USMLE WORLD STEP 2 CK 1*
(INTERNAL (INTERN AL MEDICINE) MEDICINE ) *Block
BLOCK # 1
1 2 3
Internal Medicine Internal Medicine Internal Medicine
Cardiology ENT Cardiology
24 25 26
Internal Medicine Internal Medicine Internal Medicine
Respiratory Dermatology Hem!nc
4 5 6 "
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Cardiology $iostatistics Ne#rology Hepatology
2" 2% 2& 3(
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Ne#rology Cardiology R'e#matology Respiratory
% & 1( 11
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Hem!nc Hepatology Cardiology Miscellaneo#s
31 32 33 34
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
ID Cardiology ID !p't'almology
12 13 14 15
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
ID )enito#rinary R'e#matology Hem!nc
35 36 3" 3%
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Endocrinology Hepatology Cardiology Ne#rology
16 1" 1% 1&
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Cardiology Hepatology Cardiology Hepatology
3& 4( 41 42
Internal Medicine Internal Medicine Internal Medicine Internal Medicine
Hem!nc Cardiology Cardiology )enito#rinary
2( 21
Internal Medicine Internal Medicine
ENT R'e#matology
43 44
Internal Medicine Internal Medicine
)enito#rinary Cardiology
22 23
Internal Medicine Internal Medicine
Hem !nc $iostatistics
45 46
Internal Medicine Internal Medicine
ID ID
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1
USMLE WORLD STEP 2 CK 1*
(INTERNAL (INTERN AL MEDICINE) MEDICINE ) *Block
Q NO 1: A 56-y!"-ol# $%!l co%& 'o yo" o$$c $o" ' +!l!'o, o$ $!' !,# ."c& ,'ol"!,c/ S !l&o co%0l!,& o$ occ!&o,!l 0!l0'!'o,&/ 0!l0'!'o,&/ S #,& !,y c&' 0!, &y,co0 $+" o" co/ S !& ,o o3l o" ",!"y co%0l!,'&/ T" & ,o "c,' c!, , " !00'' o" 3'/ S #,& !,y %o'o,!l &'"&&o"&/ S & '!k, &'"o, "0l!c%,' '"!0y '"!0y $o" " 0o&'%,o0!&!l &y%0'o%&/ S & ! ,o,-&%ok" !,# ,o,-!lcoolc/ 4" +'!l& !" &'!l !,# & & !$"l/ 4" l,& !" cl!" 'o !&cl'!'o,/ C!"#!c !&cl'!'o, "+!l& ! &o$' S1 !,# ! lo3, -0'c# 0!,&y&'olc 0!,&y&'olc %"%" !' ' !0. '!' "!#!'& 'o ' !.ll!/ C&' .-"!y &o3& %l# ,l!"%,' o$ " c!"#!c &lo'' !,# cl!" l, $l#&/ EK & ,o"%!l/ Wc o$ ' $ollo3, & ' %o&' lkly c!& o$ " +!l+l!" #y&$,c'o, A. B. C. D. E. F. .
Rheumatic heart disease Dilated cardiomyopathy Infective endocarditis Hypertrophic cardiomyopathy Mitral annulus calcifications due to aging Ischemic heart disease Mitral valve prolapse
Explanation: !here are numerous causes of mitral regurgitation. Mitral valve prolapse is the most common cause of isolated mitral regurgitation in "orth America. All of the remaining options may cause mitral regurgitation #ut they do so much less fre$uently in this country. Rheumatic heart disease is the cause for mitral regurgitation in one third of cases and it occurs more commonly in males. Mar%ed dilatation of left ventricle& due to any cause& may lead to MR. !he proposed mechanism is the dilatation of mitral annulus and displacement of the papillary muscles. Infective endocarditis may cause acute MR #y causing damage to the valve leaflets or to the chordatendinea. Hypertrophic cardiomyopathy may cause mitral regurgitation #y systolic anterior motion of the mitral valve leaflet. Mitral annuls calcification& due to aging& usually occurs in elderly 'omen. It is a degenerative process and it may result in severe MR. Ischemia of the papilla muscle may cause transient MR. Ml may cause acute mitral regurgitation #y causing a rupture of the papillary muscle.
Educational (#)ective* Mitral valve prolapse is the most common cause of isolated mitral regurgitation in "orth America.
2
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USMLE WORLD STEP 2 CK 1*
(INTERNAL (INTERN AL MEDICINE) MEDICINE ) *Block
0"o"&&+ly Q NO 2: A 75-y!"-ol# A&!, %!l 0"&,'& 3' co%0l!,'& o$ 0"o"&&+ly 3o"&,, &o" '"o!' !,# #$$cl'y &3!llo3, $o" ' 0!&' 27 o"&/ 8o ,o'c '!' & +oc & %$$l# !,# !& &!l+! #"ool, $"o% & %o'/ 4 !l&o !& !"& &"ll c"!k, ,o& !&&oc!'# 3' "&0"!'o,/ O, .!%,!'o, $3 c"+c!l ly%0 ,o#& !" 0!l0!l 3' ',#",&& o, 0!l0!'o, o+" l!"y,./ 4& +'!l &,& !"9 PR & 1:6;%,< BP & 12:;=:%% o$ 4< RR & 22;%,< !,# T%0"!'" & >?/> C (1:>@)/ Wc o$ ' $ollo3, o"!,&%& !" ' %o&' co%%o, c!& o$ '& co,#'o, A. B. C. D. E.
H. Influen+ae and roup A ,treptococcus. Myco#acterium and Herpes simple-virus. H. influen+ae and Candida. roup A streptococcus and le#siella. roup A ,treptococcus and ,taphylococcus aureus.
Explanation: Epiglottitis is inflammation and cellulitis of the soft tissue a#ove the vocal cords glottis 'hich may cause life threatening air'ay o#struction. Epiglottitis presents 'ith rapid onset and progression of symptoms as in this patient. It presents 'ith sore throat& dysphagia& drooling& muffled voice& and cough. !he patient assumes a tripod position& sitting up on hands 'ith the tongue protruding out and head leaning for'ard. E-amination reveals cervical lymphadenopathy. ,tridor /harsh shrill noise 'ith respiration.0& laryngeal tenderness& and respiratory distress are the commonly associated signs and symptoms. ,ome common causes of epiglottitis are as follo's* H. Influen+a type B is the most common cause in children and adults. ,treptococci group A is the second most common cause in adults. ,treptococcus pneumoniae. H. 1arainfluen+a. . 1neumoniae. Candida al#icans. ,taphylococcus aureus. ". Meningitidis. 2aricella +oster.
H. influen+a and group A streptococcus are the most common causes of epiglottitis in adults. Incidence is particularly higher in countries 'here they do not vaccinate against H. Influen+a. Indirect laryngoscopy is considered to #e the #est for diagnosis. Immediate intu#ation may #e re$uired in patients 'ith severe air'ay o#struction. Anti#iotics& anti pyretics& racemic epinephrine& and steroids are the drugs of choice. Regardless of the cause& all incidences of epiglottitis are considered serious medical emergencies. Differential diagnosis of epiglottitis consists of croup& angioedema& candidiasis& anaphyla-is& diphtheria& foreign #ody aspiration& peritonsillar a#scess& and pharyngitis. /Choice B& C& D and E0 Myco#acterium& herpes simple-virus& candida& le#siella and staphylococcus aureus are rare causes of epiglottitis. Educational (#)ective* H. influen+ae and roup A ,treptococcus are the most common causes of epiglottitis.
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3
USMLE WORLD STEP 2 CK 1*
(INTERNAL (INTERN AL MEDICINE) MEDICINE ) *Block
Q NO 3: A >6-y!"-ol# $%!l 0"&,'& 'o ' %",cy "oo% co%0l!,, o$ c&' 0!, '!' &'!"'# &##,ly 3l & 3!& &o00, !' ' %!ll/ S !l&o "0o"'& &o"',&& o$ "!' 0!l0'!'o,& !,# #!0o"&&/ T 0!, & "'"o&'",!l !,# "!#!'& 'o ' l$' !"%/ T" !" ,o !"!+!', !"!+!', o" "l+, $!c'o"&/ O, "+3 o$ &y&'%& ' 0!',' "0o"'& !+, !# ! ",,y ,o& &o" '"o!' !,# #"y co $o" ' 0!&' > #!y&/ 4" 0!&' %#c!l &'o"y & &,$c!,' $o" 0!,c !''!ck& $o" 3c & '!k& 0!"o.', !,# #y&$,c'o,!l '", l#, l#, $o" 3c & '!k& &'"o,/ 4" $!%ly &'o"y & &,$c!,' $o" ' &##, #!' o$ " $!'" !' ! 77 $"o% ! !"' !''!ck/ Soc!l &'o"y "+!l& '!' & !& &%ok# o, 0!ck o$ c!"''& 0" #!y $o" ' 0!&' 15 y!"&/ Wc o$ ' $ollo3, & ' %o&' !00"o0"!' ,'!l '"!0y $o" '& 0!',' A. B. C. D. E. F.
3ora+epam Heparin Aspirin I#uprofen Acetaminophen (-ycodone
Explanation: !his vignette descri#es a 456year6old 'oman 'ith a hi sto' of panic attac%s 'ho presents 'ith sudden6onset chest pain& dyspnea& and diaphoresis. Despite her psychiatric history and relatively young age& a thorough evaluation for an acute coronary event is necessary #ecause she has multiple cardiac ris% factors. First& she has a positive family history for acute coronary syndrome at a young age. Additionally& she has a longstanding personal history of smo%ing and is ta%ing estrogen therapy& factors 'hich together dramatically increase her ris% of throm#osis. !his ris% is increased further given that she is 7 48 years of age. Myocardial infarction is pro#a#le in this patient9 thus aspirin should #e administered as soon as possi#le. Aspirin therapy has #een sho'n to greatly decrease the mortality associated 'ith acute coronary events. Even if this episode turns out not to have #een an acute coronary event& one aspirin 'ould not #e detrimental. /Choice B0 1ulmonary em#olism is possi#le& especially in light of this patient:s ris% factors for throm#osis /smo%ing& estrogen treatment& age0. Ho'ever& her clinical presentation is some'hat atypical thus further 'or%6up is re$uired #efore heparin can #e administered.
Educational (#)ective* Chest pain in a young person 'ith cardiovascular ris% factors 'arrants a thorough cardiac 'or%6up. Aspirin should #e the first drug administered 'hen suspicion of a coronary artery event is high due to its a#ility to prevent platelet aggregation and coronary spasm.
4
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USMLE WORLD STEP 2 CK 1*
(INTERNAL (INTERN AL MEDICINE) MEDICINE ) *Block
5>-y!"-ol# C!c!&!, 3o%!, co%& 'o ' 0y&c!, $o" ! Q NO 4: A 5>-y!"-ol# "o', !l' %!,',!,c .!%,!'o,/ Rc,'ly & ,o'c# ! %l# !,# '"%o" 3l 0"$o"%, &o% $, '!&k& lk 0o", o' ' '!/ S &!y& '!' ' '"%o" #&!00!"& $o" ! 3l !$'" #",k, ! l!&& o$ 3,/ 4" 0!&' %#c!l &'o"y & ,&,$c!,'/ 4" loo# 0"&&" & 16:;?: %%4 !,# !"' "!' & =:;%,/ Py&c!l .!%,!'o, & ,&,$c!,'/ Wc o$ ' $ollo3, %#c!'o,& & ' &' coc 'o '"!' '& 0!','& y0"',&o, A. B. C. D. E.
