Incidental appendiceal mucinous neoplasm mimicking a left adnexal mass: A case report

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InternationalJournalofSurgeryCaseReports74(2020)132–135

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International

Journal

of

Surgery

Case

Reports

jo u r n al ho me p a g e :w w w . c a s e r e p o r t s . c o m

Incidental

appendiceal

mucinous

neoplasm

mimicking

a

left

adnexal

mass:

A

case

report

Ammar

Aleter

_,

_Walid

_El

_Ansari

d_{SchoolofHealthandEducation,UniversityofSk¨ovde,Sk¨ovde,Sweden}

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received1July2020

Receivedinrevisedform30July2020 Accepted30July2020

Availableonline12August2020

Keywords:

Appendicealmucinousneoplasm Appendix

Mucocele

Mimickingovariantumor Misdiagnose

Casereport

Pelvicultrasonography

a

b

s

t

r

a

c

t

INTRODUCTION:Appendicealmucinousneoplasmisararetypeofappendicealtumorswhichcanpresent

inavarietyofsymptomsandisdifficulttodiagnose.Preoperativediagnosisdependsmainlyondiagnostic

imagingsuchasultrasonographyandcomputerizedtomography(CT)scan.Thisuncommoncasereport

discussesanappendicealmucinousneoplasmmimickingaleftadnexalmassonpresentation,physical

examinationanddiagnosticimagingfindings.

PRESENTATIONOFCASE:Thisisa61-year-oldfemalefoundtohavealargeleftadnexalmassduringfollow

upultrasonography.Thepatientrefusedfurtherimaging,andduringlaparotomy,shewasfoundtohave

anappendicularmucocelewithnormalleftandrightovaries.

DISCUSSION:Appendectomywasdoneandthefinalpathologycameasappendicealmucinousneoplasm.

Herpost-operativecourseand3yearsfollowupwereuneventful.

CONCLUSIONS:Theequivocalsignsandsymptomsalongwiththeanatomicalpositionofappendiceal

mucocelemakesitdifficulttodiagnoseandcanmimicothertypesoftumors.Therefore,itshouldbe

consideredinthedeferentialdiagnosisoflowerabdominalandpelvicmasses.

©2020TheAuthor(s).PublishedbyElsevierLtdonbehalfofIJSPublishingGroupLtd.Thisisanopen

accessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

Appendicealmucoceledescribestheprogressivedilatationof thevermiformappendixduetoabnormalmucusaccumulationin thelumen[1].Mucusisretainedasaresultoflumenobstruction orhyperproductiondue tobenign(fecaliths,postinflammatory fibrosis,hyperplasticpolyps,serratedadenomas)ormalignant(low orhigh-gradeappendicealmucinousneoplasm,carcinoidtumors, mucinousadenocarcinomas)pathologies[2].Appendiceal muco-celesformedduetoappendicealmucinousneoplasms(AMNs)are exceptionallyrare,withanincidenceof0.12casesper1million individualsperyear[3,4].

AMNsareoccasionallyfoundincidentally,duringfollowupor atthetimeofsurgeryforothercauses,andfrequentlydiagnosed inthelatestages[5].ThesymptomsofAMNvarysignificantly,and itisasymptomaticin25%ofcases[6].Hence,awiderangeof dif-ferentialdiagnosesshouldbeconsidered,toincludeappendicitis, mesentericorduplicationcyst,oradnexalmass[7].

∗ Correspondingauthorat:DepartmentofGeneralSurgery,HamadGeneral Hos-pital,Doha,Qatar.

E-mailaddress:welansari9@gmail.com(W.ElAnsari).

Inthecurrentcasereport,wepresentanincidentalappendiceal mucinousneoplasmmimickingaleftadnexalmass.Weusethe AmericanJointCommitteeonCancer(AJCC)8thedition[8]forthe classification,prognosisandtreatmentofAMNs,andthecaseis reportedinlinewiththeupdatedconsensus-basedsurgicalcase report(SCARE)guidelines[9].

