Postoperative complications after removal of pleomorphic adenoma from the parotid gland: A long-term follow up of 297 patients from 2002 to 2016 and a review of publications

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BritishJournalofOralandMaxillofacialSurgeryxxx(2019)xxx–xxx

ScienceDirect

Postoperative

complications

after

removal

of

pleomorphic

adenoma

from

the

parotid

gland:

A

long-term

follow

up

of

297 patients

from

2002

to

2016

and

a

review

of

publications

Paola

Bonavolontà

a

,

Giovanni

Dell’Aversana

Orabona

a

,

Fabio

Maglitto

b

,

Vincenzo

Abbate

a

,

Umberto

Committeri

b,∗

,

Giovanni

Salzano

b

,

Giovanni

Improta

c

,

Giorgio

Iaconetta

e

,

Luigi

Califano

d

a_Department_{Neurosciences,}_Reproductive_and_{Odontostomatological}_Sciences,_Federico_II_University_of_Naples,_Naples,_Italy b_Department_{Neurosciences,}_Reproductive_and_{Odontostomatological}_Sciences,_Federico_II_University_of_Naples,_Naples,_Italy c_Department_of_Public_Health,_Federico_II_University_of_Naples,_Naples,_Italy

d_Federico_II_University_of_Naples,_Naples,_Italy

e_Department_of_{Neurosurgery,}_University_of_Salerno,_Salerno,_Italy

Accepted13August2019

Abstract

Pleomorphicadenomasarerounded,lumpy,capsulatedlesionsthataremorecommoninwomen.Theyaretypicallybenign,butcanbe associatedwithmalignancyinaminorityofcases(suchascarcinomaexpleomorphicadenoma),between3%-12%ofthetime,accordingto availabledata.Thepurposeofourstudywastoevaluateclinicaloutcomesinpatientswithbenignparotidglandtumoursafterextracapsular dissection(ECD)orsuperficialparotidectomy(SP).Wemadearetrospectivestudyof297patientswhohadhadbenigntumoursoftheparotid gland,andhadbeenreferredtoourdepartmentfrom2002–2016tohaveeitherprocedure.Wemeasuredthestatisticaldifferencesbetweenthe twotechniques(evaluatedrecurrencerateandcomplications)withthechisquaredtest.Thechosenlevelofstatisticalsignificancewasp<0.05. Median(range)follow-uptimewas43months(25–168)months.HaematomaandhypoaesthesiaweresignificantlymorecommonafterSP thanafterECD(8.9%comparedwith7.7%,and16.8%comparedwith5.6%,respectively).Transientfacialnerveinjury,Freysyndrome,and facialparalysisweresignificantlymorecommonafterSPthanafterECD(23.6%comparedwith1.5%,6.7%comparedwith1%and6,7% comparedwith0%,respectively).ECDhadtheadvantageofreducedoperatingtime,lowermorbidityandlowerrecurrencerate,andcould beconsideredthetreatmentofchoiceforpleomorphicadenomaoftheparotidglandup(to3cm)whicharemobileandsitedinthesuperficial lobeoftheparotidgland.

Keywords:pleomorphicadenoma;extracapsulardissection;superficialparotidectomy

∗_{Corresponding}_author_at:_Via_Pansini_n.₅_Napoli_80100,_Italy.

Tel.:0817462175,Fax:0817462190

E-mailaddresses:p.bonav@gmail.com(P.Bonavolontà), umbertocommitteri@gmail.com(U.Committeri).

Introduction

Tumoursofthesalivaryglandsarenotcommon,and gener-allycomprise2%-4%ofneoplasmsintheheadandneck.1 Three-quartersofthemarebenign,andmostoriginateinthe parotid gland (70%). Amongthem, pleomorphicadenoma isbyfarthe mostcommonbenignepitheliallesion(81%), https://doi.org/10.1016/j.bjoms.2019.08.008

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50%-70%aresalivarytumours,andcystoadenolymphoma orWarthintumouraccountforabout25%.2

Pleomorphic adenomas, also known as “benign mixed tumours”, are rounded,lumpy, capsulated lesions that are more common in women, and most are found in adult-hood.Theyaretypicallybenign,butcanbeassociatedwith malignancyinaminority of cases(such as carcinoma ex-pleomorphic adenoma), between 3% - 12% of the time, accordingtoavailabledata.2

