USMLE题库Hepatic21-30-4-6

Hepatic题库Q21A58-year-oldCaucasianmaleisfoundtohavediffusegallbladdercalcificationasanincidentalfindingonabdominalX-ray.Hedeniesanyhistoryofsevereabdominalpainorjaundice.Hisvitalsignsarestableandphysicalexaminationisunremarkable.Youinformthepatientthat:A.ItisabenignfindingwithnoriskofseriousdiseaseB.ThefindingistypicallyassociatedwithflukeinfectionofthebiliarytreeC.ThepatientisathighriskofacutecholecystitisD.ThepatientisathighriskofgallbladdercancerE.ThepatientshouldbeworkedupforcoloncancerA21Correctanswer:DThisabdominalradiographcontainstheclassicfindingofa“porcelaingallbladder,”atermusedtodescribethebluish,brittle,calcium-ladengallbladderwallthatcandevelopinsomepatientswithchroniccholecystitis.Theporcelaingallbladderistypicallydiagnosedonradiograph,sometimesincidentally,byarimofcalciumdepositsthatoutlinethegallbladderThepathogenesisoftheconditionremainsunclear,butitisthoughtthatcalciumsaltsaredepositedintramurallysecondarytoeitherchronicirritationfromgallstonesorasacomponentofthenaturalprogressionofchronicinflammation.Althoughpatientsareoftenasymptomatic,somemaypresentwithrightupperquadrantpainorwithafirm,nontendermassintherightupperquadrant.Cholecystectomyisrecommendedforthosewithporcelaingallbladdersbecause11-33%ofthispatientpopulationwilleventuallydevelopgallbladdercarcinoma.(ChoiceA)Itwouldbeentirelyinaccuratetoadvisethispatientthatporcelaingallbladderisabenignfindingwithnoriskofseriousdisease.(ChoiceB)Flukeinfectionofthebiliarytreeisassociatedwiththeformationofbrownpigmentstones,notporcelaingallbladder.(ChoiceC)Cholelithiasis,notporcelaingallbladder,isariskfactorforacutecholecystitis.(ChoiceE)Porcelaingallbladderisassociatedwithcarcinomaofthegallbladder,notcarcinomaofthecolon.EducationalObjective:Cholecystectomyisrecommendedforthosewithporcelaingallbladdersbecause11-33%ofthispatientpopulationwilleventuallydevelopgallbladdercarcinoma.Q22A20-year-oldmalehasnoticedseveralepisodesintermittentself-resolvingjaundice.Thereisnoparticularassociationwithhissymptoms.Heisotherwisehealthyandhasnoothersymptoms.Hedoesnotusetobacco,alcoholordrugs.Completebloodcountiswithinnormallimits.LiverstudiesAlbumin4.0mg/dLTotalprotein,serum6.5g/dLTotalbilirubin2.8mg/dLDirectbilirubin2.0mg/dLAlkalinephosphatase90U/LAspartateaminotransferase(SGOT)28U/LAlanineaminotransferase(SGPT)30U/LLiverbiopsyshowsabundantpigmentinclusionsinthelysosomesoftheotherwisenormalhepatocytes.Electronspinresonancespectroscopyrevealsthatthepigmentiscomposedofpolymersofepinephrinemetabolites.Whichofthefollowingisthemostlikelycauseofhisjaundice?A.IncreasedproductionofcatecholaminesB.DefectivehepatocellularexcretionofbilirubinglucuronidesC.IneffectiveintramedullaryerythropoiesisD.ImpairedconjugationofbilirubinE.LowserumceruloplasminA22Correctanswer:BDubin-Johnsonsyndromeischaracterizedbyadefectinthehepaticexcretionofbilirubinglucuronidesacrossthecanalicularmembrane.Individualswiththisrare,benignconditionhavepredominantlyconjugatedchronichyperbilirubinemiathatisnotassociatedwithhemolysis.Grossly，theliverisstrikinglyblack.Histologicalfeaturesarenormal,thoughadensepigmentcomposedofepinephrinemetaboliteswithinthelysosomescanbesee门.Clinically,icterusisevident,thoughthephysicalexaminationistypicallyotherwisenormal.Mostpatientsareasymptomatic,withsomecomplainingofnonspecificissues(eg,fatigue,abdominalpain,weakness).Theicterusmaybesomildastoonlybecomeevidentinthecontextofatriggersuchasillness,pregnancy,ororalcontraceptiveusage.Routinelaboratorytestingisunremarkable,includingthecompletebloodcountandliverfunctionprofile.Serumbilirubinlevelsusuallyrangefrom2-5mg/dLbutcanalsobenormalorextremelyelevated(20-25mg/dL).ForthediagnosisofDubin-Johnsonsyndrometobemade,conjugatedhyperbilirubinemiawithadirectbilirubinfractionofatleast50%andanotherwisenormalliverfunctionprofilemustbepresent.ConfirmationcanbeobtainedbyevaluatingtheurinarycoproporphyrinforunusuallyhighlevelsofcoproporphyrinI.Becausethisconditionisbenign,notreatmentisnecessaryandtheprognosisisexcellent.(ChoiceA)IncreasedproductionofcatecholaminesisnotassociatedwithDubin-Johnsonsyndrome,despitethehepatocyteaccumulationofepinephrinemetabolitesinthiscondition.(ChoiceC)Ineffectiveintramedullaryerythropoiesisisseeninconditionssuchasbeta-thalassemiaandmyelodysplasia，notDubin-Johnsonsyndrome.(ChoiceD)ImpairedbilirubinconjugationisseeninconditionssuchasCrigler-NajjarsyndromeandGilbertsyndrome,notDubin-Johnsonsyndrome.(ChoiceE)ExtremelyloworabsentlevelsofserumceruloplasminareseeninWilsondiseaseandaceruloplasminemia,notDubin-Johnsonsyndrome.EducationalObjective:Dubin-Johnsonsyndromeischaracterizedbyadefectinthehepaticexcretionofbilirubinglucuronidesacrossthecanalicularmembrane.Grossly,theliverisstrikinglyblack.Histologicalfeaturesarenormal,thoughadensepigmentcomposedofepinephrinemetaboliteswithinthelysosomescanbeseen.Q23A54-year-oldCaucasianmalewithtwo-yearhistoryofstablealcoholiccirrhosisexperiencesprogressiveabdominaldistention,malaiseandanorexiadespitecompleteabstinencefromalcohol.Hehasapriorhistoryofintravenousdruguse.Hi