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CASEREPORTOpenAccessExtra-gastrointestinalstromaltumorofthepancreas:casereportandreviewoftheliteratureValentinaBeltrame1,MarioGruppo1,DavidePastorelli2,SaraPizzi3,StefanoMerigliano1andCosimoSperti1*AbstractPrimaryextra-gastrointestinalstromaltumor(EGISTs)arisinginthepancreasisextremelyrare:only20caseshavepreviouslybeenreportedintheEnglishliteraturefrom2000to2013.
WereportedacaseofEGISTofthepancreasina69-year-oldwomanwhopresentedwithabdominalpainandwithasolid,heterogeneouslyenhancingneoplasmintheuncinateprocessofthepancreas,revealedpreoperativelybyanabdominalcomputedtomographyscan.
Adiagnosisofneuroendocrinetumorwassuggested.
Positronemissiontomographywith68Ga-DOTATOCdidnotshowpathologicalaccumulationofthetracerinthepancreas.
Thepatientunderwentenucleation,underultrasonicguidance,ofthepancreatictumorthatemergedtothesurfaceofthepancreas.
HistopathologyandimmunohistochemicalexaminationconfirmedthefinaldiagnosisofEGISTofthepancreas(CD117+),withonemitosisper50high-powerfields.
Althoughrarely,GISTcaninvolvethepancreasasaprimarysite,andthistumorshouldbeconsideredinthedifferentialdiagnosisofpancreaticneoplasms.
Keywords:Differentialdiagnosis,Gastrointestinalstromaltumor,Pancreas,Pancreatectomy,PancreaticneoplasmsBackgroundGastrointestinalstromaltumors(GIST)arethemostcom-monmesenchymaltumorsofthegastrointestinaltract,withanannualincidenceof10to20permillion[1].
GISTsareneoplasmsarisingfrom,ordifferentiatingalong,alinesimilartothegastrointestinalpacemakercells,theintersti-tialcellsofCajal(ICCs)[2-4].
ICCsformanetworkaroundthemyentericplexusandwithinthemuscolarispropriaeofthegastrointestinalwall.
GISTsmayoccurintheentirelengthofgastrointestinaltractfromtheesophagustotheanus;however,themostcommonsitesarestomach(60%),smallintestine(30%),rectum(5%),andesophagus(computedtomography(CT)oftheabdomen(Figure1)revealedasolid,hypervascularnoduleintheuncinateprocessofthepancreas,measuring22*15mm.
Thepossibilityofaneuroendocrinetumorwasconsidered;thereforesheunderwentGallium-68somatostatinrecep-torpositronemissiontomography(PET)(68Ga-DOTA-TOC),withoutevidenceofneoplasmswithpathologicexpressionofsomatostatinreceptors.
Routinelaboratoryinvestigations,exocrineandendocrineserummarkers,andhormonalpanelwerewithinnormallimits,exceptforCEA:5.
7ug/L(referencevalueCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycredited.
TheCreativeCommonsPublicDomainDedicationwaiver(http://creativecommons.
org/publicdomain/zero/1.
0/)appliestothedatamadeavailableinthisarticle,unlessotherwisestated.
Beltrameetal.
WorldJournalofSurgicalOncology2014,12:105http://www.
wjso.
com/content/12/1/105intheheadofthepancreas;fine-needleaspirationofthelesionwasnotavailableatthatmoment.
Atlaparot-omy,inApril2013,awell-demarcated,rednodulewasidentifiedintheuncinateprocessofthepancreas;noat-tachwiththeduodenalwallwasfound.
Intraoperativesonographyshowedthatthe2-cmhypoechoicmasswasseparatedfromthemainpancreaticduct.
Carefulenu-cleationofthetumorwithHarmonicscalpel,underultrasoundguidance,wassuccessfullyperformed.
Pan-creaticcapsulawasclosedwithinterrupted,absorbablestitches.
Thepostoperativecoursewasuneventful,andthepatientwasdischarged7daysaftersurgery.
Macro-scopicexaminationshoweda2.
4cmwelldefined,ovoidmass.
Microscopically,thetumorwascomposedofspindlecells,withfocalatypia(Figure2).
Themitoticcountwasonemitoses/50highpowerfields(HPFs).
