Extraintestinal manifestations of Crohn disease include uveitis, migratory polyarthritis, sacroiliitis, ankylosing spondylitis, erythema nodosum, and clubbing of the fingertips, any of which may develop before intestinal disease is recognized. Pericholangitis and primary sclerosing cholangitis may occur in Crohn disease but are more common in ulcerative colitis. As discussed later, the risk for development of colonic adenocarcinoma is increased in patients with long-standing colonic Crohn disease.
Fig.15.30A ).Skiplesionsarenot granulomas(arrows).
http://ebooksmedicine.net seen(althoughfocalappendicealorcecalinflammationoccasionallymaybepresentinthosewithleft-sideddisease).Diseaseoftheentirecolonistermedpancolitis (
Fig.15.30B ).Diseaselimitedtotherectumorrectosigmoidmaybereferredtodescriptivelyasulcerative proctitis orulcerative proctosigmoiditis. Thesmallintestineisnormal,althoughmildmucosalinflammationofthedistalileum,backwash ileitis, maybepresentinseverecasesofpancolitis.
Ongrossevaluation,involvedcolonicmucosamaybeslightlyredandgranular-appearingorexhibitextensivebroad-based ulcers. Thetransitionbetweendiseasedanduninvolvedcoloncanbeabrupt(see
Fig.15.30C ).UlcersarealignedalongthelongaxisofthecolonbuttypicallydonotreplicatetheserpentineulcersofCrohndisease.Isolatedislandsofregeneratingmucosaoftenbulgeintothelumentocreatesmallelevations,termedpseudopolyps. Chronicdiseasemayleadtomucosal atrophy andaflat,smoothmucosalsurfacelackingnormalfolds.UnlikeinCrohndisease,mural thickening is absent, the serosal surface is normal, and strictures do not occur. However,inflammationandinflammatorymediatorscandamagethemuscularispropriaanddisturbneuromuscularfunctionleadingtocolonicdilationandtoxic megacolon, whichcarriesasignificantriskforperforation.
HistologicfeaturesofmucosaldiseaseinulcerativecolitisaresimilartothoseincolonicCrohndiseaseandincludeinflammatoryinfiltrates,cryptabscesses,cryptdistortion,andepithelialmetaplasia.However,skip lesions are absent, and inflammation generally is limited to the mucosa and superficial submucosa (
Fig.15.30D ).Thisdistinctionmaynotbedemonstratedbyendoscopicbiopsies,whichtypicallysamplethemucosaandlittleornosubmucosa.Inseverecases,mucosaldamagemaybeaccompaniedbyulcersthatextendmoredeeplyintothesubmucosa,butthemuscularispropriaisrarelyinvolved.Submucosalfibrosis,mucosalatrophy,anddistortedmucosalarchitectureremainasresiduaofhealeddisease,butthehistologicpatternalsomayreverttonearnormalafterprolongedremission.Granulomas are not present.
SomeextraintestinalmanifestationsofulcerativecolitisoverlapwiththoseofCrohndisease,includingmigratorypolyarthritis,sacroiliitis,ankylosingspondylitis,uveitis,skinlesions,pericholangitis,andprimarysclerosingcholangitis.