1ropranolol 2erapamil Amlodipine Hydrochlorothia+ide Enalapril
Explanation: !his patient presents 'ith hypertension and a #enign essential tremor. An essential tremor is characteri+ed #y a postural tremor /not a resting tremor unli%e 1ar%inson:s disease0 and usually distur#s the performance of fine motor tas%s. ,ometimes& it runs in families 'ith autosomal6dominant inheritance. !he pathophysiologic #asis of this condition is unclear. !he inhi#ition of the tremor #y a small amount of alcohol is typical. 1ropranolol& a non6selective #eta6#loc%er& is effective in reducing the tremor pro#a#ly #y #loc%ing #eta6; receptors. !herefore& administering propranolol to this patient 'ould help to control #oth the hypertension and the essential tremor. (ther anti6hypertensive medications& li%e thia+ide diuretics /Choice D0& calcium antagonists /Choices B and C0& and ACE inhi#itors /Choice E0& do not affect a #enign essential tremor.
Educational (#)ective* 1ropranolol is the drug of choice in patients 'ho present 'ith hypertension and a #enign essential tremor.
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5
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 5: Co,&c'+ "!#,& o$ 0l%o,!"y c!0ll!"y 3# 0"&&" (PCWP) 3" o'!,# $"o% ! 0!',' , ' I,',&+ C!" U,' (ICU) &, ! S3!,-!, c!''"/ T "!#,& !" 2: %%4 22 %%4 21 %%4 22 %%4 !,# 1= %%4/ Wc o$ ' $ollo3, & ' %#!, o$ ' +!l& +, !o+ A. B. C. D. E.
<= mmHg ;> mmHg ;< mmHg ;; mmHg ;>.5 mmHg
Explanation: It is important to %no' the difference #et'een the measures of central tendency. !he median of a dataset is the num#er that divides the right half of the data from the left half. In this case& ;< mmHg is in the middle of the dataset9 therefore& it is the median. If the num#er of o#servations is even& finding the median #ecomes tric%y. ?ou should find the middle t'o values& add them together and divide #y t'o. /Choices A and B0 are not measures of the center in this dataset. /Choice E0 !o find the mean of a dataset& you should add all the o#servations and divide that sum #y the num#er of o#servations. In this case& the mean is e$ual to ;>.5 mmHg. /Choice D0 Another measure of the center of a dataset is the mode. Finding the mode is the easiest. !he mode is the most fre$uent value of a dataset. In the scenario descri#ed& the mode is ;; mmHg.
Educational (#)ective* !he median is the value that is located in the middle of a dataset. It divides the right half of the data from the left half.
6
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 6: A 12-y!"-ol# %!l cl# co%& 'o ' o$$c !$'" , "$""# $o" ! %#c!l +!l!'o,/ 4& &cool '!c" &!y& '!' !& ! 0"ol% co,c,'"!', #", cl!&&/ 4 &'!"& , &0!c $o" ! $3 &co,#& &+"!l '%& ! #!y !,# !00!"& 'o'!lly !&o"# , & 'o'&/ 4 & ,o' #&"0'+ , cl!&& ' !00!"& $o"'$l/ T" & ,o &'o"y o$ '"!%! ,$c'o, o" 0"ol%& !' "'/ O, .!%,!'o, ' cl# & !l"' 3' &'!l +'!l &,&/ T" & ,o lo&& o$ %o'o" o" &,&o"y 0"c0'o,/ Wc o$ ' $ollo3, c!, co,$"% ' 0!','& #!,o&& A. B. C. D. E.
C! scan of the head EM studies EE studies 1sychiatric evaluation 3um#ar puncture
Explanation: A#sence /petit mal0 sei+ures are characteri+ed #y a sudden cessation& 'ithout 'arning& of ongoing mental activity. Each episode rarely lasts longer than 4> seconds. Minor motor symptoms are common& #ut compleautomations and clonic activities do not occur. !he return of consciousness is a#rupt& and there is no postictal somnolence or confusion. !he condition is diagnosed #est 'ith EE studies. An EE 'ith activation procedures /hyperventilation& photic stimulation& sleep0 helps in further diagnosis and classification of sei+ures. /Choice A0 C! scan is generally not done for all sei+ures. C! scan is recommended if there is suspicion of an associated tumor& #leed or aneurysm& or if the patient has an une-plained first sei+ure. For those 'ith une-plained first sei+ures and normal C! findings& a follo'6up study at 465 months is advisa#le. In this case& the characteristic history of petit mal sei+ures does not 'arrant a C! scan. /Choice B0 EM studies are used to diagnose peripheral nerve disorders. EM is used to analy+e the neuromuscular system& differentiate diseases of neuromuscular system from primary neuropathies. It does not help in the evaluation of sei+ure disorders. /Choice D0 At this point& a psychiatric evaluation is not the #est ne-t step in management. !here have #een many instances in 'hich petit mal 'as misdiagnosed for a psychiatric disorder& and patients 'ere treated erroneously 'ith medications. For these reasons& it is essential that this child #e thoroughly evaluated for a neurologic disorder first. /Choice E0 A lum#ar puncture is indicated in all patients 'hen an infection is #eing suspected. In the a#ove patient 'ith a classic presentation of petit mal sei+ures& a lum#ar puncture is not indicated
Educational (#)ective* 1etit mal sei+ures are characteri+ed #y a sudden cessation of mental activity. An episode is very short& #ut may occur repeatedly throughout the day. !here are no associated comple- automatisms or tonic6clonic activity. !he diagnosis is #est confirmed #y EE studies.
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7
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 7: A 75-y!"-ol# M.c!, %!l co%& 3' $+" !,o".! !,# "' 00" !#"!,' 0!,/ @o" ' 0!&' 12 #!y&/ T 0!, "!#!'& 'o ' "' &ol#" '0 !,# & !"!+!'# y #0 ,&0"!'o,/ T 0!',' +& ' &'o"y o$ loo#y #!""! &. %o,'& !o !$'" "'",# $"o% ! '"0 'o M.co/ 4 !& ,o o'" %!o" ll,&&& !,# ,+" !# !,y &""y/ 4 #,& !,y clo& co,'!c'& 3' !,%!l& & ! ,o,-!lcoolc ,o,-&%ok" !,# 3' ! &,l %o,o!%o& &.!l 0!"',"/ O, .!%,!'o, !& "' 00" !#"!,' !#o%,!l !,# ,'"co&'!l ',#",&& ' ,o !,#c/ A, l'"! &o,o"!% o$ !#o%, &o3& ! &,l ', 3!ll ,$o"% cy&' o, ' &0"o" &"$!c o$ ' "' lo o$ & l+"/ W!' & ' %o&' lkly #!,o&& , '& 0!',' A. B. C. D. E.
1yogenic liver a#scess Ame#ic liver a#scess Hydatid cyst 3iver carcinoma Hepatic adenoma
Explanation: !his patient has an ame#ic liver a#scess. !he history of travel to an endemic area follo'ed #y dysentery and right upper $uadrant pain 'ith a single cyst in right lo#e of liver is indicative of ame#ic liver a#scess. Ame#iasis is a proto+oal disease caused #y Entamoe#a histolytica. !he primary infection is in the colon leading to #loody diarrhea9 ho'ever the ame#a may #e transported to the liver #y portal circulation thus leading to an ame#ic liver a#scess /Choice B0. Ame#ic liver a#scesses are generally single and are located usually in the right lo#e. An a#scess on the superior surface of liver can cause a pleuritic6li%e type of pain and the radiation to the shoulder. !he diagnosis can #e made #y stool e-amination for tropho+oites& serology& and liver imaging. !he aspirate from the ame#ic liver a#scess is usually sterile. !reatment is 'ith metronida+ole. /Choice A0 1yogenic liver a#scess should #e considered in the differential diagnosis of ame#ic liver a#scess. But this patients history is more suggestive of ame#ic liver a#scess. 1yogenic liver a#scess is generally secondary to surgery& a gastrointestinal infection& or acute appendicitis. !he condition of the patient 'ould #e more severe than in ame#ic liver a#scess. /Choice C0 A hydatid cyst is usually caused #y an infection 'ith Echinococcus granulosus& 'hich is ac$uired #y intimate contacts 'ith dogs. /Choice D0 @nilocular cystic lesion as a presentation of hepatic adenocarcinoma is not common. Cystic carcinoma generally has thic% irregular and hyper vascular 'alls 'ith numerous septa. !he other inflammatory features are unli%ely to #e present 'ith carcinoma. /Choice E0 Hepatic adenoma is a solid lesion and not a cystic lesion.
Educational (#)ective* Entamoe#a histolytica is a proto+oan& 'hich can cause ame#ic liver a#scess. Remem#er the Me-ico trip.
8
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 8: A ;86year6old African American 'oman presents 'ith a photo distri#uted s%in rash and arthralgias. ,he is found to have lo'6range proteinuria and a#normal urinary: sediment. Renal #iopsy findings are consistent 'ith focal proliferative glomerulonephritis. Her complete #lood count sho's* Erythrocyte count 4.; mlnmm 1latelets 5>&>>>mm 3eu%ocyte count ;8>>mm hich of the follo'ing is the most li%ely cause of these hematologic findings
A. B. C. D. E.
Bone marro' hypoplasia Ineffective hemopoiesis A#normal pooling of #lood cells 1eripheral destruction of #lood cells Dilutional pancytopenia
Explanation: !he patient descri#ed in this clinical vignette displays a num#er of symptoms characteristic for systemic lupus erythematosus /,3E0. !his chronic autoimmune disorder affects mostly 'omen of child#earing age. Blac% 'omen have a higher ris% of developing ,3E than Caucasian and Asian 'omen. Hematologic a#normalities are common in patients 'ith ,3E. !hey occur due to formation of anti#odies against #lood cells and represent a form of type II hypersensitivity reaction. Anemia in ,3E is caused #y autoimmune hemolysis& and develops due to formation of 'arm Ig anti#odies to RBCs. Itis characteri+ed #y spherocytosis& a positive direct Coom#s test& and e-travascular hemolysis. !he pathogenesis of ,3E6associated throm#ocytopenia is identical to that of I!19 anti#odies against platelets are formed causing destruction of platelets. "eutropenia due to anti#ody6mediated destruction of BCs also occurs& #ut this is less common. /Choice A0 Bone marro' hypoplasia or aplasia occurs due to e-posure to environmental to-ins& certain medications /antimeta#olites& chloramphenicol0& infectious agents /parvovirus0 or as an inherited condition /Fanconi anemia0. /Choice B0 Ineffective hematopoiesis refers to #lood cell #rea%do'n in #one marro' #efore release into the circulation. !halassemias and myelodysplastic syndrome are the e-amples of such conditions. /Choice C0 Hypersplenism can result in a#normal pooling of #lood cells in the spleen 'ith su#se$uent destruction of these cells. It manifests 'ith pancytopenia and splenomegaly& and may occur in cirrhosis& malaria& sic%le cell disease and many other disorders. /Choice E0 Dilutional pancytopenia can occur after a massive pac%ed red #lood cell transfusion or massive infusions of crystalloid solutions due to increased plasma volume out of proportion to the num#er of #lood cells.
Educational (#)ective* 1ancytopenia /decreased RBC& BC and platelets0 is common in patients 'ith ,3E. It occurs due to the formation of autoanti#odies against #lood cells& a form of type II hypersensitivity reaction.