Immunohisto-chemicalexaminationshowedneoplasticcellsdiffuselypositiveforantibodiesagainstCD117(Figure3),focallypositiveforCD34(Figure4)andsmoothmuscleactin,whilecellswerenegativefordesmin.
Adiagnosisofpan-creaticGISTwithlowriskofmalignancyhasbeenplaced,pT2N0M0,stageIaccordingtoTNM(AJCC)classifica-tion[32].
Onmoleculargeneticexamination,deletionofthreenucleotidesinexon11ofc-Kitwasfound.
Shedidnotreceiveanyadjuvanttherapyaftersurgery;12monthslatersheisingoodgeneralconditionandthereisnoevi-denceofrecurrentdisease.
DiscussionWereportedararecaseofaprimarypancreaticGIST:thesmallsize,thewellcircumscribedmarginsofthele-sion,andthecontrastenhancementatCTexaminationsuggestedadiagnosisofneuroendocrinetumorofthepancreas.
GISTsreportedoutsidethegastrointestinaltractasapparentprimarytumorsaredefinedas'extra-gastro-intestinalstromaltumors'(EGISTs).
TheconceptofGISThasrecentlybeenestablished,duetotheprogressinimmu-nohistochemicalanalyses.
ItispresumedthatthesetumorsoriginatefromtheinterstitialcellsofCajal(ICCs),pace-makercells,whicharepresentthroughoutthewallofthegastrointestinaltractandwhichregulatethemotility.
ICCssharemanycharacteristicswithEGISTs,includingexpres-sionofCD117andCD34[2].
Infact,themostselectiveim-munohistochemicalmarkersdifferentiatingGISTsfromtruesmoothmuscletumorsistheexpressionofthec-Kitreceptortyrosinekinase(CD117antigen)in95%ofGISTs.
In2004,Yamamotoetal.
[31]reportedthatEGISTsshowsimilarKITmutationsoftypicalGISTssuggestingthatthesetumorshaveasimilarorigin.
However,atpresenttheoriginofEGISTsremainscontroversial.
SomeauthorsFigure1AbdominalCTscanshowinga2-cm,contrast-enhancedmass(arrow)intheuncinateprocessofthepancreas.
Figure2Stromaltumorcomposedofspindleandepithelioidcellswithfocalvacuolar(signetring)change.
(E&E,20*).
Figure3Immunostainforc-KIT:stronganddiffusecytoplasmicimmunoreactivity.
Beltrameetal.
WorldJournalofSurgicalOncology2014,12:105Page2of6http://www.
wjso.
com/content/12/1/105believethatGISTsandEGISTsarisefromthecommonpre-cursorcellofICCsandthesmoothmusclecellsofthegut,whichmayaccountfortheirgrowthwithinandoutsidethegastrointestinaltract[33].
Other,simpler,explanationsug-geststhatEGISTsareinfactmuralGISTswithextensiveextramuralgrowth,resultingineventuallossoftheircon-nectionwiththegutwall[33].
PancreaticGISTsareextremelyrare.
Wecollectedonly21cases(includingourpatient)fromtheEnglishliterature:theirclinicopathologicfeaturesandoutcomesaresumma-rizedinTable1.
Theageofthepatientsrangesfrom30to84years,withameanageof55.
0years.
Themale:femaleratiowas10:11.
Tenof21(48%)tumorsoccurredintheheadofthepancreas,fiveinthetail(34%),fourinvolvedbothbodyandtail(19%),andtwooccurredintheuncinateprocess(%).
EGISTrarely(n=1.
5%)involvedtheentirepancreas[24].
Thereisagreatvariationinsize(range,2.
4to34cm).
Themitoticcountwas10/50HPFsinfourcases(19%).
Molecu-larbiologyofEGISThasbeeninvestigatedinonlytwore-ports[14,22]andinourpatient:twoexhibiteddeletionofbasepairsinexon11,andoneshowedDNApolymorph-ismofL862Linexon18ofc-KITgene[22].
Allbutonepatientunderwentsurgery:onepatientwithmetastaticdiseasedied5daysafteradmissionwithoutoperation.
Onepatientunderwentpalliativeoperation(cystojejunost-omy)andtheremaining17patientsunderwentpancreaticFigure4ImmunostainforCD34:focalimmunoreactivity.
