Skin. Characteristicerythemaaffectsthefacealongthebridgeofthenoseandcheeks(thebutterfly rash)inapproximately50%ofpatients,butasimilarrashalsomaybeseenontheextremitiesandtrunk.Urticaria,bullae,maculopapularlesions,andulcerationsalsooccur.Exposuretosunlightincitesoraccentuatestheerythema.Histologicallytheinvolvedareasshowvacuolardegenerationofthebasallayeroftheepidermis(
Fig.5.25A ).Inthedermis,thereisvariableedemaandperivascularinflammation.Vasculitiswithfibrinoidnecrosismaybeprominent.Immunofluorescencemicroscopyshowsdepositsofimmunoglobulinandcomplementalongthedermoepidermaljunction(
Fig.5.25B );thesealsomaybepresentinuninvolvedskin.ThisfindingisnotdiagnosticofSLEandissometimesseeninsclerodermaanddermatomyositis.
Joints. Jointinvolvementistypicallyanonerosivesynovitiswithlittledeformity,whichcontrastswithrheumatoidarthritis.
Central Nervous System. AlthoughitwassuggestedinthepastthattheneuropsychiatricmanifestationsofSLEmaybeduetoacutevasculitis,inhistologicstudiesofthenervoussysteminsuchpatients,significantvasculitisisrarelypresent.Instead,noninflammatoryocclusionofsmallvesselsbyintimalproliferationissometimesnoted,whichmaybeduetoendothelialdamagecausedbyautoantibodiesorimmunecomplexes.
Pericarditis and Other Serosal Cavity Involvement.
Inflammationoftheserosalliningmembranesmaybeacute,subacute,orchronic.Duringtheacutephase,themesothelialsurfacesaresometimescoveredwithfibrinousexudate.Latertheybecomethickened,opaque,andcoatedwithshaggyfibrous
Fig. 5.25 Systemiclupuserythematosusinvolvingtheskin.(A)AnH&E-stainedsectionshowsliquefactivedegenerationofthebasallayeroftheepidermisandedemaatthedermoepidermaljunction.(B)AnimmunofluorescencemicrographstainedforIgGrevealsdepositsofIgalongthedermoepidermaljunction.(A,Courtesy of Dr. Jag Bhawan, Boston University School of Medicine, Boston, Massachusetts. B,Courtesy of Dr. Richard Sontheimer, Department of Dermatology, University of Texas Southwestern Medical School, Dallas, Texas.) tissuethatmayleadtopartialortotalobliterationoftheserosalcavity.Pleuralandpericardialeffusionsmaybepresent.
Cardiovascular system involvementmaymanifestasdamagetoanylayeroftheheart.Symptomaticorasymptomaticpericardialinvolvementispresentinupto50%ofpatients.Myocarditisislesscommonandmaycauserestingtachycardiaandelectrocardiographicabnormalities.Valvular (so-called“Libman-Sacks”) endocarditis wasmorecommonpriortothewidespreaduseofsteroids.Thissterileendocarditistakestheformofsingleormultiple1-to3-mmverrucousdeposits,whichmayformoneithersurfaceofanyheartvalve,distinctivelyoneithersurfaceoftheleaflets(
Fig.5.26 ).Bycomparison,thevegetationsininfectiveendocarditisarelarger,whilethoseinrheumaticheartdisease(Chapter11)aresmallerandconfinedtothelinesofclosureofthevalveleaflets.