Laparoscopic resection of a gastric schwannoma: A case report

ContentslistsavailableatScienceDirect

International

Journal

of

Surgery

Case

Reports

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

Laparoscopic

resection

of

a

gastric

schwannoma:

A

case

report

Edgar

Vargas

Flores

,

Francisco

Bevia

Pérez

,

Pablo

Ramirez

Mendoza

,

José

Arturo

Velázquez

García

,

Oscar

Alejandro

Ortega

Román

a_{DepartmentofGeneralSurgery,Hospitaldeespecialidades,CentroMédicoNacionalLaRaza,SerisyZaachilasinnúmero.ColoniaLaraza,Delegación}

Azcapotzalco,02990,D.F.,Mexico

b_{DepartmentofPathology,Hospitaldeespecialidades,CentroMédicoNacionalLaRaza,SerisyZaachilasinnúmero,ColoniaLaraza,Delegación}

Azcapotzalco,02990,D.F.,Mexico

a

r

t

i

c

l

e

i

n

f

o

Received26June2016

Receivedinrevisedform

12September2016

Accepted15September2016

Availableonline20October2016

Keywords:

Laparoscopicresection

Schwannoma

Mesenchymaltumor

Gastricschwannomacasereport

a

b

s

t

r

a

c

t

INTRODUCTION:Mesenchymaltumorsofthegastrointestinaltractareagroupspindlecelltumorswhich includegastrointestinalstromaltumors,leiomyomas,leiomyosarcomasandschwannomas(Nishidaand Hirota,2000).Schwannomasgenerallypresentasaslowandasymptomaticgrowingmassinthe gas-trointestinaltracttypicallyarisinginthegastricsubmucosaaccountingforupto0.2%ofgastrictumors (MelvinandWilkinson,1993;Sarlomo-RikalaM,Miettinen,1995).

TREATMENT:withnegativesurgicalmarginresection(asapproachedinthiscase)isconsideredthe standardtreatment.

PRESENTATIONOFCASE:A60-year-oldwomanwasreferredtoourgeneralsurgeryservicefordyspepsia. DuringherevaluationagastricmasswasincidentallyfoundonupperGIendoscopywhichshoweda sub-mucosalexophyticneoplasmatthegastricantrum.Thepatientwasdischargedfollowinganuneventful recoveryfromasuccessfulsurgicallaparoscopictumorresection.

DISCUSSION:SchwannomasarebenignneurogenictumorsthatoriginatefromSchwanncells.They com-monlyoccurintheheadandneckbutarerareintheGItract(Mennoetal.,2010).Thedifferentialdiagnosis betweengastricschwannomasandGISTscanbedifficultinthepreoperativeassessment.Withtheadvent ofimmunohistochemicalstainingtechniquesitisnowpossibletomakeadifferentialdiagnosisbasedon theirdistinctiveimmunophenotypes.GastricschwannomasareconsistentlypositiveforS-100protein andnegativeforc-kit;conversely,95%ofGISTsarepositiveforc-kitandnegativeforS-100proteininup to98to99%ofthecases.

CONCLUSION:Gastricschwannomasshouldbeincludedinthedifferentialdiagnosisofanygastric sub-mucosalmass.Negativemarginresectionasseenwiththispatientisthestandardsurgicaltreatmentas thereislowmalignanttransformationpotential.

©2016TheAuthor(s).PublishedbyElsevierLtdonbehalfofIJSPublishingGroupLtd.Thisisanopen accessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

Mesenchymaltumorsofthegastrointestinaltractareformed

byagroupoftumorsofspindlecellswhichincludegastrointestinal

stromaltumors,leiomyomas,leiomyosarcomasandschwannomas

[1].AmongtheseneoplasmsGISTsarethemostcommon,(upto

60–70%)most ofthem arisinginthestomach[2,3].