2. Casepresentation

A61yearoldJordanianfemalewasreferredtotheobstetricsand gynecologyclinicatourinstitutionfromhealthcenterdueto sus-pectedlargeleftovarianmassdiscoveredbypelvicultrasound(US). Thepatientwaspostmenopausal(gravida7,para6,1abortion).Her lastchildbirthwas25yearsbackandpasthistoryrevealedthatshe underwenthysteroscopyandpolypectomyofanendometrialpolyp 3yearsago.Thenewlydiscoveredmasswasfoundduringher reg-ularfollowup.Uponthisincidentalfinding,thepatientwasnot complainingofanygynecologicalsymptoms.Shewasmenopausal since20years,withnocomplaintsofabdominalpainormass, vagi-nalbleedingordischarge,orweightorappetitelossduringthepast months.Therewerenoothergastrointestinalorurologic symp-toms,andtherestofhersystemicexaminationwasunremarkable. Herfamilyhistorywasnegativeforgynecologicalor gastroenterol-ogycancers,but thepatienthad comorbiditiesincludingtype2

https://doi.org/10.1016/j.ijscr.2020.07.081

2210-2612/©2020TheAuthor(s).PublishedbyElsevierLtdonbehalfofIJSPublishingGroupLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://

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A.Aleter,W.ElAnsari/InternationalJournalofSurgeryCaseReports74(2020)132–135 133

Fig.1. Pelvicultrasoundshowinglargeleftadnexalmass:rightovarycouldnotbe seenattimeofscanduetooverlyingbowelgas.

Fig.2.Pelvicultrasoundshowinglargeleftadnexalmass(10.0×4.2cm)with cal-cifications.

diabetesmellitus,hypertensionandhyperlipidemiawhichwere controlledbyoralmedications.

Examinationofthepatientrevealedthatshewasvitally sta-blewithunremarkableabdominalorgynecologicalfindings,and nomasscouldbepalpatedinthelowerabdomen.Investigations showedthatherlaboratorytestswereunremarkableexceptfor irondeficiencyanemiaand mildlyelevatedcancerantigen19-9 (CA19-9)(40U/mL).Othertumormarkersforovarianandother solidintraperitonealorganswerewithinthenormalrange:cancer antigen125(CA125),cancerantigen15-3(CA15-3)and alpha-fetoprotein(AFP)were9U/mL,13U/mLand2Ng/mLrespectively. HerpelvicUS(Figs.1and2)showedlargeleftadnexalovalshaped heterogeneoussolidmasslesion(10.4×4cm),containingareasof calcification,andtheleftovarycouldnotbeseen.Boththeright ovary(2.9×2cm)andtheuteruswereunremarkable.Nofreefluid wasfoundinthepelvis.ThepatientwasreferredforMRIabdomen andpelvis,butsherefusedtoproceedwithanyfurtherimaging. Theconditionwasdiscussedthoroughlywiththepatientanddue toahighsuspicionofovarianmalignancy,thedecisionwasmade toproceedwithsurgery.Wedidnotstartwithlaparoscopydue tolargetumorsize(10.4×4cm),asexploringthepelvicregion, resectingthetumoranddeliveringitwouldhavebeenvery dif-ficultandcouldexposethepatienttofurthercomplications.The patientwaspostedforexploratorylaparotomywithorwithout totalabdominalhysterectomywithsalpingo-oophorectomy.

Duringlowermidlinelaparotomybyanexperiencedsurgeon andafterfullinspectionofthepelvicorgansincludingrightandleft adnexaalongwiththeuterusandsigmoidcolon,thepatientwas unexpectedlyfoundtohavealargeappendicealmassatthe ter-minalportionofherappendixapproximately15cm(long)×5cm (wide).Theappendixwasintactwithnospillageorperforation, andnoperitonealnoduleswerefound(Fig.3).Theuterusandboth ovarieswerenormal.Appendectomywithexcisionalbiopsyofthe

Fig.3.Appendicularmucocelepostresection:appendixwasremovedintact with-outspillage.Arrowpointstosurgicalknotneartheproximalresectionmarginwhich wasfoundtobefreeofmalignancy.

Fig.4. Villousandflatproliferationofmucinousepithelialcellsliningthe appen-dicealmucosainLAMN,HX&E,x4.

Fig.5.Flatproliferationofmucinousepithelialcellswithlowgradenuclearatypia inLAMN,HX&E,x20.

omentumthatwasattachedtotheappendixwashenceperformed. Thepost-operativeperiodwasunremarkable,withnocomplaints orcomplications,thepatientwasstablevitallyandstarteddieton day1.Shewasfollowedforthenext2daysthendischarged.

