diffusion CoeficientADEM: acute disseminated encephalomyelitisCHO: cholineCr: creatineLAC: lactateMRI: Magnetic Resonance ImagingMS: multiple sclerosisMTR: magnetization transfer NAA: N-acetylaspartaterCBF: blood cerebral flow β, γ-Glx: glutamate/glutamine

Figure 5. a.Axial T1-weighted post-contrast MR imageshows a small ring-enhancing lesion in the genu of theright internalcapsule (arrow)andabarelyperceptible le-sionintheleftglobuspallidus(arrowhead).Multipleaddi-tionalsimilarsmallring-enhancinglesionswereidentifiedthroughoutthebrainparenchyma.b.VoxellocalizationforprotonMRspectroscopyoftherightinternalcapsulelesion.c.MRspectroscopyoftherightinternalcapsulelesiondem-onstratesmarkedelevationoftheβ,γ-Glxpeaks(doublear-rows)comparedwithcreatine(peakheight ratio1.1[nor-mal less than 0.5]) compatiblewith tumefactivemultiplesclerosis.ThereisalsomilddecreaseofN-acetylaspartate

andprobablemildpresenceoflactate.

TumefactiveMultipleSclerosis(MS) 69

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ΠΕΡΙΛΗΨΗ:Ωςογκόμορφηορίζεταιηπολλαπλήσκλήρυνσηπουχαρακτηρίζεταιαπότηνπαρουσίαμίαςτουλάχιστονβλάβης,διαμέτρου≥2εκ.,μεσυνοδόφαινόμενομάζαςήοίδημαοποιουδήποτεβαθμού.Στηνεργασίαγίνεταιεκτενήςβιβλι-ογραφικήανασκόπησηστιςνεότερεςMRIτεχνικέςμετιςοποίεςμελετάταιηογκόμορφηπολλαπλήσκλήρυνσηκαιτίθεταιηδιάγνωσήτης.Αναφέρεται,ακόμη,τοεύροςτηςδιαφορικήςδιάγνωσηςτηςπάθησηςαπόάλλεςχωροκατακτικέςεξεργασίεςτουεγκεφάλου.Παρουσιάζονται,επίσης,δύοπεριστατικάασθενώνμεογκόμορφηπολλαπλήσκλήρυνση.Συμπερασματικά,καταλήγουμεστογεγονόςότιπρέπειπάνταναδιερευνάταιηπερίπτωσητηςογκόμορφηςπολλαπλήςσκλήρυνσηςσεκάθεασθενήμεαπεικονιστικάευρήματαχωροκατακτικήςμάζαςτουεγκεφάλουώστενααποφεύγονταιάσκοπεςεπεμβατικέςμέθοδοιγιατηντελικήδιάγνωσηκαιδιαφοροδιάγνωση.

Λέξεις Κλειδιά: Ογκόμορφες βλάβες, Πολλαπλή σκλήρυνση, MRI τεχνικές.

Ογκόμορφη πολλαπλή σκλήρυνση (MS): διαγνωστική μελέτη στο πλαίσιο διαφορικής διάγνωσης άλλων χωροκατακτητικών εξεργασιών του εγκεφάλου.

ΑφροδίτηΧαριτάντη,ΕυδοκίαΚαραθανάση,ΣταματίαΠότση

Εργαστήριο Ακτινολογίας, Ιατρικής Σχολής, Αριστοτελείου Πανεπιστημίου Θεσσαλονίκης, Nοσοκομείο ΑΧΕΠΑ

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