Schwanno-masgenerallypresentasaslowandasymptomaticgrowingmass

andtheyrarelyappearinthegastrointestinaltractandwhenthey

do,theycommonlyariseinthegastricsubmucosaandaccountfor

upto0.2%ofgastrictumors[4,5].Owingtheirtypical

presenta-∗_{Correspondingauthor.}

E-mailaddresses:

[email protected](E.VargasFlores),[email protected](F.BeviaPérez),

[email protected](P.RamirezMendoza),[email protected]

(J.A.VelázquezGarcía),[email protected](O.A.OrtegaRomán).

tionassubmucosalneoplasmswithspindlecellhistology,gastric

schwannomasandGISTsaremacroscopicallyalike[2,6].Both

gas-tricschwannomasandGISTsoccurpredominantlyinmiddle-aged

patients[1,5]andareclinicallysimilarpresentingnorelevant

fea-tures [1,4,7]. Gastric schwannomasare benign tumors withan

excellentprognosis[5,6,8],whereas10–30%ofGISTshave

malig-nantbehavior [1,2,9].Conventionaldiagnosticimagingmethods

willnotdifferentiatebetweenthesetwocommonmesenchymal

tumors.Indeed,imagingandendoscopicmodalitiesdonotprovide

distinctivehallmarkstomakeaprecisediagnosis[8,10].Thereisnot

enoughevidencethatimagingfeaturesalonecandiscloseagastric

schwannoma,thereforeanimmunohystochemicalstainshouldaid

thefinaldiagnosis.Inthispaper,wepresenta60-year-oldwoman

withagastricmass whounderwentlaparoscopicwedgegastric

tumorresectionunderthesuspicionofaGISTpreoperativelybut

confirmedtohaveagastricschwannomapostoperatively.

http://dx.doi.org/10.1016/j.ijscr.2016.09.014

2210-2612/©2016TheAuthor(s).PublishedbyElsevierLtdonbehalfofIJSPublishingGroupLtd.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http://

Fig.1.Upperendoscopyshowingagastricsubmucosalmassintheantrum.

Fig.2.Endoscopicultrasoundshowingahypoechogeniclesion atthegastric antrum.FeaturessuggestiveofGIST.

2. Presentationofcase

A60yearoldwomanwasreferredtoourgeneralsurgeryservice. Thereasonforherinitialvisitwasdyspepsiaasheronlycomplain wasintermittentgastricdiscomfortinresponsetosolidfoods.Her medicalhistorywassignificantfordepressionsuccessfullytreated withparoxetin withnoabnormalities found onphysical exam. Duringherevaluation,agastricmasswasincidentallyfoundon upperGIendoscopy(Fig.1)whichshowedasubmucosalexophytic

massinthegastricantrumwithnormaloverlyinggastricmucosa.

Biopsyspecimensobtainedattheendoscopyyieldedonly

unspe-cificsignsofmildinactivechronicinflammationwithoutevidence

ofmalignancy,noneoplasticorcytologicalalterationswerefound.

Asubsequentendoscopicultrasoundshowedanexophyticmass

measuring1.6×1.3cmarisingfromthegastricantrumshowing

lowechogenicity(Fig.2),EUS-guidedfineneedleaspiration(FNA)

wasperformed.Aspiratesmearsshowedspindlecelltissue

frag-mentsconsistentwiththediagnosisofGIST.AnabdominalCTscan

wasobtainedrenderingnoimportantdiagnosticinformation.After

presentingthecase atourgastrointestinalsurgicalexpertteam,

aconsensuswasreachedtoproceedwithresection.Thepatient

Fig.3.A.A2×2cmgastrictumorseenafterdissectionofgastrocolicligamentin

posteriorsurfaceofgastricantrum.B.resectionofgastrictumorwithharmonic

scalpel.

wascounseled about the surgicaloptions and offeredan

elec-tivelaparoscopicsurgicaltumorresection.Afterinformedconsent

wasobtained,thepatientwastakentotheoperatingroomwhere

she was placed in supine position under general endotracheal

anesthesia.Theabdomenwaspreppedanddrapedinasterile

fash-ion.Pneumoperitoneumwasachievedat12mmofmercury,and

fouradditionaltrocarswereplacedunderdirectvision.The

stom-achwasmobilizedbyopeningthegastrocolicligament.Following

mobilizationofthegreatercurvature,alargeexophyticmassalong

inthegastricantrumclosetothepyloruswasclearlyidentified.

We isolatedthemassfromthestomachandsuspended it with

laparoscopicintestinalnontraumaticgraspers(Fig.3).Harmonic

scalpelwasusedfordissection;wethenretrievedthespecimen

(themasswithaportionofthegastricwall)throughanendocatch

bagthroughthesupraumbilicalportandwassenttopathologyfor

analysis.Closureofthesurgicaldefectwaspromptlyaccomplished

intwoplaneswithadeepplaneofnonabsorbable(polypropylene)

suturewithsimpleinterruptedstitchesandasuperficialplanewith

Lembertinvaginatingstitches,therestoftheabdominalcavitywas

visualizedwithoutanyadditionalabnormalities.Thepatienthad

abriefinhospitaluneventfulrecovery.Thefinalpathologicstudy

revealedaneoplasticmasscomprisedofspindlecellsofvarying

lympho-Table1

Histologicpatternofgastrointestinalmesenchymalneoplasms[14].

