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Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland

Chan-Woo Kim, Seong-Gon Kim

Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea

Abstract (J Korean Assoc Oral Maxillofac Surg 2012;38:314-7)

Basal cell adenoma (BCA) of the parotid gland is a rare benign tumor. In the parotid gland, BCA is occasionally difficult distinguish from adenoid cystic carcinoma in terms of clinical and pathological perspectives. An adenoid cystic carcinoma of the parotid gland grows slowly but spreads persistently to the surrounding tissues, particularly along the perineural spaces. In the present case, BCA of the parotid gland was misdiagnosed as an adenoid cystic carcinoma. We discuss the reason for such a misdiagnosis, and present a method for making a correct diagnosis.

Key words: Adenoma, Parotid gland[paper submitted 2012. 1. 30 / revised 2012. 4. 2 / accepted 2012. 5. 3]

evenwhenradicalexcisionhasbeenperformed7.

Clinicallyandhistopathologically,therearesimilarfeatures

betweenBCAandACC.Thetreatmentplaniscompletely

changedbytheresultofdiagnosis,especiallywhenmalignant

orbenign;hence theneedfordifferentdiagnoses. In this

paper,wereportBCAmisdiagnosedasACCintheparotid

gland,reviewliterature,anddiscussthedifferentdiagnoses

ofsimilarcases.

II. Case Report

InDecember2010,a50-year-oldmanwas referred to

ourhospital forevaluationofapalpablemass in the left

parotid region.He complained of severe burning and

pullingsensationintheleftpre-auriculararea.Thepainful

sensationbeganabout2yearsago,continuingintermittently

butnotworsening.Thephysicalexamination revealeda

massmeasuringabout5×4cm,whichwashard,tender,and

movable.(Fig.1)Therewasnosymptomonfacialnerve

function andcervical lymphadenopathy.Themagnetic

resonanceimageshowedawell-defined,non-homogeneously

enhancedmassonthedeepportionoftheleftparotidgland.

(Fig.2)TheT1W1imagerevealedmoderatetolowsignal

intensity(Fig.2.A),but theT2W1imageshowedhigher

signalintensityportioninthemiddleandmedialsiteofthe

lesionsuspectedtobeanecroticlesion.(Fig.2.B)Therewas

I. Introduction

Basalcelladenoma(BCA)of thesalivaryglands isa

rarebenignneoplasmhavingamonomorphoushistological

appearancedominatedbybasaloidcells1.The reported

datastate theincidenceofBCAinallsalivaryneoplasms

tobe1-3%2,3. It appearsmost frequently in theparotid

glandinadults1,4.Clinically,itisgenerallyaslow-growing,

asymptomatic,freelymovablemass1,4.

Asoneofthemostcommonandbestrecognizedmalignant

salivary tumors5, adenoidcystic carcinoma (ACC)was

firstreportedin1853byRobin,Lorain,andLaboulbene6.

ACCwas originally called cylindromabecause of its

histopathologicalmorphology.ACCwas recorded tobe

located in themajorandminor salivaryglands;usually

smallwith an incomplete capsule, it has a propensity

towardperineural spread5. Ithashigh,almost inevitable

predispositiontorecurinapersonwitholdage,occurring

Seong-Gon KimDepartment of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, 120, GangneungDaehag-ro, Gangneung 210-702, KoreaTEL: +82-33-640-2468 FAX: +82-33-640-3113E-mail: epker@chollian.net

ThisstudywassupportedbyagrantfromtheNext-GenerationBioGreen21Program(CenterforNutraceutical&PharmaceuticalMaterialsno.PJ009051),RuralDevelopmentAdministration,RepublicofKorea.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

CC

CASE REPORThttp://dx.doi.org/10.5125/jkaoms.2012.38.5.314

pISSN 2234-7550·eISSN 2234-5930

Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland

315

noevidenceofinfiltratingmargin.

Partialparotidectomywasperformed.Weapproachedthe

massbypre-auricular incision.(Fig.3.A)Thesuperficial

parotidlayeroftheparotidglandwasremoved,andthemass

wasexcised.(Fig.3.B)Thefacialnervetrunkwasconserved.