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9
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 9: A 8;6year6old male presents to his primary care physician complaining of dar% urine and feeling very itchy all over. Further in$uiry reveals that he also has #een e-periencing episodes of right upper $uadrant pain that a'a%ens him from sleep and lasts for ;6G hours at a time. He says that the pain radiates to his right scapula and is severe& dull& and constant. His medical history is significant for hypothyroidism managed 'ith medication and a remote cholecystectomy. He has smo%ed half a pac% of cigarettes per day since high school and drin%s alcohol on social occasions. He does not use illicit drugs. 3a#oratory evaluation includes the follo'ing* 3iver studies !otal #iliru#in 8.; mgd3 Direct #iliru#in G.< mgd3 Al%aline phosphatase G88 @3 Aspartate aminotransferase /A,!I ,(!0 => @3 Alanine aminotransferase /A3!& ,1!0 <>< @3 A sphincter of (ddi spasm is suspected #ased on his symptoms and history. An endoscopic retrograde cholangiopancreatography /ERC10 'ith sphincterotomy is performed. !'o days later& the patient:s #iliru#in #egins to decrease& #ut imaging reveals air 'ithin in the #iliary tree. hat is the most li%ely cause of this finding
A. B. C. D. E.
"ormal finding after ERC1 Acute pancreatitis Biliary infection 'ith gas6forming #acteria angrenous cholecystitis Biliary enteric fistula
Explanation: Endoscopic retrograde cholangiopancreatography/ERC10 is one of the most sensitive and specific tools for imaging the #iliary system& and is particularly useful if therapeutic intervention is planned. It is typically used to e-plore the common #ile duct& to clear stones from the common #ile duct& to sample tissue for diagnostic purposes& to relieve sphincter of (ddi dysfunction #y incising the musculature& and to palliate #iliary o#struction 'hen surgery is not planned. Ho'ever& the procedure is not 'ithout ris% 'ith an overall complication rate of 86<> and a mortality rate of <.8. ,ome of the more common complications of ERC1 include pancreatitis& perforation /resulting in #iliary enteric fistula& especially after sphincterotomy0& #iliary peritonitis& sepsis& hemorrhage& and adverse effects from the contrast. sedative& or anticholinergic agents. iven this patient:s presentation& then& it is most li%ely that he has a #iliary enteric fistula secondary to perforation during the ERC1 procedure. ,urgical correction of the condition is indicated. /Choice A0 Certain procedures /e.g.& the air insufflation test for infertility0 can result in the finding of free air under the diaphragm& #ut this is not the case 'ith ERC1. /Choice B0 Acute pancreatitis is a %no'n complication of ERC1 #ut 'ill not cause the appearance of gas in the #iliary tree. 1ancreatitis occurs in appro-imately 8 of all patients undergoing ERC1 and is seen in up to ;8 of patients 'ho are undergoing ERC1 for sphincter of (ddi dysfunction specifically. /Choice C0 Biliary infection 'ith gas6forming #acteria 'ill create shado'ing 'ithin the #iliary tree and 'ill cause the patient to loo%
10
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
very to-ic. Because the patient in this scenario under'ent ERC1 t'o days ago& ho'ever& an iatrogenic cause is much more li%ely. /Choice D0 angrenous cholecystitis 'ill cause the formation of gas 'ithin the gall#ladder& not the #iliary tree. In addition& patients 'ith this condition are septic. Educational (#)ective* (ne of the %no'n complications of ERC1 is an iatrogenic #iliary enteric fistula characteri+ed #y the presence of air in the #iliary tree. (ther complications include pancreatitis& #iliary peritonitis& sepsis& hemorrhage& and adverse effects from the contrast& sedative& or anti cholinergic agents.
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11
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 10: A 75-y!"-ol# "c,'ly %"!'# M.c!, $!"%" co%& 'o yo" o$$c c!& o$ #y&0,! !,# $!' &,c l!&' 2 %o,'&/ 4& +'!l &,& !" BP9 126;=:%% 4 PR9 =:;%, RR9 16;%, !,# T%0"!'"9 > C (?= @)/ O, .!%,!'o, !& 0#!l #%! l+!'# l!" +,o& 0"&&" 3' 0o&'+ K&&%!l& &, !,# ,c"!&# !#o%,!l "' 3' $" $l#/ A&cl'!'o, "+!l& "#c# ,',&'y o$ !0. !' 3' !, !"ly !"' &o,# $ollo3, S2/ Fl!" +,o& 0"&&" '"!c, &o3& 0"o%,,' . !,# Gy #&c,'/ Wc o$ ' $ollo3, & ' %o&' lkly c!& $o" '& 0!','& &y%0'o%& A. B. C. D. E.
Cor pulmonale !u#erculosis 2iral infection 1sittacosis 1neumoconiosis
Explanation: !he diagnosis in this patient is constrictive pericarditis. Constrictive pericarditis results from o#literation of pericardial space and fi#rosis of pericardium follo'ing an acute fi#rinous or serofi#rinous pericarditis or chronic pericardial effusion. !u#erculosis is a very common cause of constrictive pericarditis& especially in developing countries. !his patient is a recently migrated Me-ican farmer& 'hich puts !B on the top of the list of differentials for his constrictive pericarditis /(ption E0. ,ome other causes of constrictive pericarditis are idiopathic /G; in @,A0& post radiotherapy /4< in @,A0& post surgical /<<0& connective tissue disorders& neoplasm& uremia& sarcoidosis& etc. Constrictive pericarditis 'ill lead to ina#ility of ventricle to fill properly during diastole and 'ould further cause the signs and symptoms of decreased cardiac output /fatigue muscle 'asting etc0 andor signs and symptoms of venous overload li%e elevated 21& dyspnea& ascites& positive ussmaul:s sign& pedal edema& tender hepatomegaly etc. ,harp J-: and Jy: descent on central venous tracing is characteristic of constrictive pericarditis as is the presence of pericardial %noc% /early heart sound heard after ,;0. (ption D and E* !he clinical presentation of this patient is highly suggestive of constrictive pericarditis and psittacosis and pneumoconiosis are not an etiological cause of this condition. (ption A* !his patient has no finding suggestive of chronic lung disease& 'hich 'ould lead to cor pulmonale. Also cor pulmonale 'ould not cause constrictive pericarditis.
Educational o#)ective* !u#erculosis is the most common cause of constrictive pericarditis& in immigrant population. It should #e considered in patients 'ith une-plained elevation of 21 and history of predisposing condition.
12
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 11: A 72-y!"-ol# %!l 0"&,'& 'o yo" o$$c co%0l!,, o$ !ck 0!, '!' &'!"'# '3o #!y& !o !$'" c!""y, !+y 0!ck!&/ 4 #,& !,y 3!k,&& o" &,&o"y c!,& , & l&/ 4& 0!&' %#c!l &'o"y & ,&,$c!,'/ 4 & ,o' '!k, !,y %#c!'o,& !,# #,& #" !&/ 4& '%0"!'" & >6/ C (?= @) loo# 0"&&" & 12:;6 %%4 0l& & =:;%, !,# "&0"!'o,& !" 16;%,/ Py&c!l .!%,!'o, "+!l& 0!"!+"'"!l ',#",&&/ Lo3" .'"%'y 0o3" & 5;5 !,# ' #0 ',#o, "$l.& !" 2H/ B!,&k& &, & ,!'+/ S'"!'-l "!&, '&' & ,!'+ !' ?: #"&/ W!' & ' %o&' 0"o!l #!,o&& , '& 0!',' A. B. C. D. E. F. . H. I. . . 3. M. ".
Multiple myeloma An%ylosing spondylitis Compression fracture of the verte#rae 3um#osacral strain Herniated dis% Metastatic tumor Increased lum#ar lordosis ,pondylolisthesis Epidural a#scess ,pinal stenosis A#dominal aortic aneurysm Cauda e$uina syndrome !ransverse myelitis 2erte#ral #ody osteomyelitis
Explanation: 3um#osacral strain is the most common cause of #ac% pain. Itis estimated that the lifetime ris% of lum#osacral strain is close to =(. !he clinical scenario descri#ed is typical. !he pain starts acutely after physical e-ertion& and it is concentrated in the lum#ar area& usually 'ithout radiation to the thighs. 1hysical e-amination reveals local tenderness and contraction of the paraspinal muscles. A straight6 leg raising test and neurologic e-amination are typically normal. !he treatment includes ",AIDs and early mo#ili+ation. A herniated dis% /Choice E0 is characteri+ed #y acute pain that radiates to the thighs and typically #elo' the %nee. ,traight6leg raising test is positive. A compression fracture of the verte#rae /Choice C0 presents as acute intense pain& and local spinal tenderness is usually o#served. 1redisposing factors are usually o#vious /postmenopausal or senile osteoporosis& steroid treatment0. An%ylosing spondylitis /Choice B0 and multiple myeloma /Choice A0 are characteri+ed #y chronic #ac% pain. A metastatic or primary tumor /Choice F0 is not li%ely in this case.
Educational (#)ective* 3um#osacral strain is the most common cause of acute #ac% pain. !he typical clinical scenario includes acute onset of the #ac% pain after physical e-ertion& a#sence of radiation& presence of paraverte#ral tenderness& negative straight6leg raising test& and normal neurologic e-amination.
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 12: A 7>-y!"-ol# %!l 0"&,'& 'o ! 0y&c!, 3' !, lc" o, ' &!$' o$ & 0,&/ T lc" & ,o,-',#" 3' ! "!&# o"#" !,# ! &%oo' !&/ T" & l!'"!l ,,!l !#,o0!'y/ T "&' o$ ' .!%,!'o, & ,"%!"k!l/ D!"k $l# %c"o&co0y o$ ! &0c%, $"o% ' lc" !& "+!l& &0"oc'&/ Wc o$ ' $ollo3, !##'o,!l &c",, &'#& &ol# 0"$o"%# o, '& 0!',' A. B. C. D. E.
2DR3 F!A6AB, HI2 anti#odies #y E3I,A 1roctosigmoidoscopy ,erum prostate specific antigen
Explanation: !his patient:s clinical picture is consistent 'ith primary syphilis. Dar%field microscopy is especially useful in diagnosing primary syphilis& and visuali+ation of the spirochetes /as in this case0 confirms the diagnosis. !his patient:s syphilis infection suggests that he may #e involved in high6ris% se-ual activity& also putting him at ris% for HI2 e-posure. After proper counseling& HI2 screening using E3I,A should #e offered. /Choices A and B0 2DR3 and E!A6AB, #oth test for syphilis e-posure. In this case& the diagnosis has already #een confirmed #y dar%field microscopy& so there is no need for serological testing. /Choices D and E0 1roctosigmoidoscopy is a screening test for colorectal cancer& and serum prostate specific antigen is a screening test for prostate cancer. ,creening 'ith #oth tests is usually instituted at age 8>.
Educational (#)ective* no' the screening and diagnostic tests for syphilis. no' ho' to screen high6ris% patients for se-ually transmitted diseases.
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Q NO 13: A >-y!"-ol# %!, 0"&,'& 'o ' %",cy #0!"'%,' co%0l!,, o$ lo3" !#o%,!l 0!, !,# ,!&!/ 4 #,& !,y +o%', o" #!""! !,# & l!&' o3l %o+%,' 3!& '3o #!y& !o/ T 0!',' !l&o ,o'& '!' &+"!l #!y& !o !, '!k, !%'"0'yl, $o" c"o,c ,ck 0!,/ 4 #o& ,o' &%ok o" co,&% !lcool/ O, 0y&c!l .!%,!'o, & loo# 0"&&" & 16:;: %%4 !,# & !"' "!' & 1::;%,/ 4& l, $l#& !" cl!" 'o !&cl'!'o,/ P!l0!'o, o$ ' !#o%, "+!l& $ll,&& !,# ',#",&& !lo, ' %#l, lo3 ' %lc&/ Wc o$ ' $ollo3, & ' &' ,'!l %!,!%,' $o" '& 0!',' A. B. C. D. E. F.
