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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: [email protected]
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
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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
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2. JunqueraL,GallegoL,deVicenteJC,FresnoMF.Bilateralparotidbasalcelladenoma:anunusualcase reportand reviewof theliterature.JOralMaxillofacSurg2010;68:179-82.
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4. EstevesAR,DibLL,deCarvalhoLV.Basalcelladenoma:acasereport.JOralMaxillofacSurg1997;55:1323-5.
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9. EllisGL,AuclairPL,GneppDR.Surgicalpathologyofthesalivaryglands.Philadelphia:Saunders;1991.
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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,