Table1Clinicopathologicfeatures,treatment,andoutcomeofEGISTsreportedintheEnglishliteratureAuthorYearAge(years)SexSite/TreatmentSize(cm)Mitoticcount(/50HPF)Follow-up,monthsNetoetal.
[11]200467FBodyandtail/DP+Imatinib20120;CD117(+)CD34(+)A,Relapse,1Yamauraetal.
[12]200454FTail/DP14Few;CD117()CD34(+)A,NED,30Krskaetal.
[13]200538FBodyandtail/DP171;CD117()CD34(+)A,NED,30Daumetal.
[14]200570FHead/PD+Imatinib102;CD117(+)CD34()A,NED,6Showalteretal.
[15]200872FTail/DP73;CD117(+)CD34()A,NED,27Yanetal.
[16]200847MUncinateprocess/NR2.
43;CD117(+)CD34()NAYangetal.
[17]200855MBodyandTail/DP+ImatinibNRNR;CD117(+)CD34(+)Relapse,24,-A,NED,41Harindhanavudhietal.
[18]200863FBody/Cystojejunostomy+Imatinib1610;CD117(+);CD34()A,NED,60Padhietal.
[21]201042FBodyandtail/DP356-8;CD117(+)CD34(+)A,NED,10Saifetal.
[22]201031MHead/PD+Imatinib848;CD117(+)CD34()A,Relapse,9Crisanetal.
[23]201061MTail34NRA,NED,3JoshiandRustagi[24]201084MWholepancreas/NOP34NR;CD117(+)CD34(+)Deadday5ofadmissionRaoetal.
[25]201140MHeadandbody/PD+Imatinib6.
58-10;CD117(+)CD34(+)Relapse,24;A,NED30Ceckaetal.
[26]201174FTail/DP11www.
wjso.
com/content/12/1/105resection(in5extendedtoadjacentorgans),onehadlocalresection,andone(ourcase)enucleationofthetumor.
Follow-upwasavailablein19cases.
Diseaserecurrencefollowingsurgerywasreportedinfivecases:threepatientsunderwentre-resectionandarealiveandfreeafter30,41,and48months,respectively.
Overall,18patientsarealivewithamediansurvivaltimeof17.
5months(range,1to66months).
Despitethelimitednumberofcasesandtheshortfollow-uptime,itappearsthatresectionofpancre-aticGISTSmayofferagoodprognosis,eveninrecurrentdisease.
TheclinicalpresentationofEGISTsisvariable,depend-ingonthelocationandsizeofthetumors.
Thetumormayevenbefoundincidentally.
Themostfrequentclinicalsymptomsare:abdominalpain,ileus,bleeding,anemia,andweightloss.
Ourpatientpresentedwithasmall,solid,hyperintenselesionresemblinganeuroendocrinetumor.
Asimilarfindingofsmall,solidtumorintheuncinateprocessofthepancreaswasreportedbyYanetal.
[16]inacaseofGISTdiagnosedbyEUSfine-needleaspiration(FNA):unfortunately,biopsywasnotavailableforourpa-tient.
Interestingly,50%(11/21)ofthereportedcasesshowedradiologicfeaturesofheterogeneouslymass(nec-roticareas)orsolid-cysticappearance;thus,problemsindifferentialdiagnosiswithcysticneoplasmsofthepan-creascouldbearise.
TheaccuracyofCTdeterminationofthepathologicaldiagnosisofapancreaticcysticlesionislessthan50%[34,35],butendoscopicultrasound-guidedFNAmaybehelpfulforthediagnosisofpancreaticlesions[36].
ThediagnosisofGISTisbasedonhistological,im-munohistochemical,andmolecularfeatures.
Microscopic-ally,thistumor,consistedofspindlecellandepithelioidcells.
Thecytologicdifferentialdiagnosisforthesespindlecellproliferationsincludesleiomyoma,schwannoma,fibro-matosis,inflammatoryfibroidpolyps,andgastrointestinalmuscularissampling[16].
ImmunoistochemicalpositivityofCD117confirmsthediagnosisofGIST.
GISTsexhibitabroadspectrumofclinicalbehaviors,withsomelow-risklesionsremainingstableforyears,whileotherspro-gressrapidlytometastaticdisease.
VariousparametersareproposedtopredictthemalignantpotentialofGIST,suchastumorsize,mitoticactivity,tumorlocation,non-radicalresection,tumorrupture,peritonealdissemination,metastasis,andinvasionintoadjacentorgans.