(Fig.3.C)

Macroscopically,anencapsulatedwhitishlesionmeasuring

4×4×2cmwasobserved.Themicroscopicexamination

showed infiltrating epithelial strandswithmultiple

cysticchangesandsolidpattern.The tumorcells rarely

showedkeratinizationandconsistedalmostexclusively

of intermediatecell type.Thetumorcellsweresmalland

cuboidal, exhibitingdeeplybasophilicnuclei and little

cytoplasm;mitoticactivitywasrarelyseen.Therewasno

perineuralinvasion(Fig.4),however.Immunohistochemical

examinationwas done aswell. The inmmunostain of

Fig. 1. Left preauricular area swelling and painless movable mass. Chan-Woo Kim et al: Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 2. A. In T1W1 magnetic resonance imaging, there is a well-defined and non-homogeneously enhanced mass on the deep portion of left parotid gland. B. There is higher signal intensity portion in middle and medial site of lesion. Chan-Woo Kim et al: Basal cell adenoma misdiag-nosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 3. A. Pre-auricular incision was done. B. Superficial parotid gland was removed and the mass was excised. C. Facial nerve trunk was conserved.Chan-Woo Kim et al: Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012

J Korean Assoc Oral Maxillofac Surg 2012;38:314-7

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wasnegative.(Fig.5)Initially,thepathologistconsideredthe

lesiontobeACC.

Nonetheless,wehaddoubtsonthepathologicaldiagnosis

because itwasnot inaccordwith thepatient’s clinical

symptomsandradiologicalfeature.Thus,werequestedare-

examinationonthesectiontoanotherclinicalpathologist.

ThefinaldiagnosiswasBCA,notACC.Thecellsof the

islandswerepalisadedandcuboidal in shape,with the

trabecularsubtypedemonstratingnarrow,cordlikeepithelial

strands.Therewasnoevidenceofmalignancy.

Therewasslightfacialweaknessinonethirdofthelower

leftpartoftheface.Thesymptompersistedfor6monthsbut

easedgradually.Thepatientwasmonitoredfor1year,and

therewasnoevidenceofthetumororsignsandsymptoms

recurring.

Discussion

BCAin the salivarygland isa rarebenignneoplasm,

consistingofisomorphicbasaloidtumorcells4,8.Constituting

only1%ofallsalivaryneoplasms2,9, it iscontroversialfor

itsgenderpredominance8.Thetumorcangrowatanyage

butismostcommonamongold-ageadults8.BCAoccursin

epithelialcells,usuallyintheterminalduct8.Histologically,

ithasmanyvariantssuchassolid, tubular, trabecular,and

proliferatingcellnuclearantigenwasfrequentlypositive

in tumorcells,but thatofp53washardlyvisible.The

immunostain of cytokeratin-7was frequently positive

inglandular structure,but the samecannotbe said for

cytokeratin-14.Theimmunestainofsnailwasfrequently

positiveintumorcells,butthatofbeta-cateninwashardly

visible.Pan-KandS-100werepositivelystained,butwnt-1

Fig. 5. PCNA was frequently positive in tumor cells, but the immunostain of p53 was rarely stained. Cytokeratin-7 was frequently positive in glandular structure, but the cytokeratin-14 was rarely stained. Snail was frequently positive in tumor cells, but the beta-catenine was rarely stained. Pan-K and S-100 was positively stained, but wnt-1 was negative (x100). (PCNA: proli ferating cell nuclear antigen, Pan-K: pancy to ke ratin)Chan-Woo Kim et al: Basal cell adenoma misdiag-nosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 4. The tumor cells rarely showed keratinization and almost consisted of intermediate cell type. There were small and cuboidal, exhibiting deeply basophilic nuclei and little cytoplasm and mitotic activity was rarely seen (H&E staining, x100).Chan-Woo Kim et al: Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012

Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland

317

painless,andfreelymovable.Thepatientdidnotcomplain

abouthis lesionuntil2yearsago.Hehadnofacialpalsy

andlymphadenopathy.Therefore,clinically,ithadabenign

character,sowebelievedittobeabenigntumor.Nonetheless,

thehistopathologicalresultwasACC,althoughwecouldnot

believetheresult.Werequestedfortheexaminationofthe

sampletoanotherpathologist,expectingadifferentresult.

Trueenough,itwasBCA;weacceptedtheresultbecauseof

manyclinicalsimilarevidences.

Itisdifficulttodiagnosebasalcelladenomaintheparotid

gland, since it isuncommon in theparotidglandand it

seemstobejustanothertumor.Thesurgeonmustconsider

thepatient’sclinicalsymptom,radiologicalsymptom,and

pathologicalsymptom.