Herhistopathologyresultsindicatedadiagnosisoflowgrade appendicealmucinousneoplasm(LAMN,17_×3cm).Figs.4–6show villousandflatproliferationofmucinousepithelialcellsliningthe appendicealmucosawithlowgradenuclearatypia.Theacellular

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Fig.6. AcellularmucindissectthemuscularispropriaoftheappendixinLAMN, HX&E,x10.

mucinouscellshadinvadedintothemuscularispropria,the proxi-malandmesentericmarginswereuninvolvedbytumor,andthere werenoidentifiabletumordeposits,lymphovascularorperineural invasion.Nolymphnodeswherefoundinthesubmittedspecimen andthepathologicalclassificationwaspT2,pNx[10].Staging com-puterizedtomography(CT)scanofthechestandabdomeninorder todetectanydistantmetastasiswerenegative.Thepatientwas referredand discussedatourgastro-intestinalmultidisciplinary (MDT)meeting,andtheplanwastofollowherupintheGeneral surgeryoutpatientclinicwithnoneedforfurtherinterventionor completionsurgery.Thepatientwasfollowedforthenext3years withnosignsofrecurrence.Shewassatisfiedwiththeoutcome. 3. Discussion

AMNis a very raredisease withheterogeneousclinical fea-tures[11]. Tothebestofourknowledge,thecurrentcasecould bethesecondcasereporteddescribinganAMNmimickingaleft ovarian tumor,the first beingfrom United States [12], despite thatmanycasereportsdescribedAMNmimickingarightovarian tumor[13,14]. Accurate preoperative diagnosis of AMNis usu-allydifficultdue to itsdiverseclinical features, lackof specific tumorbiomarkers, and susceptibilityof appendiceal neoplasms toinvolve/ metastasizetotheovarieshencemimicking ovarian tumors[11,15].

Intermsofdemographics,thecurrentpatientwasafemaleaged 61years, inagreementwithotherreports suggestingthat AMN tendstohaveaslightfemaleprevalenceandistypicallyfoundin patientsintheir5thand6thdecades;although,itmayoccuratany age[6,16].

As for presentation, the possible symptoms of appendiceal mucocelerangefromlowerabdominalorpelvicpain,fever, nau-sea,andvomitingtoasymptomaticpresentation[16,17].Ourcase representsaclassicexampleofthelackofsymptomsanddifficulty indiagnosisasthepatientwasactuallyasymptomaticandthemass wasfoundincidentallyduringroutineUSfollowup.

Intermsofimaging,diagnosisofappendicealmucoceleoften dependsondiagnosticimaging, anda main featurethat distin-guishesappendicealmucocelefromuncomplicatedappendicitisby USisthelackofappendicealwallthickeningof>6mm[18,19].We wereunabletoconfirmthepresenceorabsenceofappendiceal wallthickeningastheappendixcouldnotbeseparatelyidentified inrightiliacfossaduetoobscuringbowelgasandlargepelvicmass. SeveralUSappearancesspecificforappendicealmucocelemight beencounterede.g.abottle-likeshapedsolidappendicularmass slidingovertheuterusandovaries[19,20]orthehighlyspecific “onionskinsign”(concentricechogeniclayerswithseptaandfine

echoes)[21,22]canhelptodistinguishappendicealmucocelefrom anovariancyst.Unfortunately,suchdiagnosticappearanceswere notevidentintheUSweundertook.Otherssuggestedthatthe pres-enceoftheonionskinsignwithinacysticmassintherightlower abdominalquadrant,withanormalrightovary,couldbespecific forthediagnosisofappendicealmucocele[22].

Colonoscopy,MRI,andcomputedtomography(CT)areall valu-ableinvestigationsthatcanaidinreachinganaccuratediagnosis [23].Colonoscopicfindingse.g.“volcanosign”(appendicealorifice seeninthecenterofa firmmoundcoveredbynormal mucosa) and a bulbous submucosal lesion of the cecum, establish pre-cisediagnosisand areusefulfor themanagement [24].In MRI, appendicealmucocelelesionsarewellencapsulatedcysticmasses, hyperintenseonT2-weightedsequences,andhypo-orisointense onT1-weightedsequences[25].ThetypicalCTappearanceofan appendicealmucoceleisalargeandwell-encapsulatedcysticmass intheexpectedregionoftheappendix;calcificationsofthecyst wallareveryspecifictoappendicealmucoceleandarevaluable tocharacterizethemucocelefromanabscesscollection[25,26]. AlthoughCTisconsideredthemostinformativeimagingtechnique, thediagnosisismoredifficultintheabsenceofcysticcalcifications andfailuretoidentifytheorganoforigin[27].Unfortunately,the currentpatientrefusedtoprovideconsenttoproceedwithany fur-therimaging (eitherCT abdomenorMRIabdomen)asasecond modalityofdiagnosis.

