NK/T細胞淋巴瘤包括：結外NK/T細胞淋巴瘤，鼻型侵襲性NK細胞白血病慢性NK細胞淋巴增生性疾病NK細胞的免疫表型特點

DiscrepancyofCD3expression

inNKcellsCD3isaTCR-associatedcomplexFormedby6chains:,,2,2NKcellshavecytoplasmicor,butcannotassembleintactCD3complexConventionalCD3antibodydetectschain“cytoplasmicCD3”SurfaceCD3(asdetectedbyLeu4/OKT3)byflowcytometryoronfrozentissueisNEGATIVETCRLeu4,OKT3結外NK/T細胞淋巴瘤，鼻型

大多數病例為EBV（+）、CD56（+）的NK細胞表型，而少數病例具有EBV（+）、CD56（-）的細胞毒性T細胞表型。MorphologicfeaturesSurfacesquamousepitheliumcanshowfloridpseudoepitheliomatoushyperplasiaEntrappednasalmucosalglandsoftenshowclearcellchangeSkin:infiltrateoftenperivascularandperiadnexal,butsometimesdiffusedermal;subcutiscanbeinvolvedIntestine:UlcerationandperforationcommonSkinIntestineTestisMuscle結外NK/T細胞淋巴瘤的免疫表型CD2+表面CD3-;胞漿CD3+(polyclonalCD3;PS1)CD56+,CD57和CD16常-CD4,CD5,CD7,CD8:常-CD43,CD45RO:常+細胞毒顆粒+Ki67:高CD25和CD30偶爾+TCR-;CD3CD5CD56GranzymeBExtranodalNK/Tcelllymphoma:GenotypeTCRgenes:germlineinmostcasesstudiedEBVPresentinclonalepisomalformNasal:>95%positive,irrespectiveofethnicoriginExtra-nasal:>90%positiveinAsians,butlower%inCaucasiansExtranodalNK/Tcelllymphoma:MainproblemsindiagnosisBiopsiesmayshowextensivecoagulativenecrosis,renderingitimpossibletomakeadefinitivediagnosis.Repeatbiopsyisrequired.Someexamplescomprisesmallcellswithminimalcytologicatypia:distinctionfromreactivelymphoidinfiltrateverydifficultBEWARE:Mucosalsmalllymphoidcellsoftenappearslightlylargerthansmalllymphocytes,andcanshowirregularnucleiHistologicfeaturesfavoringaneoplasticprocessAbnormalarchitecture:DenseexpansileinfiltratewithwideseparationandlossofmucosalglandsTissueulcerationandnecrosisEvidenceofinvasion:AngiocentricgrowthCytologicatypia:ClearcytoplasmMedium-sized;nuclearirregularities;granularchromatinReadilyfoundmitoticfiguresinasmallcelllesionImmunohistochemicalanalysis:

First-tierpanelCD20,CD3,CD56,(Ki67)NodularaggregatesofBcellsseparatedbyTcells;fewCD56+cellsReactivelymphoidinfiltrateDensesheetsofBcellsBcelllymphomaDensesheetsofCD3+CD56+cellsNK/TcelllymphomaDensesheetsofCD3+CD56-cellsReactiveorCD56-NK/TlymphomaorTcelllymphomaHowtoconfirmasuspicionof

NK/Tcelllymphoma?ImmunostainforCD56:largeclustersorsheetsofpositivecellsstronglysupportdiagnosisoflymphoma[Pitfall:herpesinfection]In-situhybridizationforEBER:largegroupsofpositivecellssupportdiagnosisoflymphomaImmunostainforKi67:Highindex(>80%)fora