Surgicaltreatmentsfor benignparotid glandneoplasms began with enucleation in the late 1800s, but during the late1900s,technicalprocedureswerechangedtoremovethe masswithaportionofsurroundingnormalparotidgland tis-sue,toavoidrecurrence,butindoingsocreatedanincreasein complications.3 Parotidglandsurgeryremainschallenging, becausethereisnoconsensusontreatment,butthetwomost commontechniquesareextracapsulardissection(ECD),and superficialparotidectomy(SP).1,4Althoughthenumbersfor recurrenceafterthesetechniquesareacceptable,5dissection ofthefacialnerveanditsbranchesforremovalofpartsofthe glandcanleadtocomplicationspostoperativelythatarenot acceptableforthetreatmentofabenignlesion.Typical com-plicationsofparotidglandsurgeryinclude:defectivewound healing;woundinfections; dehiscence;hypertrophic scars; seromas;haematomas;sialocoeles;salivaryfistulas; anaes-thesiaandparaesthesiaaround dermalincisionsorthearea suppliedbythegreatauricularnerve;temporaryand perma-nentfacialparesis;Freysyndrome;andgustatorysweating.6 TheaimofourstudywastocomparetheresultsofECD andSP,toreducecomplicationsandrecurrence.Weanalysed ourdataintermsofthesuccessoftreatment,amountof com-plications,andrecurrence,onalargeseriesofpatients(297), withlong-termfollowup.

Methods

We carried out a retrospective study of all patients who hadhadbenigntumoursoftheparotidgland,andhadbeen referredtoourdepartmentfrom2002-2016.Wecollected generalinformation(age,sex,coexistingconditions),aswell asspecificclinicaldata.Bimanualpalpationoftheglandsand neckweredonetoobtainacharacterisationofthe localisa-tion,dimension, mobility, andtensionrelatedtothe effect of the mass. Clinical assessment of facial nerve function was made preoperatively according to House and Brack-manncriteria.6Ultrasoundscan(US),computedtomography (CT) or magnetic resonance imaging (MRI),or both, and fine-needlecytologywerecarriedoutinallpatients preoper-atively.

Exclusioncriteriawere:diagnosisof amalignantlesion orotherbenignlesiondifferentfrompleomorphicadenoma, eitherbeforeorafteroperation;anygradeoffacialnerve dys-functionpreoperatively;patientswhohadbeenlostatregular followupand;thosewhowerebeingtreatedforrelapse.

AccordingtothecategoriesdevelopedbyQueretal,7we usedECDforallcasesofasingle,mobile,lesionof3cmor lessindiameter(Quer’sCategoryI)thatwerelocated super-ficiallywithinthelaterallobeoftheparotidgland,thathad beendiagnosedasbenignpreoperatively.

Weused parotidectomy for tumourswithadiameter of 3cmorlessthatweresiteddeepintheparotidlobe(Quer’s CategoryII),orthosethatwerelargerthan3cmindiameter (Quer’sCategoryIII-IV).

Allpatientshadregularfollowup,andcomplicationswere documentedimmediatelypostoperatively,duringtheirstayin hospital,andateachsubsequentfollow-upvisit.

Thisstudywasapprovedasan“exemptstudy”bythe Insti-tutionalReviewBoardattheUniversityFedericoIIofNaples. Thisinvestigation observedthe DeclarationofHelsinkion medicalprotocolandethics.

Operativetechnique

Extracapsulardissection

WeconsideredECDtobetheselectiveresectionofatumour withsafemargins.Inparticular,thesurgeonmadeaskin inci-sionthatconvertedtoamodifiedBlairincision,whichisa modificationof the facelift technique.Itis donetoreduce the aesthetic impactof the surgical scar, and allows care-fuldissectionofthetumour,andrespectsandpreservesthe capsule,withnoidentificationofthefacialnerve.Inthis tech-niqueonlytheareaoftheglandthatinvolvesthetumouris removedwithamarginof1.5cm.

Superficialparotidectomy

SPistheremovalofthesuperficialparotidlobewithcomplete nervedissection.TheskinincisionstartswithamodifiedBlair techniquefromthepreauricularregionandextendsuptothe internalmarginofthetragus,reachestheearlobe,andthen goesonposteriorlyfor2-3cmonthemastoid.Thesuperficial muscularaponeuroticsystemisraised,andthegreater auric-ularnerveisidentifiedandpreserved.Thecommontrunkof thefacialnerve,afteritsidentification,isdissected,isolated, and controlled by means of faradic stimulation. After the removalofthetumour,haemostasisisconfirmed,thefascial planesarestitched,andtheskinisclosedwithnon-resorbable sutures.