SpindleCell Epithelioid Nested Myxoid SmallRoundBlueCells Pleomorphic

GIST GIST Gangliocytic

Paraganglioma

GIST DSRBCT Leiomyosarcoma

Desmoid PEComa Clear-cell-sarcoma-like

tumoroftheGItract

Inflammatoryfibroid polyp

Roundcellliposarcoma MPNST

Schwannoma Schwannoma Plexiform

fibromyxoma

GIST Leiomyoma/

leiomyosarcoma

Epithelioidvasculartumors Leiomyosarcoma Liposarcoma

Inflammatoryfibroid polyp

Glomus IMFT

Perineurioma Granyularcelltumor Neurofibroma

Neurofibroma Rhabdoidtumor Inflammatory pseudotumors IMFT SFT Plexiform fibromyxoma Granularcelltumor

Abbreviations:DSRBCT,desmoplasticsmallroundbluecelltumor;IMFT,inflammatorymyofibroblastictumor;MPNST,malignantperipheralnervesheathtumor;PEComa, perivascularepithelioidcelltumor,SFT,solitaryfibroustumor.

Fig.4.A.Gastricsubmucosaltumorconfinementwithoutatypia,pleomorphismor apparentmitoticactivity.Blackarrowshowinggastricepithelium,asteriskpoints outsubmucosal,whitearrowshowssubmucosalgastricschwannomaB. Character-isticspindlecellarrangementwithnuclearpalisadingseeninschwannomas.

cyticcuffingattheperipheryofthetumorandtheneoplasticcells lackedimmunoreactivitywithCD117andCD34,andwerepositive toS-100protein(Table1).

3. Discussion

Schwannomas,alsoknownasneurilemmomasorneurinomas

arebenignneurogenictumorswhichoriginatefromSchwanncells

normallylocatedasawrappingofperipheralnerves.Theoretically,

schwannomascandevelopanywherealongtheperipheralcourse

ofnerve. However,theymostcommonlyoccurintheheadand

neckbuttheyarerareintheGItract[11].Gastricschwannomas

arethemostcommonintheGItract,howevertheyaccountfor

only0.2%of allgastrictumorsand typicallyinvolvesubmucosa

andmuscularispropria[4–6].Theygrowslowlyandexophytically

astheycausesymptomsonlyinaminorityofpatients.Becauseof

thissilentgrowthaswiththepatientpresentedinourcase,these

tumorsareoftendiscoveredasanincidentalfindingonimaging

studies[8,11].Whensymptomatic,themostcommonpresenting

complain is upper GIbleeding which maybesecondary to the

growingsubmucosalmasscompromisingthebloodsupplytothe

overlyingmucosa.Theoverlyingmucosaoftheneoplasmmaygive

risetoanulcerduetoareducedthresholdtogastricacid[4,10,11].

Foragastricsubmucosalmassthemaindifferentialdiagnosisis

GIST.Althoughrare,gastricschwannomasarealsoaprimaryGI

mesenchymaltumor[6].Aftera marginclearsurgicalresection

gastricschwannomashaveanexcellentprognosis[5,6,8].

There-fore,thedifferentialdiagnosisforagastricsubmucosalmassshould

include gastric schwannomas.Nevertheless,owingthe low

fre-quencyofpresentationthediagnosticsuspicionisalsoinfrequent.

ThedifferentiationbetweengastricschwannomasandGISTscan

bedifficultinthepreoperative workup.While imaging studies

suchasultrasonography,endoscopy,andCTdemonstrateextent

of invasion, none of these modalities have shown specific

fea-tures uniqueto thesetype ofneoplasms [10–13]. Furthermore,

due totherarityof gastricschwannomas,there is limiteddata

abouttheirimagingcharacteristics.Homogeneousattenuationon

CT scan is a commonly sharedfeatureof gastric schwannomas

(notusuallypresentinschwannomasinotherpartsofthebody)

[12].Inaddition,thehomogenousenhancementpatternmayaid

indifferentiationofgastricschwannomasfromGISTswhich

fre-quentlyshowheterogeneous enhancementdue todegenerative

Table2

BasicpanelofimmunostainsusefulinthediagnosisofmesenchymaltumorsoftheGItract.[14].