A#dominal C! scan @pright a#dominal -6ray Barium enema Broad spectrum anti#iotics @rinary catheteri+ation I2 fluids& analgesics& and o#servation
Explanation: !his patient presents 'ith a#dominal pain and suprapu#ic fullness several days after starting amitriptyline for chronic pain. !his presentation is consistent 'ith amitriptyline6induced urinary retention. Amitriptyline is a tricyclic antidepressant 'ith anticholinergic properties. Because #oth the detrusor muscle and urethral sphincter are under muscarinic control& anticholinergic agents 'ill reduce detrusor contraction and prevent urethral sphincter rela-ation. !he result is urinary retention. @rinary catheteri+ation 'ould serve t'o purposes in this case. First& it can document a postvoid residual #ladder volume of greater than 8> ml& 'hich is considered diagnostic of urinary retention. 1lus& catheteri+ation 'ill provide symptomatic relief as it drains urine from the #ladder. !he patient should also discontinue amitriptyline therapy. /Choice A0 An a#dominal C! scan 'ould reveal a distended #ladder in this patient and may also sho' hydronephrosis. Ho'ever& C! scans are much more e-pensive and time consuming than urinary catheteri+ation and 'ill not provide symptomatic relief. /Choice B0 An upright a#dominal -6ray may sho' a distended #ladder #ut it is nota relia#le test for evaluating urinary retention. A#dominal -6rays are especially helpful for diagnosing ileus or small #o'el o#struction. /Choice C0 Barium enemas are used to diagnose luminal a#normalities of the colon& li%e colon cancer or diverticulosis. /Choice D0 Broad6spectrum anti#iotics are appropriate 'hen a urinary tract infection 'ith urinary retention is suspected. !his patient does not complain of fever& chills& or dysuria& ma%ing infection less li%ely. /Choice F0 I2 fluids& analgesics& and o#servation are the treatment for nephrolithiasis& or %idney stones. 1atients 'ith %idney stones typically present 'ith intense flan% pain and hematuria& not suprapu#ic fullness. I2 fluids 'ould actually e-acer#ate this particular patient:s symptoms. Educational (#)ective* Drugs 'ith anti cholinergic properties can cause acute urinary retention #y preventing detrusor muscle contraction and urinary sphincter rela-ation. !he treatment is medication discontinuation and urinary catheteri+ation.
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 14: A 65-y!"-ol# %!, 0"&,'& 3' &##, o,&' o$ &+" "' k, 0!, 3' $+" !,# cll&/ 4 & ! "'"# &occ" 0l!y" 3' &'o"y o$ o&'o!"'"'& ,+ol+, o' k,&/ O, $"'" &'o,, #,& !+, !,y o'" &y%0'o%&/ E.!%,!'o, o$ & k, o,' "+!l& "#,&& 3!"%' ',#",&& 3' $$&o, !,# %!"k# l%'!'o, , "!, o$ %o+%,'&/ 4& +'!l &,& !" 0l&9 =6;%, BP9 17:;?:%% 4 PR9 1=;%, !,# T%09 >=/5 C (1:2 @)/ Wc o$ ' $ollo3, 3' cll co,'& , o,' $l# !&0"!' &' co""l!'& 3' ' !o+ 0"&,'!'o, A. B. C. D. E.
48>>>u3 K>>>>u3 <8>u3 88>>>u3 G8>>>u3
Explanation: E-planation* !he sudden onset of acute monoarticular arthritis in a previously damaged )oint 'ith no other associated symptoms other than chills and fever suggests septic arthritis. !he )oint involved 'ill #e tender and erythematous 'ith large effusion. It is most commonly caused #y staphylococcus aureus. In intravenous drug a#users and immunocompromised patients& gram6negative #acteria such as E. Coli and pseudomonas aeruginosa are commonly isolated. In septic arthritis the leu%ocyte count of synovial fluid e-ceeds 8>>>> and often <>> >>>u3. ,ystemic anti#iotic therapy 'hen started promptly results in full recovers:. Choice A* Cell counts in the range of ;>>>u3 to 8>>>>u3 suggest mild to moderate inflammation as seen in rheumatoid and crystalline arthritis. Choice C* Cell counts less then ;>> are normal. Choice D 88>>>u3 and Choice E G8>>>u3 cell counts suggest gout or moderate inflammation.
Educational (#)ective* Acute inflammatory monoarticular arthritis in a previously damaged )oint suggests septic arthritis. 3eu%ocyte counts in synovial fluid e-ceeding 8>.>>> or even <>>&>>>ul should ma%e you thin% of septic arthritis.
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(INTERNAL MEDICINE) *Block
Q NO 15: A 21-y!"-ol# 0"+o&ly !l'y %!, 0"&,'& 'o yo" o$$c $o" ! "o', cck-0/ 4 !& ,o c"",' co%0l!,'&/ 4 #o& ,o' &%ok o" co,&% !lcool/ 4& $!%ly &'o"y & &,$c!,' $o" cy&'c $"o&& , & ol#" "o'"/ 4 & &.!lly !c'+ 3' o, 0!"'," !,# && co,#o%& "l!"ly/ 4 +&'& ! #,'&' '3c 0" y!"/ 4& '%0"!'" & >6/6C (?/? @) 0l& & =;%, "&0"!'o,& !" 17;%, !,# loo# 0"&&" & 12:;6 %%4/ Py&c!l .!%,!'o, "+!l& &+"!l ,o,-',#" ""y c"+c!l ly%0 ,o#& !c %!&", !00"o.%!'ly 1 c% , #!%'"/ T" & ,o 0!'o&0l,o%!ly/ Wc o$ ' $ollo3, & ' &' ,.' &'0 , %!,!%,' o$ '& 0!',' A. B. C. D. E. F.
3ymph node #iopsy Diclo-acillin 1rednisone Erythromycin Acyclovir (#servation
Explanation: !his patient has asymptomatic locali+ed lymphadenopathy. !here are multiple causes of cervical lymphadenopathy& #ut it most commonly develops in the setting of an upper respiratory infection. !he physical e-am often helps to distinguish #et'een #enign etiologies and more serious ones. ,mall& ru##ers: lymph nodes are rarely pathologic and are often found in healthy children and young adults. "odes less than < .> cm in diameter are almost al'ays due to a #enign process. In contrast& nodes associated 'ith cancer tend to #e firm and immo#ile. A nodal diameter7 ;.> cm is associated 'ith a greater li%elihood of malignancy or granulomatous disease. At this point& this patient:s lymphadenopathy can #e o#served. ,hould the patient develop symptoms /e.g.& fever& chills& or 'eight loss0 or if the nodes gro'& he should receive further evaluation. Hard cervical nodes in an older patient or smo%er 'ould prompt an investigation for metastatic cancer or oropharyngeal neoplasia. /Choice A0 Biopsy may #e re$uired if the lymph node diameter is greater than ;.> cm. /Choice B0 Diclo-acillin 'ould #e an accepta#le choice if the patient had fluctuant cervical lymph nodes& a condition typically caused #y staphylococcal or streptococcal infection. Ho'ever& it is not necessary to treat a patient 'ith asymptomatic cervical lymphadenopathy 'ith an anti#iotic. /Choice C0 ,arcoidosis can cause cervical lymphadenopathy and often responds promptly to corticosteroid therapy. !his patient does not have symptoms or generali+ed lymphadenopathy suggestive of a systemic inflammatory condition. /Choice D0 Erythromycin is a macrolide anti#iotic that is among the first6 line agents for treating streptococcal pharyngitis and mild community ac$uired pneumonia. /Choice E0 Herpes simple-virus /H,20 and varicella +oster virus /2L20 infections are treated 'ith acyclovir. !his patient does not have s%in manifestations or other symptoms to suggest infection 'ith one of these viruses. Educational (#)ective* ,mall cervical lymph nodes are a common o#servation in children and young adults. 1atients 'ith asymptomatic& soft lymph nodes can #e o#served for node gro'th or the development of symptoms.
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17
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 16: A 7-y!"-ol# 3o%!, lo&& co,&co&,&& $o" 2 %,'& 3l &o00, , ! &0"%!"k'/ I, ' %",cy "oo% & "co,'& $l, ,!&! !,# 3!"%' &0"!#, o+" " o#y %%#!'ly $o" 0!&&, o'/ S !& ,+" !# ! &%l!" 0&o# $o"/ S !& ,o' &, ! #oc'o" $o" &+"!l y!"& !,# #o& ,o' '!k !,y %#c!'o,& ,o" #o& & & 'o!cco !lcool o" #"&/ 4" $!%ly &'o"y & ,"%!"k!l/ Wc o$ ' $ollo3, %o&' lkly c!&# '& 0&o# A. B. C. D. E. F.
Cardiac arrythmia ,ei+ure "eurocardiogenic syncope Heart valve disease (rthostatic hypotension !ransient ischemic attac%
Explanation: "eurocardiogenic syncope& also %no'n as vasovagal syncope& is a common cause of fainting. It occurs due to e-cessive vagal tone and is characteri+ed #y nausea& diaphoresis& tachycardia& and pallor immediately prior to the syncopal episode. 3t fre$uently occurs in response to stress& pain& and certain #odily actions /e.g. urination0. It is particularly common in young 'omen. 2asovagal syncope can #e diagnosed 'ith the tilt ta#le test. /Choice A0 Conduction disorders /e.g. A2 #loc%0& tachyarrhythmias /e.g. ventricular or supraventricular tachycardia0& and disorders of automaticity /e.g. sic% sinus syndrome0 can all cause fainting. enerally there are no preceding signs or symptoms& e-cept for palpitations in some. 1atients usually have underlying cardiac disease. /Choice B0 ,ei+ures and syncopal episodes are sometimes difficult to distinguish. !his patient does not have clear signs of sei+ure /e.g. tongue #iting0& a history of sei+ures& or a post6ictal state& ma%ing syncope more li%ely. /Choice D0 ,yncope due to aortic stenosis most often occurs 'ith activity. Dyspnea& chest pain& and fatigue on e-ertion are symptoms of aortic stenosis that generally occur earlier in the disease course. /Choice E0 (rthostatic hypotension is defined as a drop in systolic #lood pressure greater than ;> mm Hg after the patient rises to a standing position. It is most common in the elderly& dia#etics& those 'ith autonomic neuropathy /e.g. 1ar%inson:s disease0& those 'ith hypovolemia& and people ta%ing diuretics& vasodilators& or adrenergic6 #loc%ing agents. 1rolonged recum#ence increases the ris%. 1atients commonly e-perience pre6syncopal lightheadedness. /Choice F0 !ransient ischemic attac%s /!IAs0 can produce syncope& #ut are a rare cause #ecause the !IA must affect the posterior circulation and #rain stem in order for syncope to occur. !his patient has no ris% factors for stro%e.
Educational (#)ective* "eurocardiogenic& or vasovagal& syncope occurs due to e-cessive vagal tone. Episodes are preceded #y nausea& diaphoresis& tachycardia& and pallor. 1ain& stress& and situations li%e medical needles and urination can all precipitate vasovagal syncope.