References

1. Gonzalez-GarciaR,Nam-ChaSH,Munoz-GuerraMF,Gamallo-AmatC.Basalcelladenomaoftheparotidgland.Casereportandreviewoftheliterature.MedOralPatolOralCirBucal2006;11:E206-9.

2. JunqueraL,GallegoL,deVicenteJC,FresnoMF.Bilateralparotidbasalcelladenoma:anunusualcase reportand reviewof theliterature.JOralMaxillofacSurg2010;68:179-82.

3. KawataR,YoshimuraK,LeeK,ArakiM,TakenakaH,TsujiM.Basalcelladenomaoftheparotidgland:aclinicopathologicalstudyofninecases--basalcelladenomaversuspleomorphicadenomaandWarthin'stumor.EurArchOtorhinolaryngol2010;267:779-83.

4. EstevesAR,DibLL,deCarvalhoLV.Basalcelladenoma:acasereport.JOralMaxillofacSurg1997;55:1323-5.

5. BradleyPJ.Adenoidcysticcarcinomaof theheadandneck:areview.CurrOpinOtolaryngolHeadNeckSurg2004;12:127-32.

6. StellPM.Adenoidcysticcarcinoma.ClinOtolaryngolAlliedSci1986;11:267-91.

7. JonesAS,HamiltonJW,RowleyH,HusbandD,HelliwellTR.Adenoidcysticcarcinomaoftheheadandneck.ClinOtolaryngolAlliedSci1997;22:434-43.

8. NevilleBW.Oralandmaxillofacialpathology.1sted.Philadelphia:Saunders;1995.

9. EllisGL,AuclairPL,GneppDR.Surgicalpathologyofthesalivaryglands.Philadelphia:Saunders;1991.

10. NevilleBW,DammDD,AllenCM,BouquotJE.Oralandmaxillo-facialpathology.2nded.Philadelphia:WBSaunders;2002.

11. SonCW,KimKW,KimCH.Studyonexpressionofglycosa-minoglycaninadenoidcysticcarcinoma.JKoreanAssocOralMaxillofacSurg2004;30:271-81.

membranous10.Themostcommonvariantisthesolidtype,

buteachtumorhascombination-typevariants10.BCAconsists

of2 typesofcells10:one isasmallcellwith insufficient

cytoplasmandround-shapednucleus10,andtheothertypehas

largeeosinophiliccytoplasmandovoid-shapednuclei10.

Thereare somebenignandmalignantneoplasms that

mustbedifferentiallydiagnosedwithBCA.Pleomorphic

adenomaisclinicallysimilartoBCA.Itappearsasaslowly

growing, freelymovablemass1, typicallyappearingasa

painless,firmmass10.Pleomorphicadenomaoftheparotid

glandmostlyoccurs in thesuperficial lobe,manifesting

swellingonthepreauriculararea10.Accountingfor53-77%

ofparotidtumors10,pleomorphicadenomaoriginatedwitha

mixtureofductalandmyoepithelialelements10.Incontrast,

thebasictumorpatternisveryvariable,buttheindividual

cells are rarelypleomorphic10.Whenweevaluated the

patientclinically,weeasilysupposedthat thelesiontobe

pleomorphicadenomabecauseitisthemostcommonbenign

tumorintheparotidgland.

ACCaccountsfor10%ofalltumorsinsalivaryglands5,11.

Theparotidglandareaisthemostcommonsiteinthehead

andneck5.Histopathologically,ACCcanbeclassifiedinto

threemorphologicalpatternsincludingcribriform,tubular,

and solid5.Themost important and unique feature of

ACCisthetendencyofperineural invasion,eveninearly-

stage tumors5,10. Inmostcases, thecytological typingof

ACCisdistinguishedbythedetectionoflargeglobulesof

extracellularmatrixsurroundingthebasaloidtumorcells5.

ACCshowsthemosthistologicalsimilaritiestoBCA,since

bothhavethesamedevelopmentalorigin10.Note,however,

thattheircharactersareverymuchdifferentintermsofthe

integrityofthebasallayer,numberofmitoses,andgrowth

speed. In theparotidgland,ACCis rare,accountingfor

only2-3%ofall tumors10,11.There is fairlyequalgender

distribution,althoughsomestudieshaveshownslightfemale

predilection10.

Inourcase, the lesionwasgrowingslowly,and itwas

separatedwithadjacentnormaltissue.Themasswasfirm,