Statisticalanalysis

Statistical calculations were done with the aid of SPSS (version 17.0).The statistical differences betweenthe two techniquesrelatingtoevaluatedrecurrencerateand compli-cationsweremeasuredwiththechisquaredtest.Probabilities oflessthan0.05wereacceptedassignificant.

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Fig. 1.Postoperative complications after extracapsular dissections and superficialparotidectomies.

Results

From2002to2016,thediagnosisofpleomorphicadenoma wasgivenin297/441patientswhohadhadbenignparotid tumoursurgery(67%).

Amongthese,14patientswereexcludedfromthisstudy becauseofirregularfollowuporbecausetheyhadevidence offacialnervepalsyevenbeforeoperation.Forthisreason, we enrolled283 patients (154 femaleand129 male)aged between26and79,mean(SD)age52(10.6)years.

Ofthese,wedidextracapsulardissectionin194patients, andsuperficialparotidectomyin89.Median(rangefollow-up timewas43(25–168)months.Postoperativecomplications aresummarisedinFig.1.

Achisquaredtestwasalsocalculatedbetweentwogroups (complicationsYES/complicationsNO)andtheoperations. Apvalueof<0.00001wasfoundwiththistest,whichwas sig-nificant(n=283;X2(9)=104.39,p<0.001;likelihoodratio (X2(9))=108.11,p<0.001).

Transient facial nerve injury, hypoaesthesia, Frey syn-drome,andfacialparalysisweresignificantlymorecommon aftersuperficialparotidectomythanafterextracapsular dis-section(23.6%comparedwith1.5%,16.8%comparedwith 5.6%, 6.7% compared with 1% and6,7% compared with 0%,respectively)(Observationfrequencies,Fig.2A-Dand Table1).

Discussion

Pleomorphic adenoma is a slow growing, usually demar-cated, and mobile tumour that occurs more commonly in olderwomen.Itconstitutesabout40%-60%ofbenign sali-varyglandtumourssitedinthesuperficialparotidglandlobe inabout80%ofpatients.2

The most relevant structural components of this kind of lesion are the capsule, parenchyma, andstroma. Many authors have described parenchyma-rich and stroma-rich

Table1

Comparisonofextracapsulardissectionsandsuperficialparotidectomy.Data arenumber(%). Complication Extracapsular dissection (n=194) Superficial parotidectomy (n=89) pvalue Haematoma 15(7.7) 8(8.9) 0.719 Seroma 3(1.5) 5(5.6) 0.055 Fistula 2(1) 4(4.49) 0.060 Hypoaesthesia 11(5.6) 15(16.8) 0.002 Prominentscar 4(2) 3(3.3) 0.510 Freysyndrome 2(1) 6(6.7) 0.007

Transientfacialinjury 3(1.5) 21(23.6) <0.001

Facialparalysis 0 6(6.7) <0.001

Recurrence 8(4.1) 4(4.49) 0.886

subtypes.Thecapsuleisusually0.015-1.75mmthick,andis thickerinparenchyma-richtumoursthanstroma-richones.2 The close association betweenthe gland and the facial nerve, and the considerable prospect of recurrence, has shapedsurgicaltechniquesforparotidglandneoplasmsover theyears.8

Parotid surgery for pleomorphic adenoma has been developed considerably in the past century, passing from enucleation of the tumour to parotidectomy, which was associatedwithmorecomplications.9,10Surgicalexperience and familiarity with the complex anatomy of the facial nerveandotheradjacentvascularandneural structuresare strictlyrequiredtoavoidcomplications,particularlywhenthe anatomy couldhavebeenalteredbyinflammation, lesions, previous operations or radiation treatments, or both. The choiceofthemostappropriatetreatmentintheexcisionof theparotidglandisessential,asisintraoperative identifica-tionandpreservationofthepseudocapsulethatsurroundsthe lesion.11

Generally, the choice of treatment isintended toavoid postoperative complications. Major advances in surgical techniqueshaveshiftedthefocusfromrecurrenceandfacial nervedamagetothemanagementofotheroutcomes,suchas damagetothegreatauricularnerveandFreysyndrome.12

ECD is a technique that involves a total excision of a benignparotidtumourthatissurroundedbyhealthy glandu-lartissue,withsafemarginsandcompletenervedissection. PreviouspublicationshaveshownthatlimitedECDdoesnot resultinanincreasedincidenceofrecurrence.13