18
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 17: A >2-y!"-ol# 3o%!, 0"&,'& 'o " 0"%!"y c!" 0y&c!, co%0l!,, o$ +o%', !,# +"y #!"k yllo3 ", '!' !, $o" #!y& !o 3l & 3!& !' 3o"k/ S !##& '!' '3o o$ " &l,& !+ &%l!" &y%0'o%&/ T" 3k& !o " $!%ly "'",# $"o% ! '"0 'o I,#!/ P"o" 'o '& ' 3o%!, 3!& !l'y !,# !# ,o %#c!l co,#'o,& '!' ""# '"!'%,'/ S !& ,o k,o3, #" !ll"&/ Py&c!l .!%,!'o, "+!l& &cl"!l c'"& !,# "' 00" !#"!,' ',#",&& 3' 0!'o%!ly/ S"oloc!l '&', co,$"%& ' #!,o&& o$ 0!''& E ,$c'o,/ Wc o$ ' $ollo3, & '" !o' 0!''& @ A. Hepatitis B. Hepatitis C. Hepatitis hepatitis in D. Hepatitis E. Hepatitis
E is primarily se-ually transmitted E can #e effectively prevented #y vaccination F has a very high rate of progression to fulminant the pregnant female F infection can evolve into a carrier state F is endemic in the @nited ,tates
Explanation: Hepatitis E virus /HE20 is an R"A virus that causes an illness similar to that seen 'ith hepatitis A infection. Histologically& hepatic #iopsy in this patient population reveals focal necrosis& #allooned hepatocytes& and acidophilic hepatocytic degeneration. !ransmission of HE2 typically occurs through fecally contaminated 'ater in endemic areas 'ith person6to6person transmission rare. Hepatitis E virus has a predicta#le geographical distri#ution& and is most commonly found in India& Asia& Africa& and Central America. It is highly unusual in the @nited ,tates. Individuals aged <86G> years are most commonly infected and appear to have an incu#ation period of <865> days& 'ith a#rupt onset of symptoms. aundice& malaise& anore-ia& nausea& vomiting& a#dominal pain& fever& and hepatomegaly are the more common signs and symptoms. 3a#oratory findings include elevated serum #iliru#in& A3!& and A,!. Diagnosis is confirmed 'ith detection of HE2 R"A #y 1CR in the serum or feces or #y the detection of .86 4. More alarmingly& fulminant hepatitis occurs in <86;8 of pregnant 'omen infected 'ith hepatitis E virus& especially those in the third trimester. !here is also evidence to suggest that hepatitis E infection can #e vertically transmitted& 'ith significant perinatal mor#idity and mortality. !here is little information availa#le a#out the efficacy of immune glo#ulin in HE2 prevention& and therefore it is not typically recommended. !ravelers to endemic areas should #e advised to minimi+e e-posure to 'ater of un%no'n purity. /Choice A0 Hepatitis E is primarily transmitted via the fecal6oral route& not se-ual contact. /Choice B0 An effective HE2 vaccine is not 'idely availa#le at this time. /Choice D0 Hepatitis E virus infection does not result in a chronic carrier state. /Choice E0 Hepatitis E is very rare in the @nited ,tates and is more commonly seen in India& Asia& Africa& and Central America. Educational (#)ective*
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19
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Infection 'ith hepatitis E virus has a high rate of progression to fulminant hepatitis in pregnant 'omen& especially in the third trimester.
20
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(INTERNAL MEDICINE) *Block
Q NO 18: A 66-y!"-ol# 3' %!l 0"&,'& 'o yo" o$$c 3' ! $+ %o,' &'o"y o$ #$$cl'y 3!lk,/ 4 .0",c& "' ' 0!, 3l 3!lk, $!&' o" cl%, o, $l' o$ &'!"&/ P!, & "l+# 3' "&'/ 4& 0!&' %#c!l &'o"y & &,$c!,' $o" y0"col&'"ol%! co,'"oll# 3' &%+!&'!',/ 4 &%ok& '3o 0!ck& ! #!y !,# co,&%& !lcool occ!&o,!lly/ 4& loo# 0"&&" & 155;?5 %%4 !,# !"' "!' & :;%,/ Py&c!l .!%,!'o, "+!l& &y&'olc %"%" o+" ' "' &co,# ,'"co&'!l &0!c "' c!"o'# "' #%,&# 0l&!'o, o+" ' "' 0o0l'!l !"'"y !,# !&,' #o"&!l& 0l&!'o,& , o' l&/ Wc o$ ' $ollo3, %#c!'o,& & ' &' coc 'o co,'"ol '& 0!','& y0"',&o, A. B. C. D. E.
Hydrochlorothia+ide Metoprolol Amlodipine Enalapril Do-a+osin
Explanation: !his patient presents 'ith intermittent claudication significantly restricting his daily activities and pro#a#le asymptomatic carotid artery and aortic stenosis. An unfavora#le lipid profile and smo%ing are other ris% factors. !reatment of hypertension is very important& #ecause this patient #elongs to a high6ris% group for future cardiovascular events. !he #est initial choice for the treatment of hypertension in this patient seems to #e a dihydropyridine calcium channel #loc%er li%e amlodipine. Calcium channel #loc%ers have good peripheral vasodilating properties that can help to diminish the symptoms of intermittent claudication. !hey are also meta#olically neutral& not affecting plasma lipid profile. !hia+ide diuretics& li%e hydrochlorothia+ide /Choice A0& are not meta#olically neutral and do not affect intermittent claudication* therefore& a calcium channel #loc%er is a #etter choice for this patient. Metoprolol& a #eta6#loc%er /Choice B0& can 'orsen the symptoms of peripheral vascular disease. Beta6#loc%ers should #e stopped if the patient develops significant peripheral vascular disease. Enalapril& an ACE inhi#itor /Choice D0& can #e considered& #ut it 'ould not relieve the symptoms of intermittent claudication. Do-a+osin /Choice E0 is an alpha6#loc%er 'ith a favora#le meta#olic profile. It is not considered as a first6line drug in the treatment of hypertension& #ecause the long6term effects of alpha6#loc%er therapy are not clear. Moreover& some side effects of the alpha6#loc%er therapy may #e distur#ing /e.g.& orthostatic hypotension0.
Educational (#)ective* In patients presenting 'ith significant peripheral vascular disease& calcium channel #loc%ers are preferred as antihypertensive agents.
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 19: Wc o$ ' $ollo3, 0!',' 3ll !+ ' lo3&' "!' o$ 0"o"&&o, o$ c"o,c 0!''& C 'o 0!'c $"o&& !,# c""o&&
A. A
non6alcoholic female 'ho ac$uired hepatitis C at age of <= B. An occasional alcoholic male 'ho ac$uired hepatitis C at GG years age C. A non6alcoholic male co infected 'ith HB2 and HC2 D. A non6alcoholic female cc infected 'ith HI2 and HC2 E. A non6alcoholic male 'ho ac$uired hepatitis at age of <= Explanation: A#out 8> to > of patients 'ith acute hepatitis C progress to chronic hepatitis C regardless of the mode of ac$uisition. 1rogression of liver disease in case of chronic hepatitis C is #est assessed #y liver histology. 1rogression of liver disease in patients 'ith chronic hepatitis is relatively more rapid in follo'ing conditions* <. Male se;. Ac$uiring infection after age of G> 4. 3onger duration of infection G. Co infection 'ith HBC or HI2 8. Immunosuppression 5. 3iver co mor#idities li%e alcoholic liver disease& hemochromatosis& alpha6i anti trypsin deficiency Factors independently associated 'ith high rates of liver fi#rosis in chronic hepatitis C patients are* <. Male gender ;. Ac$uiring infection after age of G> 4. Alcohol inta%e* alcohol inta%e in any amount can hasten the progression of fi#rosis in patients 'ith chronic hepatitis C /Choice A0 ,he has the least progression of fi#rosis among the given sets of patients due to her female se-& earlier age of ac$uisition of infection& non alcoholic state& and no liver co mor#idities or infections. /Choice B0 Infection after the age of G> is an independent ris% factor for progression of fi#rosis. /Choices C and D0 Co infection 'ith hepatitis B or HI2 is a ris% factor for rapid progression of fi#rosis. /Choice E0 Although patient has infection at younger age and is a non6 alcoholic& his male se- is an additional ris% factor as compared to patient in Choice A.
Educational (#)ective* no' the ris% factors for rapid progression of liver fi#rosis in patients 'ith chronic hepatitis C.
22
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 20: A 65-y!"-ol# %!, 0"&,'& 3' co%0l!,'& o$ #c"!&# +&o, , o' y&/ 4& +&!l %0!"%,' !& , 0"o"&&+ly 3o"&,, o+" ' 0!&' $+ %o,'&/ 4 3!& #!,o&# 3' #!'& ', y!"& !o/ 4& c"",' %#c!'o,& !" %'$o"%, !,# ly"#/ 4& loo# 0"&&" & 17:;?: %% 4 0l& & =2;%, "&0"!'o,& !" 17;%, !,# '%0"!'" & ?=/7 @ (>6/== C)/ E.!%,!'o, &o3& #c"!&# +&!l !c'y , o' y&/ O0'!l%o&co0y "+!l& %c"o!,"y&%& #o' !,# lo' %o""!& !"# .#!'& !,# %!cl!" #%!/ Wc o$ ' $ollo3, & ' %o&' lkly #!,o&& A. B. C. D. E.
Central retinal vein occlusion Dia#etic retinopathy Macular degeneration Retinal detachment (pen angle glaucoma
Explanation: Dia#etic retinopathy is the leading cause of #lindness in the @,A. It occurs in #oth insulin dependent and non6insulin dependent dia#etes mellitus. !here are 4 main categories* <. #ac%ground or simple retinopathy6 consists of microaneurysms& hemorrhages& e-udates& and retinal edema. as in this patient ;. pre6proliferative retinopathy6 'ith cotton 'ool spots 4. proliferative or malignant retinopathy 6 consists of ne'ly formed vessels. 1atients are usually asymptomatic at first& despite early signs of retinopathy /e.g.& microaneurysms0. 2isual impairment occurs 'ith the development of macular edema. Argon laser photocoagulation is the suggested treatment for the prevention of complications. /Choice A0 Central retinal vein occlusion is characteri+ed #y sudden& unilateral visual impairment that is usually noted upon 'a%ing in the morning. Dia#etics are at increased ris% for retinal vein occlusion. (phthalmoscopy reveals disc s'elling& venous dilation and tortuosity& retinal hemorrhages and cotton 'ool spots. /Choice C0 Macular degeneration affects central vision. It is characteri+ed #y distorted vision and central scotoma. Cigarette smo%ing increases the ris% of macular degeneration. (phthalmoscopy findings vary according to the type /i.e.& atrophic vs. e-udative0. !he atrophic form is characteri+ed #y multiple sores in the macular region& 'hile the e-udative form is characteri+ed #y ne' #lood vessels that may lea%& #leed& and scar the retina. /Choice D0 Retinal detachment occurs unilaterally. It presents as #lurred vision that progressively 'orsens. (phthalmoscopy reveals the retina hanging in the vitreous. /Choice E0 (pen angle glaucoma is also seen in dia#etics& #ut is characteri+ed #y gradual loss of peripheral vision& resulting in tunnel vision. (phthalmoscopy sho's pathologic cupping of the optic disc.
Educational (#)ective* !he 4 main categories of dia#etic retinopathy are #ac%ground or simple /microaneurysms& hemorrhages& e-udates& retinal edema0& pre6proliferative /cotton 'ool spots0& and proliferative or malignant /neovasculari+ation0. 2isual impairment
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23
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
occurs 'ith the development of macular edema. Argon laser photocoagulation is performed for the prevention of complications.
