Chronic viral hepatitis.The defining histologic feature of chronic viral hepatitis is mononuclear portal infiltration.Itmaybemildtosevereandvariablefromoneportaltracttotheother.Thereisofteninterface hepatitis aswell,inadditiontolobularhepatitis,distinguishedbyitslocationattheinterfacebetweenhepatocellularparenchymaandportaltractstroma.Thehallmarkofprogressivechronicliverdamageisscarring.Atfirst,onlyportaltractsexhibitfibrosis,butinsomepatients,withtime,fibroussepta—bandsofdensescar—willextendbetweenportaltracts.Inthemostseverecases,continuedscarringandnoduleformationleadstothedevelopmentofcirrhosis,asdiscussedearlier.
Certainhistologicfeaturespointtospecificviraletiologiesinchronichepatitis.InchronichepatitisB,“ground-glass” hepatocytes (cellswithendoplasmicreticulumswollenbyHBsAg)areadiagnostichallmark,andthepresenceofviralantigeninthesecellscanbeconfirmedbyimmunostaining(
Fig.16.14 ).LiverbiopsiesinvolvedbychronichepatitisCquitecommonlyshow http://ebooksmedicine.net
Fig. 16.14 Ground-glasshepatocytesinchronichepatitisB,causedbyaccu-mulationofhepatitisBsurfaceantigen.Hematoxylin-eosinstainingshowsthepresenceofabundant,finelygranularpinkcytoplasmicinclusions;immunostaining(inset) withaspecificantibodyconfirmsthepresenceofsurfaceantigen(brown).
Fig.16.15 ).Often,hepatitisC,particularlygenotype3,isassociatedwithfattychangeinscatteredhepatocytes.BileductinjuryisalsoprominentinsomecasesofhepatitisCandmaymimicthehistologicchangesseeninprimarybiliarycholangitis(seelater);clinicalparametersdistinguishthesetwodiseaseseasily,however.
Inthealphabetofhepatotropicviruses,someeasymnemonicdevicesmaybeuseful:
Thevowels(hepatitisAandE)nevercausechronichepatitis,onlyAcutEhepatitis.
Fig. 16.15 ChronicviralhepatitisduetoHCV,showingcharacteristicportaltractexpansionbyadenselymphoidinfiltrate.
Onlytheconsonants(hepatitisB,C,D)havethepotentialtocausechronicdisease(Cforconsonantandforchronic).
HepatitisBcanbetransmittedbyblood,birthing,and“bonking”(astheysayintheUnitedKingdom).
HepatitisCisthesinglevirusthatismoreoftenchronicthannot(almostneverdetectedacutely;85%ormoreofpatientsdevelopchronichepatitis,20%ofwhomwilldevelopcirrhosis).
HepatitisD,thedeltaagent,isadefectivevirus,requiringhepatitisBcoinfectionforitsowncapacitytoinfectandreplicate.
HepatitisEisendemicinequatorialregionsandfrequentlyepidemic.
TheinflammatorycellsinbothacuteandchronicviralhepatitisaremainlyTcells;itisthepatternofinjurythatisdifferent,notthenatureoftheinfiltrate.
Patientswithlong-standingHBVorHCVinfectionsareatincreasedriskfordevelopmentofHCC.
Bacterial,Parasitic,andHelminthicInfections
A multitude of organisms can infect the liver and biliary tree, including bacteria, fungi, helminths and other parasites, and protozoa. Infectious organisms can reach the liver through several pathways:
Ascending infection, via the gut and biliary tract (ascending cholangitis)