MORPHOLOGYClinicalassessmentofchronichepatitissometimesrequiresliverbiopsyinadditiontoclinicalandserologicdata.Liverbiopsyishelpfulinconfirmingtheclinicaldiagnosis,excludingcommonconcomitantconditions(e.g.,fattyliverdisease,hemochromatosis),assessinghistologicfeaturesassociatedwithanincreasedriskformalignancy(discussedlater),gradingtheextentofhepatocyteinjuryandinflammation,andstagingtheprogressionof scarring.Historically,histologicgradingandstagingofchronic
Chronic Hepatitis. Chronic hepatitis is defined as persis tent or relapsing hepatic disease for a period of more than http://ebooksmedicine.net todeterminationsofwhethertoattempttreatmentoftheunderlyingdisease;however,withthenew,highlyeffectivetargetedantiviraltherapiesforhepatitisC,fewerpretreatmentbiopsiesarebeingperformed.
Fig.16.13 .The morphologic changes in acute and chronic viral hepatitis are shared among the hepatotropic viruses and can be mimicked by drug reactions or autoimmune hepatitis.
Acute viral hepatitis. Grossly,liversinvolvedbymildacutehepatitisappearnormalorslightlymottled.Attheotherendofthespectrum,massivehepaticnecrosismayproduceagreatlyshrunkenliver,asdiscussedearlier.Microscopically,thereisconsiderablemorphologicoverlapinacutehepatitiscausedbyvarioushepatropicviruses.Asistypicalofmanyviralinfections,mononuclearcellspredominateinallphasesofviralhepatitis.AsubtledifferenceisthatthemononuclearinfiltrateinhepatitisAmaybeespeciallyrichinplasmacells.Mostparenchymalinjuryisscatteredthroughoutthehepaticlobuleas“spottynecrosis”orlobular hepatitis.Portalinflammationinacutehepatitisisminimalorabsent.Asdiscussedearlier,hepatocyteinjurymayresultinnecrosisorapoptosis.Intheformer,thecytoplasmappearsempty,withonlyscatteredwispsofcytoplasmicremnants,andeventualruptureofcellmembranesleadsto“dropout”ofhepatocytes.Intheirplace,collapsedsinusoidalcollagenreticulinframeworkremainsbehindalongwithscavengermacrophages.Withapoptosis,hepatocytesshrink,becomingintenselyeosinophilic,andtheirnucleibecomepyknoticandfragmented;effectorTcellsmaybepresentintheimmediatevicinity.
Insevereacutehepatitis,confluentnecrosisofhepatocytesisseenaroundcentralveins.Intheseareas,theremaybecellulardebris,collapsedreticulinfibers,congestion/hemorrhage,andvariableinflammation.Withincreasingseverity,thereiscentral-portalbridgingnecrosis,followedbyparenchymalcollapse.Initsmostsevereform,massivehepaticnecrosisandfulminantliverfailureensue.