24
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Q NO 21: A 25-y!"-ol# 3' %!l 0"&,'# 3' 0oly!"'"!l!& !,# &+" l 0!,/ 4 #&clo&& '!' !# ! &.!l ,'"co"& 3' 0"o&'''9 &,c ', &'!"'# !+, "'"!l #&c!"/ O, .!%,!'o, !ll & #'& !" #$$&ly &3oll, !,# !00!"& lk &!&!J #'&/ "!% &'!, o$ ' "'"!l #&c!" !,# o,' !&0"!'o, & ,!'+ $o" o"!,&%&/ Wc o$ ' $ollo3, & ' %o&' !00"o0"!' ,.' &'0 , ' %!,!%,' o$ '& 0!',' A. B. C. D. E.
!reatment 'ith corticosteroids !reatment 'ith ",AIDs !reatment 'ith ceftria-one IM one dose Dra' #lood cultures !reatment 'ith methotre-ate
Explanation: E-planation* !his patient is most li%ely suffering from arthritis reactive to genitourinary infection #y Chlamydia. Reactive arthritis is a form of seronegative spondyloarthropathy. !his patient also has evidence of enthesopathy that has caused heel pain and sausage digits in this patient. Enthesopathy is $uite specific for spondyloarthropathy. !he treatment of choice for reactive arthritis or Reiter:s syndrome is 'ith ",AIDs. !etracycline may #e added to them if the disease is due to genitourinary infection 'ith Chlamydia and this 'ill result in early resolution of symptoms due to anti6chlamydial and anti6inflammatory activity of tetracycline. 1atients 'ho are refractory to the a#ove treatment may #enefit from sulfasala+ine& infli-ima# and methotre-ate. !reatment 'ith IM ceftria-one is indicated 'hen there is gonococcal infection that is a gram6negative diplococcus. onococcal infection is not a cause of reactive arthritis. In cases of gonococcal infection& gram stain of the urethral discharge 'ill sho's gram6negative diplococcus. Blood cultures are not the appropriate choice in this setting since this is not a septic process.
Educational (#)ective* ",AIDs are the mainstay of treatment of Reiter:s syndromereactive arthritis.
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Q NO 22: M&/ S!lly ! 57-y!"-ol# 3o%!, co%& 'o ' o$$c 3' co%0l!,'& o$ ,c"!&# 3' , ' l!&' 7 %o,'&/ S #,& !,y c!, , !00'' o" !', !'& ' !& !,# 5: l (2/6k)/ S & o, ,o %#c!'o,& !,# & o,ly &oc!l #",k"/ S & y3 #' co,&co& !,# $ollo3& ' .!c' ,&'"c'o,& , D"/ A' k,& D' "+ol'o,J/ S &%ok& 1 0!ck;#!y c!"''& $o" ' 0!&' l6y!"&/ Py&c!l .!%,!'o, &o3& !, o& !#o%, !,# ', l& ' & o'"3& ,"%!"k!l/ @"'" 3o"k-0 co,$"%& ' #!,o&& o$ &%!ll cll c!"c,o%! o$ l,&/ Wc o$ ' $ollo3, &' o$ '&'& 3ll %o&' "l!'# 'o 0!','& 0"&,', &y%0'o%& hat 'ill #e the levels of* Cortisol& AC!H levels& 3o' Dose De-amethasone ,uppression& High Dose De-amethasone ,uppression A. B. C. D. E.
Increased& Increased& "o ,uppression& ,uppression Increased& Decreased "o ,uppression "o ,uppression Increased& Increased& ,uppression& "o ,uppression Increased& Increased& "o ,uppression "o ,uppression "ormal& "ormal& ,uppression& ,uppression
Explanation: ,ome #enign or malignant /cancerous0 tumors that arise outside the pituitary can produce AC!H. !his condition is %no'n as Ectopic AC!H syndrome. 3ung tumors cause over 8> of these cases. Men are affected 4 times more fre$uently than 'omen. !he most common forms of AC!H6 producing tumors are oat cell& or small cell lung cancer& 'hich accounts for a#out ;8 of all lung cancer cases& and carcinoid tumors. (ther less common types of tumors that can produce AC!H are thymomas& pancreatic islet cell tumors& and medullary carcinomas of the thyroid. Cushing:s syndrome 'or% up sho's the results as sho'n in Choice D. Choice A is seen in pituitary adenoma 'hile Choice B is seen in Adrenal neoplasia. Choice C is a distracter 'hile Choice E is normal. ,ince& it is an ectopic AC!H syndrome& AC!H and cortisol 'ill #e elevated. Because the amount of AC!H is very high& itis difficult to suppress even 'ith high dose de-amethasone.
Educational (#)ective* 1atients 'ith ectopic producation of AC!H have very high AC!H levels and their cortisol level is not suppressed 'ith high dose de-amethasone suppression test.
26
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Q NO 23: T, %!&"%,'& o$ &y&'olc loo# 0"&&" 3" o'!,# $"o% ! 0!',' , ' ICU &, !, ,'"!-!"'"!l c!,,l! o+" &+"!l o"&/ T %!.%!l +!l "co"## & 12: %%4 !,# ' %,%!l +!l & 1:: %%4/ I$ ' ,.' %!&"%,' &o3& ' +!l o$ 27: %%4 3c o$ ' $ollo3, & %o&' lkly 'o !00, A. B. C. D. E.
!he !he !he !he !he
mean 'ould increase significantly median 'ould increase significantly mode 'ould increase significantly standard deviation 'ould not change range 'ould not change
Explanation: An outlier is defined as an e-treme and unusual value o#served in a dataset. It may #e the result of a recording error. a measurement error& or a natural phenomenon. An outlier can affect the measures of central tendency& as 'ell as the measures of dispersion. For e-ample& the mean is e-tremely sensitive to outliers and easily shifts to'ard them. In this case& the value of ;G> mmHg is the outlier. /Choice B0 !he median is much more resistant to outliers& #ecause itis located in the middle of the dataset 'here the o#servations usually do not differ much from each other. /Choice C0 !he mode is not affected #y outliers& #ecause they do not change the most fre$uent value o#served. /Choice D0 !he standard deviation is sensitive to outliers& #ecause it is the measure of dispersion 'ithin the dataset& and outliers significantly increase the dispersion. /Choice E0 !he range is e$ual to the ma-imal value minus the minimal value9 therefore& it 'ould definitely change.
Educational (#)ective* An outlier is defined as an e-treme and unusual o#served in a dataset. !he mean is very sensitive to outliers and easily shifts to'ard them. !he median and mode are more resistant to outliers.
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Q NO 24: A 67-y!"-ol# %!l 0"&,'& 'o yo 3' co%0l!,'& o$ ! co +&!l c!,& 3' lo&& !,# 0!, , & "' !"%/ 4 &!y& '!' !& ,o' , $l, 3ll $o" ' 0!&' 2 %o,'&/ 4 & ! &%ok" !,# #!'c/ 4 #,& !,y #" !ll"&/ E.!%,!'o, & ,"%!"k!l/ EC "+!l& ,o"%!l &,& "y'%/ T MRI & &o3, lo3/ W!' & ' %o&' lkly 0!'oloy "&0o,&l $o" ' ,#+#!l& &y%0'o%&
A. B. C. D. E.
Aspergilloma Carcinoid 1ancoast tumor 1neumonia 3ung a#scess
Explanation: !he patient has all the presentations of a malignancy 'ith pain in his right arm. !he MRI sho's a mass in the ape- of the lung. !his is classic #ra 1ancoast tumor. (ther findings may #e the presence of Homer:s syndrome /miosis& anhydrosis and ptosis0. 1ancoast tumors usually gro' in the ape- of the lung /superior sulcus0 and tend to invade the upper chest 'all& ri#s& sympathetic chain and lo'er #rachial ple-us. hen the tumor invades the lo'er #rachial ple-us& it can cause severe pain in the arm along the ulnar nerve. 1reoperative radiation is administered #efore resection of this tumor. 1ancoast tumors may#e of any histology #ut the ma)ority are either s$uamous cell or adenocarcinomas /Choice C0. /Choice A0 Aspergilloma can gro' in the ape- of the lung #ut does not cause arm pain. !he patent may present 'ith hemoptysis& fever& 'eight loss and a chronic cough. !he mass is usually mo#ile and moves 'ith position. !he diagnosis is made #y finding of hyphae in the specimen. !he occasional aspergilloma can spontaneously regress. /Choice B0 Carcinoid tumors usually do not gro' in the lung ape-. !hese tumors are usually centrally located and easily visi#le 'ith a #ronchoscope. !hey may present 'ith a cough and recurrent hemoptysis. !he tumors are slo' gro'ing and have the #est prognosis of all lung cancers. Carcinoid syndrome is a rare presentation. /Choice D0 1neumonia presents as a consolidation #ut does not cause arm pain. !he patient 'ith a large pneumonia can present 'ith cough& copious secretions& fever& elevated BC& and 'eight loss. Diagnosis can
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#e made #y gram stain of sputum specimens. An untreated pneumonia can lead to a parapneumonic effusion and empyema. /Choice E0 3ung a#scess can present as a#ove #ut the patient is usually sic% and ill. Fevers& chills& oral secretions& 'eight loss& chest pain and elevated BC are common findings. An air fluid level is diagnostic. Arm pain does not occur 'ith lung a#scess. Diagnosis is made #y clinical presentation& radiological features and cultures of oral secretions. !reatment is prolonged anti#iotic therapy and surgical drainage. Educational (#)ective* In a smo%er 'ith arm pain& cough and 'eight loss& a mass in the lung ape- is a 1ancoast tumor until other'ise proven.
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Q NO 25: A 6:-y!"-ol# %!l $!"%" 0"&,'& 'o ' o$$c $o" ' +!l!'o, o$ ! &l'ly 0!,$l lc" o, ' 'o0 o$ & lo3" l0/ T lc" !& ,o' !l# &,c $"&' ,o'c# ' '" %o,'& !o/ 4 !& !l3!y& , !l'y !,# #,& !,y &.!l !c'+'y #", ' 0!&' y!"/ 4 & !$"l/ Py&c!l .!%,!'o, &o3& ! >. %% 0!"'!lly ,c"&'# lc" , ' +"%lo, o, ,!" ' %o&' l, (%coc'!,o& ,c'o,) o$ ' lo3" l0 &""o,## y ! 6. 12%% !"! o$ ,#"!'o,/ T" !" ,o 0!l0!l &%,'!l o" &%!,#l!" ly%0 ,o#&/ T "%!,#" o$ ' 0y&c!l .!%,!'o, & ,"%!"k!l/ Co%0l' loo# co,' !,# #$$",'!l !" ,o"%!l/ Bo0&y o$ ' lc" 3ll %o&' lkly 'o &o39
A.