NationalIn-stituteofHealth(NIH)consensuscriteria(Fletcher'scri-teria)[37]proposedriskstratificationoftumorbehaviorintoriskcategoriesofverylow,low,intermediate,andhighriskofmetastasis,basedonitssizeandmitoticactivity.
Tu-morslargerthan10cminsizeandwithmorethan10mi-tosesper50HPFareathighriskofaggressivebehavior[33,37].
StandardtreatmentforprimaryGISTiscompletesurgicalresectionwiththeaimtoobtainnegativemicro-scopicmarginsofresection[13,38,39].
LymphaticspreadofGISTsisuncommon;therefore,asystematiclymphnodedissectionisnotastandardsurgicalmanagement.
Inourpatientweperformedasimpletumor'senucleationbecauseofapreoperativediagnosisofneuroendocrinetumor.
How-ever,afterdiscussionwithoncologists,thesmallsizeofthelesionandthelow-riskaccordingtopreviouslyreportedprognosticcriteria[37],suggestedthatitwasanadequateoperation,asreportedinarecentstudy[40].
Thepatientisaliveandfreeofdisease1yearafteroperation.
Thesurgicalmanagementmayofferprimarysurgeryatthetimeofdiag-nosis,neoadjuvantchemotherapyfollowedbysurgery,adju-vanttherapyaftersurgery,ordebulkingsurgeryinpatientswithmetastaticoradvanceddisease.
ObservationonlywasrecommendedincasewithR0resectionorlow-riskGIST.
Inrecentdecades,medicaltherapyforGISTisimproved(Imatinib,Sunitinib,Nilotinib,Sorafenib,Dovitinib,andsoon)andconsequentlydisease-freesurvivalaftersurgeryisalsomuchimproved:infact,itisrecommendedinpatientswithR1orR2resection[41].
Theresultsofsomeclinicaltrials[42-49]withtargetedtherapyofGISTarereportedinTable2.
Obviously,dataabouttargetedtherapyforEGISTTable2SelectedagentsinvestigatedinthemanagementofGISTAuthorYearPts(n)PhasestudyTreatmentEndpointOutcome(%ormedian)PvalueDemetrietal.
[42]2002147IIImatinibOR81.
6%DemetriGDetal.
[43]2006312IIISunitinib/placeboTTP27.
3vs.
5.
4weekswww.
wjso.
com/content/12/1/105arelimited.
Inthereviewoftheliterature,among19high-riskEGISTs,onlyninecases(47%)receivedadjuvantIma-tinibtherapy(Table1).
ConclusionInconclusion,wereportanewcaseofEGISTarisingfromthepancreas,misinterpretedasneuroendocrinetumor.
Despiteitsrarity,GISTshouldbekeptinmindinthedif-ferentialdiagnosisofprimarytumorsofthepancreas,es-peciallywhenahypervascularlesion,solidorcystic,islackingsomatostatinreceptorsatPETexamination.
Rad-icalresectionofpancreaticGISTsisthetreatmentofchoice,andrepeatsurgeryforrecurrencemayofferapro-longedsurvival.
ConsentWritteninformedconsentwasobtainedfromthepatientforpublicationofthiscasereportandanyaccompanyingimage.
Acopyofthewrittenconsentisavailableforre-viewbytheEditor-in-ChiefofthisJournal.
CompetinginterestsTheauthorsdeclarethattheyhavenocompetinginterests.
Authors'contributionsVBandCSconceivedthestudy,carriedouttheliteraturesearch,anddraftedthemanuscript;MGandDPhelpedinmanagementofthepatient;SPcarriedoutthepathologicdiagnosisandimmunoassays;SMmadecriticalrevisionsandsupervision.
Allauthorsreadandapprovedthefinalmanuscript.
AcknowledgmentWethankMsFlaviaTrabuioforherexcellenthelpinthepreparationofthemanuscript.
Authordetails1DepartmentofSurgery,OncologyandGastroenterology,3rdSurgicalClinic,UniversityofPadua,Giustiniani2,35128,Padua,Italy.
2DepartmentofOncology,RareTumorsUnit,VenetoInstituteofOncology,Padua,Italy.
3DepartmentofPathology,UniversityofPadua,Padua,Italy.
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