GIST Leiomyoma Leiomyosarcoma Schwannoma Desmoid

KIT 95% Negative Negative Negative Rarelypositive

DOG1 ∼90% Negative 0.3% Negative Negative

CD34 70% Negative Negative Negative Negative

SMA 30%–40% ∼100% 86% Negative Negative

Desmin 1%–2% ∼100% 50%–80% Negative Negative

S100 1%–2% Negative Negative 100% Negative

Cytokeratin 1%–2% ∼20%(varieswithkeratinused) 20%–38% Rare,focal Negative

visualizedonthepatient’sCTscan.Endoscopicultrasoundofour case showed a hypoechoic mass. It seemed that spindle cells wereresponsibleofthelowechogenicity[10].Endoscopictissue

biopsiesalsoyieldedinconclusiveresultswithadiagnosticaim

towardsGIST.Asshowninthiscase,endoscopicbiopsymaynot

beadequatefordefinitivediagnosisbecausemucosal

abnormali-tiesarerarelyobservedinthesesubmucosaltumorsorbecausean

insufficientsampleisusuallyobtained[8,11].Immunophenotypes

ofmesenchymaltumorsareheterogeneousdespitemacroscopic

morphologicsimilarities.Inthepast,gastricschwannomaswere

includedintheGISTcategory[6].Schwannomasaresuccessfully

identifiedasaprimaryGItumorbasedonthepositiveS-100stain

[5,6].GISTalsobecame a distinctGIcancerdiagnosticcategory

whentheexpressionofc-kitproteininGISTcellswasdiscovered

[1,2].BeforetherecognitionofS-100antigeningastric

schwan-nomas and c-kit antigen in GISTs, theseneoplasms were most

oftenclassifiedasleiomyoma,leiomyosarcoma,orgastrointestinal

autonomic nerve tumor [1,2,5,6]. Withthe advent of

immuno-histochemicalstainingtechniques it isnow possibleto make a

differentialdiagnosisbasedontheirdistinctimmunophenotypes.

GastricschwannomasarepositiveforS-100proteinin100%ofcases

andnegativeforc-kit;conversely,mostGISTsareupto95%

posi-tiveforc-kitandnegativeforS-100proteininupto98to99%of

cases(Table2).Ourcasefulfilledtheimmunohistochemical

diag-nosisforagastricschwannoma.Thereforealaparoscopicapproach

withamarginnegativeresectionwasconsideredthetreatmentof

choiceasoneofthelessinvasivemodalitiesavailableinsurgical

domain.

4. Conclusion

This case underlines the importance of including gastric

schwannomas in the differential diagnosis when preoperative

imagingstudiesrevealasubmucosalandexophyticgastricmass.

Owingtosubclinicaltumorgrowth,diagnosisisusuallydelayed.

However,nowadaysthereisnoclearevidenceincurrent

pathol-ogyliteraturetosuggestthatgastricschwannomashavemalignant

potential.Thus, recurrent diseasehasbeen onlyobserved after

incompleteresection [4–6]. Therefore, when diagnosed or

sus-pectedcompletemarginnegativesurgicalresectionasseeninthis

caseisthecurativetreatmentofchoice.

Conflictsofinterest

Theauthorsreportnoconflictsofinterest.

Sourcesoffunding

None.

Ethicalapproval

None.

Consent

Writteninformedconsentwasobtainedfromthepatientfor

publicationofthis casereportandanyaccompanyingimages.A

copyofthewrittenconsentisavailableforreviewondemandby

theEditorinChiefofthisjournal.

Authorcontribution

EdgarVargasFlores:Writingthepaper,designanddata

collec-tion,dataanalysisandinterpretation

FranciscoBeviaPérez:Designanddatacollection,dataanalysis

andinterpretation.

PabloRamirezMendoza:Designanddatacollection,data

anal-ysisandinterpretation.

JoséArturoVelázquezGarcía:Dataanalysisandinterpretation.

OscarAlejandroOrtegaRomán:Dataanalysisand

interpreta-tion.

Guarantor

EdgarVargasFlores.

Acknowledgements

Toallofmyteachersintheartofsurgery,myfriends,mymother

andbrother_...Thankyouforyourunconditionalsupport.

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