Invasive clusters of spindle cells surrounded #y palisaded #asal cells B. ranulomatous inflammation C. Invasive cords of s$uamous cells 'ith %eratin pearls D. ,hallo' fi#rin6coated ulceration 'ith an underlying mononuclear infiltrate E. iant cells in a !+anc% preparation Explanation: iven the nature of this patient:s ulcer/i.e.& solitary& has not healed over three months& and located in the %eratini+ed epithelium of the vermilion +one of the lo'er lip0the initial differential diagnosis is #road. !he underlying cause may #e a malignant& chronic infectious& or chronic autoimmune process. "evertheless& the most li%ely diagnosis of this patient is s$uamous cell carcinoma& 'hich is characteri+ed #y invasive cords of s$uamous cells 'ith %eratin pearls. !he location of the ulcer and history of occupational sun e-posure ma%e s$uamous cell carcinoma the leading diagnosis& as does the epidemiological fact that the ma)ority of lip cancers are 'ell6differentiated s$uamous cell c arc i no ma s. /Choice A0 Basal cell carcinomas are histologically characteri+ed #y invasive clusters of spindle cells surrounded #y palisaded #asal cells. Basal cell cancer is rarely found on the lips. In sporadic instances& it has #een reported onaround the upper lip& #ut hardly ever on the lo'er lip. /Choice B0 ranulomas could #e found if the ulcer 'as a gumma of tertiary syphilis or a local tu#erculosis infection9 ho'ever& these are unli%ely possi#ilities. A gumma of #enign tertiary syphilis is a remote possi#ility& #ut this is very rare in the anti#iotic era. Myco#acterium tu#erculosis can produce oral ulcers inoculated #y sputum from the lungs9 ho'ever& a patient 'ith sufficiently active pulmonary tu#erculosis to produce infective sputum 'ould li%ely have additional symptoms such as fever& night s'eats& cough& andor hemoptysis. A fungal cause is also impro#a#le since the patient is neither de#ilitated nor o#viously immunocompromised. 2enereal disease ulcerations 'ould have arisen 'ithin a fe' months of the patient:s last se-ual encounter. Cyclic neutropenia is ruled out #y a normal CBC. /Choice D0 Aphthous ulcers are descri#ed as shallo'& fi#rin6coated ulcerations 'ith underlying mononuclear infiltrates. Aphthae /can%er sores0 are recurrent& self6limiting ulcerations of indeterminate /possi#ly autoimmune0 etiology. !hese arise in the mucosa of the oral cavity& #ut not in surfaces covered #y %eratini+ed stratified s$uamous
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epithelium. !hese are not found in the vermilion +one of the lips or on the gingiva. /Choice E0 Conceiva#le viral causes are typically characteri+ed #y multiple andor simultaneous lesions or signs in other areas of the #ody. An e-ception is a recurrent herpetic cold sore /i.e.& la#ial or peri6oral0'hich could arise in the same location as this patient:s ulcer& #ut 'ould #e e-pected to heal 'ithin t'o 'ee%s. A !+anc% preparation is used to demonstrate the characteristic giant cells /cell fusions0 found in the #lister fluid of herpetic infections. Educational (#)ective* !he most li%ely diagnosis of an asymptomatic /i.e.& lesion6free0& immunocompetent adult patient 'ith a non6healing& isolated ulcer in the vermilion +one of the lo'er lip and a significant history of sun e-posure is s$uamous cell c arc i no ma.
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Q NO 26: A 8=6year6old nurse 'ith node6positive metastatic #reast cancer comes to the office for her monthly follo'6up visit. !he tumor is estrogen receptor /ER0 and progesterone receptor /1R0 positive& and her 'hole #ody #one scan is positive for metastatic disease. ,he is #eing treated 'ith systemic chemotherapy and hormonal therapy /!amo-ifen0. ,he feels 'ea% 'ith vague muscle )oint& and #one pains. 1hysical e-amination reveals a hard& 'ell6defined dominant mass in the left #reast. Mucus mem#ranes are moist. 3a#oratory studies sho' the follo'ing results. ,odium 4 mE$d3 Bicar#onate ;G mE$d3 Calcium << .4 mgd3 B@" <=mgd3 Creatinine >.= mgd3 lucose
A. B. C. D. E.
Corticosteroid therapy Loledronic acid therapy Intravenous normal saline Furosemide therapy Intravenous mithramycin
Explanation: !he patient:s complaints are due to metastatic disease and resultant hypercalcemia. In patients 'ith malignancy& hypercalcemia is due to the increased #one resorption and the release of calcium from the #one. !he pathology involves osteolytic metastases 'ith local release of cyto%ines and tumor secretion of parathyroid hormone6related protein /1!Hr10. Bisphosphonates are the drugs of choice for mild to moderate hypercalcemia. !hese drugs are relatively nonto-ic and more potent than intravenous saline. In addition& there is increasing evidence that #isphosphonates may prevent s%eletal complications /reduce #one pain& fracture ris%0& and perhaps improve survival in patients 'ith multiple myeloma or #reast cancer. According to the clinical practice guidelines pu#lished #y the American ,ociety of Clinical (ncology /A,C(0& intravenous Loledronic acid /LometaAN0 is recommended in all 'omen 'ho have metastatic #reast cancer and radiographic lytic #one disease& and are receiving either hormone therapy or chemotherapy. /Choice A0 Corticosteroids are used in patients 'ith hypercalcemia due to e-tra renal production of <.;8 dihydro-y vitamin D /calcitriol0 such as sarcoidosis. /Choices C and D0 I2 fluids and furosemide are used in the treatment of hypercalcemic crisis. /Choice E0 Although I2 mithramycin is highly effective& it is rarely used #ecause of its to-icity.
Educational (#)ective* Bisphosphonates are the drugs of choice for mild to moderate hypercalcemia due to malignancy.
32
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Q NO 27: A ?-y!"-ol# 3o%!, & "o' 'o ' %",cy #0!"'%,' # 'o ! &&0c'# c""o+!&cl!" !cc#,' o, " "' &#/ S co%0l!,& o$ #$$& 0!"&'&!& !,# ',l, , " "' !,#/ S ## ,o' lo& co,&co&,&&/ T 0y&c!l .!%,!'o, "+!l& ,o"%!l &0c &y%%'"c #0 ',#o, "$l.& (2;7 o, o' 00" .'"%'& 2;7 o' 0!'ll!" "$l.& !,# :;7 o' Acll& "$l.&) ! col# "' !,# !,# ,#'c'!l !"'"!l "!#!l 0l&/ T,l !,# P!l,& &,& !" ,!'+/ T "&' o$ ' .!%,!'o, & ,o"%!l/ W!' & ' %o&' !00"o0"!' ,.' &'0 , ' %!,!%,' o$ '& 0!',' A. B. C. D. E.
C! scan of the #rain 'ithout contrast MRI scan of the #rain 'ith diffusion images Doppler of the carotid arteries ,chedule for EMI and nerve conduction studies Immediate vascular surgery consultation for intervention
Explanation: !his patient:s presentation is typical for an em#olus in her right upper e-tremity arterial #ed& specifically the radial artery. 1atients characteristically have a normal neurological e-am 'ith persistent signs of ongoing ischemia /e. g.& paresthesias& change in temperature& and non6detecta#le radial arterial pulsations0. Immediate anticoagulation 'ith heparin and surgical intervention /i.e.& em#olectomy0 are crucial& #ecause this condition can lead to tissue death and amputation if not effectively treated 'ithin hours. /Choices A and B0 !he patient:s normal neurology e-amination ma%es the diagnosis of stro%e unli%ely.
Educational (#)ective* Immediate anti coagulation 'ith heparin and surgical intervention /i.e.& em#olectomy0 are crucial to prevent tissue death in a patient 'ith ongoing ischemia of the lim#.
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USMLE WORLD STEP 2 CK 1*
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Q NO 28: A 6:-y!"-ol# 3' %!l 0"&,'& 'o ' ER 3' &##, o,&' o$ c&' 0!, ,!&! +o%', !,# #!0o"&&/ 4 #&c"& '& c&' 0!, !& ! &, &,&!'o, ' &'!"'# 2 o"& !o !' "&' "!#!'& 'o !3 !,# & 0!"'!lly "l+# y &l,!l ,'"olyc",/ 4 !& ! &'o"y o$ >: 0!ck;y!" o$ c!"'' &%ok,/ 4 & ! k,o3, y0"',&+ $o" ' 0!&' 1: y!"& !,# &$$"# ! %o""!c &'"ok 6 %o,'& !o/ 4& %#c!'o,& ,cl# !&0", !',olol !,# y#"oclo"o'!#/ O, .!%,!'o, PR9 6;%,< BP9 1>?;? %%4< RR9 1>;%,< T%0"!'"9 >/>:(??@)/ O, !&cl'!'o, l,& !" cl!" !,# !"' &o,#& !" ,o"%!l/ C&' .-"!y & ,o"%!l/ EK &o3& ST &%,' l+!'o, o$ 2%% , l!#& > 'o 6/ T& ST c!,& 0"&&' !$'" &l,!l ,'"olyc",/ Wc o$ ' $ollo3, &'0& & ' %o&' !00"o0"!' "!"#, ' %!,!%,' o$ '& 0!',' A. B. C. D. E.
I2 tissue plasminogen activator& I2 heparin& and aspirin I2 tissue plasminogen activator and aspirin I2 heparin& I2 nitroglycerin& and aspirin I2 amiodarone and I2 magnesium Immediate coronary angiography and 1!CA
Explanation: E-planation* !he a#ove patient is li%ely to #enefit from throm#olytic therapy& #ut he has a history of a relatively recent hemorrhagic stro%e /less than < year ago0. !hrom#olytic therapy 'ould put him at a tremendous ris% for intracranial #leeding and is therefore contraindicated. In such circumstances& immediate coronary angiography and 1ICA or stent is the procedure of choice. !hrom#olytic therapy is indicated 'hen the chest pain is suggestive of Ml and there is J,!: segment elevation greater than < mm in t'o contiguous leads after su#lingual nitroglycerin administration to rule out coronary vasospasm. Another indication for throm#olytic therapy is a ne' or presuma#ly ne' left #undle #ranch #loc%. !hrom#olytic therapy is not indicated for an MI 'ith J,!: segment depression and it is also not indicated for unsta#le angina. In these settings& no proven #enefit has #een sho'n for throm#olytic therapy. !hrom#olytic therapy can #e given 'hen J,!: depression sho's a posterior MI& especially in the setting of an inferior 'all MI. A#solute contraindications to throm#olytic therapy include* active internal #leeding* history of hemorrhagic stro%e anytime& or an ischemic stro%e 'ithin past year* %no'n intracranial neoplasm* current systolic B1 greater than <=> or diastolic B1 greater than <<>* or suspected aortic dissection. !hrom#olytic therapy 'ith tissue plasminogen activator re$uires co6 administration of heparin and aspirin for greater #enefit. !issue plasminogen activator is slightly more effective than strepto%inase #ut it has a slightly more ris% of intracranial #leeding. For strepto%inase& co6administration of heparin is not re$uired. !reatment 'ith I2 heparin& aspirin& and I2 nitroglycerin is indicated in cases of unsta#le angina and non6O 'ave infarcts. In those cases& throm#olytic therapy has not #een sho'n to #e associated 'ith a proven #enefit. I2 amiodarone and I2 magnesium are not useful in the setting of Ml unless arrhythmias or lo' serum magnesium levels complicate it. Educational (#)ective* 34
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Manage a patient 'ith J,I: segment elevation MI 'ith immediate angiography and 1ICA 'hen throm#olytic are contraindicated. Even if the patient has no contraindications for throm#olytic therapy and a catheteri+ation la#oratory is availa#le in the hospital& or 'ithin 4> min of the hospital& 1ICA 'ith stent placement has #een sho'n to have #etter outcomes than throm#olytic therapy in acute J,!: elevation MI.
