USMLE题库Hepatic11-20-4-6

Hepatic题库Q11Lightmicroscopyofaliverbiopsysampleshowsextensivelymphocyteinfiltrationandgranulomatousdestructionofinterlobularbileducts.Thebiopsywasmostlikelytakenfromwhichofthefollowingpatients?A.A45-year-oldobesefemalewithfeverandaprolongedepisodeofsevererightupperabdominalpainafterfattymealingestionB.A38-year-oldCaucasianmalewithalonghistoryofulcerativecolitiswhopresentswithfatigueandelevatedalkalinephosphataseC.A65-year-oldCaucasianfemalewithweightloss,abdominaldiscomfort,jaundiceandanepigastriummassD.A45-year-oldCaucasianfemalewithlonghistoryofpruritusandfatiguewhodevelopedpalestoolandxanthelasmaE.A35-year-oldhomelessmalewithfever,abdominalpainandjaundiceA11Correctanswer:DPrimarybiliarycirrhosis(PBC)isachronicliverdiseasecharacterizedbyautoimmunedestructionoftheintrahepaticbileductsandcholestasis.Theconditionpresentsmostcommonlyinmiddle-agedwomenandisinsidiousinonset.Pruritusisusuallythefirstsymptomandmaybeverysevere,especiallyatnight.Fatigueisalsooftenreported.Physicalfindingstypicallyincludehepatosplenomegalyandevidenceofcholestasis(eg,xanthelasma,palestool).Asthediseaseprogresses,jaundice,steatorrhea,portalhypertension,andosteopeniamaydevelop.HistologicfindingsofPBCincludethedestructionofinterlobularbileductsbygranulomatousinflammation“floridductlesion”)andaheavyportaltractinfiltrateofmacrophages,lymphocytes,plasmacells,andeosinophils.(ChoiceA)Amiddle-agedobesefemalewithfeverandaprolongedepisodeofsevererightupperabdominalpainafterfattymealingestionissuggestiveofacutecholecystitis(ratherthanbiliarycolic,whichistypicallybrieferandwithoutfever).(ChoiceB)Amalewithalonghistoryofulcerativecolitispresentingwithfatigueandhighalkalinephosphataseissuggestiveofprimarysclerosingcholangitis.(ChoiceC)Anolderfemalewithweightloss,abdominaldiscomfort,jaundice,andepigastricmassissuggestiveofpancreaticcancer.(ChoiceE)Ahomelessmalewithfever,abdominalpain,andjaundiceissuggestiveofacutecholangitis.EducationalObjective:Theclassicpictureofprimarybiliarycirrhosisisamiddle-agedCaucasianfemalewithalonghistoryofpruritusandfatiguewhonowdevelopspalestoolandxanthelasma(suggestiveofcholestasis).Q12Moldy’sgrainsinsomeregionsofChinacontainasubstancethatcausesaspecificG-to-Tmutationingenep53.Thepopulationintheseregionsisexpectedtobeatanincreasedriskofwhichofthefollowingdiseases?A.LungcancerB.InfectiousdiarrheaC.DilatedcardiomyopathyD.LivercancerE.CongenitalheartdefectsF.HypothyroidismG.OsteoporosisH.PancreaticcancerA12Correctanswer:DWhenthehumidityandtemperaturearefavorable,specificstrainsofthefungiAspergillusflavusandAspergillusparasitisusgrowonfoodssuchascom,soybeans，andpeanuts，producingaflatoxinsasabyproduct.TheseaflatoxinsarecategorizedasA1,B2?G1,andG2,withaflatoxinB1themostcommonandmosttoxic.Highlevelsofdietaryaflatoxinintakehavebeenstronglyassociatedwithhepatocellularcarcinoma.IncertainareaswithinAsiaandAfricawhereaflatoxinB1exposureishigh,p53mutationshavebeenidentifiedinmostindividualswhodevelopedhepatocellularcarcinoma.Morethan90%oftheseaflatoxin-inducedp53mutationsareaclassicG:C--T:Atransversionincodon249.Inaddition,researchsuggeststhatthecombinationofchronicaflatoxinexposureandhepatitisBinfectionsignificantlyincreasestheriskofdevelopinghepatocellularcarcinoma.(ChoicesA,B,C,E,F,G,andH)Lungcancer,infectiousdiarrhea,dilatedcardiomyopathy,congenitalheartdefects,hypothyroidism,osteoporosis,andpancreaticcancerarenotassociatedwithaflatoxin-inducedmutationofthep53gene.EducationalObjective:HighlevelsofdietaryaflatoxinexposureisassociatedwithaG:C—T:Atransversionincodon249ofthep53gene,amutationthoughttogreatlyincreasetheriskofdevelopinghepatocellularcarcinoma.Q13A46-year-oldCaucasianfemalewithsevereupperabdominalpain,vomitingandfeverisfoundtohaveaninflamedandpartiallynecroticgallbladderonlaparotomy.Whichofthefollowingeventsmostlikelyinitiatedthispatient’scondition?A.BacterialinvasionofthegallbladderwallB.IschemicdisruptionofthemucosallayerC.CysticarterythrombosisD.GallbladderoutflowobstructionE.LecithinhydrolysisandmucosaldamageA13Correctanswer:DAcutecalculouscholecystitis(ACC)ischaracterizedbyacuteinflammationofthegallbladder,initiated90%ofthetimebyobstructionofthegallbladderneckorcysticduct.Asthemostcommoncomplicationofcholelithiasis,ACCtypicallyresultsfromchemicalirritationandinflammationcausedbythepresenceofstonesinthegallbladder.Thestonesdisrupttheprotectivemucuslayer,leavingtheepitheliumexposedtothedetergentactionofthebilesalts.Prostaglandinsreleasedinthegallbladderwallfurtherinciteinflammationofthemucosaanddeepertissues,andgallbladderhypomotilityensues.Theincreasingdistentionandinternalpressurewithinthegallbladdereventuallyresultinischemia.Finally,bacteriainvadetheinjuredandnecrotictissue,causinganinfection.(ChoiceA)Bacterialinvasionofthegallbladderwallisusuallythelaststepinthepathogenesisofacutecalculouscholecystitis.(ChoiceB)Ischemicdisruptionofthemucosallayerisusuallythesecondtolaststepinthepathogenesisofacutecalculouscholecystitis.(ChoiceC)Thecysticarteryisanendartery,andthegallbladderhasnocollateralcirculation.Asaresult,vasc