Althoughalltheimaging techniquesand related signs high-lightedabovecanhelptodifferentiateanappendicealmucocele fromprimaryovariantumors,aprimaryAMNisrarelydiagnosed beforeoperationand histopathologicalexaminationwhen com-paredwithothermorefrequenttypesofappendicealorcolonic tumors[15].Hence,recentviewsadvocateconsideringAMNinthe differentialdiagnosisofanypelvicmassinelderlyfemalepatients, andnottorelymainlyonpreoperativeimagingtools[13–15].

Inourcase, thepre-operativemisdiagnosiswaspossiblydue to:a)thespecific‘onionskin’signwasnotevidentonUS;and,b) althoughcalcificationswithinthemassandthewallwerepresent, therightovarywasnotrecognizedduetoobscuringbowelgas,and themasswasmimickingaleftadnexalmass(Fig.2).Findingofa largeleftadnexalmassoccupyingthepelvicregionusuallyprompts additionaldiagnosticimagingtofurtheroutlinetheanatomybefore intervention,butthepatientrefusedfurtherMRIimaging.Others havereportedamisdiagnosedovarianmassduringpreoperative evaluationwhichturnedouttobeappendicealmucoceleduring surgicalexploration,andattributesuchmisdiagnosistothe mim-ickingsymptoms, nearbysurgicalanatomy and invasion ofthe neoplasmtothesurroundingovariesanduterus[13].

Asfortheprocedure,upondirectvisualizationofthelesionat thetimeofsurgery,thesurgeonrecognizedthispathologicalentity andperformedasimpleappendicectomythatwasneeded,andthe patientwasreferred forlongtermfollow-upafterdiscussionat ourgastrointestinalMDTmeeting.Thepatientwasrecentlyseen attheclinicafter3yearsoffollowupand wasrecurrence-free, usingtumormarkers(noelevation),colonoscopy,andimaging.

4. Conclusions

Thesymptomsofappendicealmucocelevarysignificantlyand arerelativelysimilartoovariantumors.Thesesimilarsignsand symptoms,alongwiththeanatomicalpositionoftheappendiceal mucocele,rendersitdifficulttodiagnoseappendicealmucoceleas itcanmimicothertypesoftumors,particularlyovariantumors. Althoughmultiplediagnosticimagingtechniquescanaidin reach-inganaccuratediagnosis,aprimaryAMNisrarelydiagnosedbefore operationandhistopathologicalexamination.Hence,high

suspi-CASE

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A.Aleter,W.ElAnsari/InternationalJournalofSurgeryCaseReports74(2020)132–135 135 cionisrequired,andrecentviewsadvocateconsideringAMNinthe

differentialdiagnosisforanypelvicmassinelderlyfemalepatients.

DeclarationofCompetingInterest

Theauthorsreportnodeclarationsofinterest.

Sourcesoffunding

Nothingtodeclare.

Ethicalapproval

ApprovedbytheMedicalResearchCenter(IRB),HamadMedical Corporation,referencenumber(MRC-04-20-133).

Consent

Writteninformedconsentwasobtainedfromthepatientfor publicationofthiscasereportandaccompanyingimages.Acopy ofthewrittenconsentisavailableforreviewbytheEditor-in-Chief ofthisjournalonrequest.

Author’scontribution

AmmarAleter:datacollection,interpretation,writingthepaper, editingthepaper.WalidElAnsari:studyconcept,data interpreta-tion,writingthepaper,editingthepaper.Allauthorsreviewedand agreedonthefinalversionofthepaper.

Registrationofresearchstudies

NotfirstinMan.

Guarantor

WalidElAnsari:welansari9@gmail.com. Provenanceandpeerreview

Notcommissioned,externallypeer-reviewed. References

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