In1993,Dalleraetalshowedtheirresultsafter71patients withpleomorphicadenomawhohadECDwitharecurrence rate of 5.4%.14 In 1996, McGurk et al found no differ-enceinrecurrencebetweenpatientswhohadECDandthat recorded inthose whohadSP.15 In their meta-analysisof 2014,Forestaetalemphasisedthatinpatientswithunilateral pleomorphicadenoma(ofless3cmindiameter)ECDwasa viableapproachinconsiderationofsuccessfuloutcomesand safety.13In2015,Mantsopoulosetalproposedandfocused attentiononthepossibilityofaminimally-invasiveapproach forECD,becauseoftheconsiderablereductioninoperating time.16

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Fig.2.Comparisonbetweenobservationfrequenciesrelatedtothefollowingpostoperativecomplications:(A)Transientfacialnerveinjury;(B)Hypoaesthesia; (C)Facialparalysis;(D)Freysyndrome.

Albergottietal17 showedthatECDhasasimilar recur-rencerateasSPwithfewsurgicalcomplications.ECDwas doneinmostcasesofmobiletumoursthatweresitedinthe superficiallobeoftheparotid,andwithdiametersoflessthan 3cm,(2–2.5cm).18 McGurk15reportedareductionof inci-denceofFrey’ssyndromefrom32%incasestreatedbySP, to5%inECD.Shehataetal19 showedthatECDis associ-atedwithreducedoperativetime,lowmorbidity,andshorter hospitalstay,confirmingthatthiskindoftechniqueseemsto besafeintrainedhands.

TheaimofSPistoallowtheremovalofthebenignparotid masswithadequatemarginsofsafetyparotidtissuearound it.Itwasdone inmost casesthat comprisedlarger,firmer, and more deeply-sited lesions. As reported by Patey and Thackray,complicationssuchasFreysyndrome,haematoma, fistula, and injury tothe greater auricular nerve are more commonlyseenafterparotidectomythanafterextracapsular dissection.20

AspromptedbyKadletzetal.,1regardingpermanentfacial palsyandrecurrentdisease,SPstillremainsthetreatmentof choiceintermsofsuperiorclinicaloutcome,eventhoughit ismoretime-consumingthanECD.

From2013the useofendoscopic toolsinmaxillofacial surgeryhasbeenimprovedfortheapproachtolesionsofthe salivaryglands.

AsreportedbyAbbate etal21 in acadavericstudy,the endoscopicapproachcanbeanalternativetoassessthe acces-soryparotidgland.22 Itwould beadvisable toincreasethe

studyoftheendoscopicanatomyoftheparotidarea,toextend thesurgicalendoscopicindications.Chenshowedhisresults of the aesthetic outcomes in 11 young patients who had endoscopically-assisted ECD of benign pleomorphic ade-nomas of the parotid gland through apostauricular sulcus approach.Thistechniqueseemedtobesimpleandfeasible, anditachievedexcellentaestheticresults.23

Allthedifficultiesandlimitationsofaminimally-invasive operation may be considered, such as restrictedspace for manoeuvring that isassociated withalimited fieldof vis-ibility, the need for lengthytraining, and asteep learning curve.

In conclusion, our large study enabled us to compare theadvantagesandweaknessesofbothsurgicalapproaches. Basedonourdata,westillrecommendECDasaviable alter-nativetoSPintermsofsuccessfuloutcomefortumoursunder 3cm.Ithasconfirmedthepreliminaryresultsreportedinour previousstudyandthoseinarecentbibliography.23,24

Unfortunately,thereareonlyfewprospectivestudieson procedure-specificincidencesofcomplicationsafterbenign parotid surgery. Predictive factors for postoperative facial dysfunction remain controversial. Ruohoalho has recently published an interesting prospective study about the com-plication rates and assessed risk factors of postoperative transientfacialpalsy.Heshowedthatageandalongoperation increasetherisk.25

Nevertheless,weaimtokeepourmindsopentoall pos-sibleinnovationsthatwillallowanynewsurgicalapproach,

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notonlytoimprove effectiveness, butalso toincreasethe optionsforaminimally-invasiveapproach.

Ethicsstatement/confirmationofpatients’permission

Thisstudywasapprovedasan“exemptstudy”bythe Institu-tionalReviewBoardattheUniversityFedericoIIofNaples. Patients’permissionwasnotnecessary.

Conflictofinterest

Wehavenoconflictsofinterest.

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