The cells of classical-type epithelioid sarcoma are typically small, uniform, and relatively bland (d). Epithelioid sarcomas typically show a mixture ...SkiptomaincontentThankyouforvisitingnature.com.YouareusingabrowserversionwithlimitedsupportforCSS.Toobtainthebestexperience,werecommendyouuseamoreuptodatebrowser(orturnoffcompatibilitymodeinInternetExplorer).Inthemeantime,toensurecontinuedsupport,wearedisplayingthesitewithoutstylesandJavaScript.AdvertisementnaturemodernpathologylongcoursearticlearticleSelectedtopicsinthepathologyofepithelioidsofttissuetumorsDownloadPDFSubjectsPathologySarcomaAbstractEpithelioidmorphology,mimickingcarcinoma,isakeyordefiningfeatureofseveralsofttissuetumorsandmaybeseeninawidevarietyofothertumors.Thisreviewwillfocusonthosetumorsdefinedatleastinpartbytheirepithelioidmorphology,inparticularepithelioidsarcoma,epithelioidmalignantperipheralnervesheathtumor,andsclerosingepithelioidfibrosarcoma.TheroleoflossoftheSMARCB1tumor-suppressorgeneinthepathogenesisoftheseepithelioidsofttissuetumorswillbediscussed,aswilltheirdifferentialdiagnosiswithnon-mesenchymaltumors,inparticularcarcinomaandmelanoma.DownloadPDFEpithelioidsarcomaEpithelioidsarcoma(ES)isadistinctivesarcomashowingepithelialdifferentiation,mostofteninvolvingthedistalextremitiesofyoungpatients.ItwasfirstformallydescribedbyEnzinger1in1970.Ithadpreviouslybeenconsideredpartofthespectrumof‘tendosynovialsarcoma’,atermpreviouslyusedtodescribewhatwenowconsidertorepresentES,clearcellsarcoma,andsynovialsarcoma.Larger,morepleomorphictumors,typicallyoccurringinmoreproximallocationshavebeenlabeled‘proximal-type’ES.Themorphological,immunohistochemical,andmoleculargeneticsofESshowsconsiderableoverlapwithmalignantextrarenalrhabdoidtumors(MERTs),asdiscussedbelow.ClinicalFeaturesClassicalESmostcommonlyoccurinadolescentsandyoungadults,withamedianageof26years.Thetumorisapproximatelytwiceascommoninmalesasinfemales.ClassicalESmostcommonlyinvolvethehands/fingers,followedbythewrist/lowerarmandlowerleg/kneebut