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Q NO 29: A 8>6year6old 'oman comes to the emergency department 'ith a very painful left leg. !he pro#lem started one day ago 'hen she developed pain in the leg. !here is no history of trauma to the calf. ,he has hypertension and dia#etes9 #oth 'ere diagnosed 4 years ago. !here is no past history of arthritis. ,he is currently ta%ing captopril& glipi+ide& and 2itamin E preparation. (n physical e-amination& her temperature is 4=. C /<>4 F09 1ulse is <>5min& B.1 <4>=>& and R.R ;>min. Her left calf is s'ollen& erythematous& and e-tremely tender to touch. !here is no overlying crepitus and #ullae. !he area of involvement of the calf is a#out 5P4 cm. !here are linear strea%s of erythema along the thigh. !he toe 'e#s are fissured and macerated. !he patient tells that itching and stinging in interdigital 'e#s has #een $uite distur#ing for her. 3a#s revealed* Hemoglo#in <; gmd3 E,R 8> mmhr BC <;&>>>cmm 1latelet ;8>&>>>cmm hat is the most pro#a#le diagnosis
A. B. C. D. E. F. .
Cellulitis Deep venous throm#osis ,clerosing panniculitis Ruptured #a%er:s cyst Erysipelas Erysipeloid "ecroti+ing fascitis
Explanation: !his patient has cellulitis& 'hich is a diffuse infection of deep layers of s%in. 1resence of fever& inflammatory signs& no crepitus or #ullae and signs of overlying s%in necrosis all suggest that the patient has cellulitis. !his patient also had toe 'e# tinea pedis& 'hich is one of the most common portals of entry for the microorganisms& causing cellulitis. Cellulitis of calf is difficult to differentiate from deep venous throm#osis. Ho'ever presence of high6grade fever& lymphangitis& a#sence of any ris% factor such as orthopedic surgery& or prolonged immo#ili+ation ma%e deep venous throm#osis unli%ely. Ba%er:s cyst is a complication of rheumatoid arthritis. !his patient has no history of arthritis. "ecroti+ing fasciitis is a deep6seated cellulitis. It should #e suspected in a patient 'ho has evidence of overlying s%in necrosis& #ullae& 'ith anesthesia due to destruction of nerves& crepitus due to gas producing organism& and fever. ,clerosing panniculitis is acute tender lesion over the medial malleolus. It usually occurs in a patient 'ith venous stasis of lo'er lim#. Erysipelas is a superficial cellulitis. It usually affects chee%. !he area involved #ecome erythematous& tender& sharply demarcated and 'ith vesicles or #ullae. !here is no element of lymphangitis. Fever is usually present. Erysipeloid is an edematous& purplish pla$ue 'ith central clearing. It is caused #y Erysipelothri- insidiosa. It usually occurs on the hands of fishermen and meat handlers. It is not very painful li%e cellulitis. Fever is not present. Educational (#)ective* 1ainful leg in a lady is fre$uently tested in @,M3E e-ams. no' ho' to deal 'ith various possi#le scenarios.
36
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 30: A 65-y!"-ol# %!l 3' o.y,-#0,#,' c"o,c o&'"c'+ 0l%o,!"y #&!& c"o,c !'"!l $"ll!'o, !,# #0"&&o, co%& ,'o ' E%",cy Roo% 3' &y%0'o%& o$ ,c"!&# #y&0,! !,# 3o"&,, co 0!''",/ 4& "c,' &'o"y !# , &,$c!,' $o" ! "!#!l 3o"&,, o$ & !&l, l, #&!& o+" ' 0!&' %o,' 3c !# , '"!'# y & o'0!',' #oc'o" 3' ,c"!&# $",cy o$ ,!l# '!-!o,&' !,# !'"o%yc,/ T& %o",, !# ! &+" &o"',&& o$ "!' '!' 3!& ,"&0o,&+ 'o &'!ck#J o% ,l" '"!'%,'&/ T ER 0y&c!, ,o'& '!' ' 0!',' & , %o#"!' &+" "&0"!'o"y #&'"&&/ 4& '%0"!'" & >/2 C (?? @) loo# 0"&&" & 15:;?: %%4 0l& & 11:;%, !,# "&0"!'o,& !" 2=;%,/ Acc&&o"y %&cl & 3!& ,o'#/ L, .!% &o3& #$$& "o,c !,# 3,/ A 0l& o.%'"y "+!l# !, o.y, &!'"!'o, o$ =: o, "oo% !"/ 4& c&' .-"!y &o3# ,o ,3 ,$l'"!'&/ 4& WBC co,' & :::;c%% 3' ,o"%!l #$$",'!l/ T ER 0y&c!, !# +, ,l!'o, !,# ' 0!',' & o, 5-l'"& o$ o.y,/ Wc o$ ' $ollo3, &ol# !l&o co,&#"# , '& 0!',' A. B. C. D. E.
atiflo-acin Methylprednisolone "6acetylcysteine Clarithromycin Aminophylline
Explanation: !his patient has a history of chronic o#structive pulmonary disease /C(1D0. His current symptoms are manifestation of an acute e-acer#ation of his underlying disease. !he acute episodes are typically managed 'ith ipratropium and al#uterol ne#uli+ation and systemic steroids. !he most commonly used parenteral steroid is methylprednisolone /Choice B0. "6acetylcysteine is a mucolytic agent& 'hich is no longer used in e-acer#ation of C(1D& as they are even implicated in 'orsening #ronchospasm /Choice C0. !here is some role of anti#iotics& li%e gatiflo-acin and clarithromycin& in the management of an acute episode of dyspnea in a patient 'ith severe o-ygen dependent C(1D* ho'ever& this patient has already #een treated 'ith anti#iotics& has no fever BC count is normal& and there is no infiltrate on chest -6ray. ,o& due to the previous facts& having pneumonia or a #acterial infection is unli%ely /Choices A and D0. Aminophylline is proven to #e inferior to a com#ination of #ronchodilator and corticosteroids for the treatment of acute e-acer#ation of C(1D /Choice E0.
Educational (#)ective* Acute e-acer#ation of C(1D is treated 'ith a com#ination of inhaledne#uli+ed #ronchodilators and systemic steroids.
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37
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 31: A 55-y!"-ol# A&!, %!, 3' %'"!l &',o&& &co,#!"y 'o "%!'c !"' #&!& ,#"o& #,'!l &""y $o" c!"&/ Po&'o0"!'+ly #o& 3ll !,# & #&c!"# o%/ T3o 3k& l!'" 0"&,'& 3' $+" cll& $!' !,# $l& &ck/J @o" o' o$ $o" loo# cl'" o''l& !" 0o&'+ $o" "!%-0o&'+ cocc/ A, coc!"#o"!% & 0"$o"%# !,# &o3& %'"!l +!l+ +'!'o,&/ Wc o$ ' $ollo3, & ' %o&' lkly c!&!'+ o"!,&% o$ '& 0!','& co,#'o, A. B. C. D. E.
roup B streptococci ,treptococcus mutans ,treptococci #ovis ,taphylococcus epidermis Enterococci
Explanation: !his patient has su#acute infective endocarditis /IE0 of the mitral valve secondary to dental surgery. His pre6e-isting mitral stenosis is a predisposing factor for infective endocarditis& and #acteremia caused #y dental surgery further increases such ris%. 2iridans group streptococci are the most li%ely cause of endocarditis in native valves follo'ing dental procedures. Four mem#ers of the viridans group cause IE* ,treptococcus mitis& ,. sanguis& ,. mutans& and ,. salivarius. ,. mutans also causes dental caries. /Choice A0 Ris% factors for roup B streptococcal endocarditis include dia#etes mellitus& carcinoma& alcoholism& hepatic failure& elective a#ortion& and intravenous drug use. /Choice C0 ,. #ovis is a normal inha#itant of the I tract& and ,. #ovis #acteremia is associated 'ith colon cancer. Colonoscopy should #e performed 'hen this organism is isolated from #lood cultures. /Choice D0 ,. epidermidis is an important cause of prosthetic valve endocarditis. It is also seen in infants 'ith IE secondary to um#ilical venous catheter infection in neonatal intensive care units. /Choice E0 Enterococci are normal inha#itants of the gastrointestinal tract and also occasionally coloni+e the anterior urethra. Enterococcal endocarditis generally affects older men after genitourinary manipulation or younger 'omen after o#stetric procedures.
Educational (#)ective* 2iridans group streptococci /most commonly ,. mutans0 are the most common cause of endocarditis follo'ing dental procedures.
38
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 32: A 6:-y!"-ol# 3' %!, co%& ,'o ' E%",cy Roo% 3' ,',&+ "'"o&'",!l 0!, '!' !, ', %,'& !o/ 4 !& ,+" !# &c 0!, $o"/ 4& 0!&' %#c!l &'o"y & &,$c!,' $o" #!'& %ll'& 'y0 2 co,'"oll# 3' #'/ 4& loo# 0"&&" & 15:;?5 %%4 !,# 4R & =:;%,/ 8o + % o, c3!l '!l' o$ !&0", !,# '3o &l,!l '!l'& o$ ,'"olyc", 3' ! 5-%,' ,'"+!l/ A$'" ' &co,# '!l' o$ ,'"olyc", ' 0!, & "!'ly "l+#/ W!' & ' %o&' %0o"'!,' %c!,&% "&0o,&l $o" 0!, "l$ , '& 0!',' A. B. C. D. E.
Increase in coronary #lood flo' Increased cardiac contractility Dilation of resistance vessels Dilation of capacitance vessels Change in the activity of #aroreceptors
Explanation: !he primary mechanism responsi#le for the effect of nitroglycerin in patients 'ith anginal pain is dilation of veins /capacitance vessels0. Increased venous capacitance and venous pooling of the #lood lead to significant decrease in ventricular preload and decrease in heart si+e. As the result of these changes& o-ygen re$uirement of the heart greatly reduces. "itroglycerin also causes arterial dilation /Choice C0 and& therefore& decreases ventricular after load& #ut this effect has less significance in relieving anginal pain. It is unclear 'hether nitroglycerin significantly increases coronary #lood flo' in patients 'ith o#structive coronary heart disease /Choice A0& although it does so in healthy su#)ects. ,econdary effects provo%ed #y nitroglycerin li%e increased heart contractility /Choice B0 and refle- tachycardia are due to change in the activity of #aroreceptors /Choice E0 in response to the decrease in #lood pressure. !hese effects increase myocardial o-ygen demand.
Educational (#)ective* !he main mechanism responsi#le for pain relief in patients 'ith anginal pain treated 'ith nitroglycerin is dilation of veins and decrease in ventricular preload.
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39
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 33: A 2-y!"-ol# %!l 0"&,'& 3' ! '3o-#!y &'o"y o$ ,',& 0!, , & "' !" !lo, 3' !" #&c!"/ T 0!, & &o &+" '!' & ,!l 'o &l0/ I' "!#!'& 'o & '%0o"o%!,#l!" o,' !,# & !"!+!'# y c3,/ 4& #&!& !& 3o"&,# #&0' ' & o$ 'o0c!l !,'o'c&/ 4 '!k& %'$o"%, !,# ,!l!0"l/ O, 0y&c!l .!%,!'o, "!,l!'o, '&& & ,o'# , ' lo3" 0!"' o$ & .'",!l !#'o"y c!,!l/ C"!,!l ,"+& !" ,'!c'/ O"o0!"y,. & cl!" 3'o' .#!'/ Wc o$ ' $ollo3, & ' %o&' lkly c!&!'+ o"!,&% o$ '& 0!','& !" co,#'o, A. B. C. D. E. F. . H. I. .
1seudomonas aeruginosa ,taphylococcus aureus Bacteroides species 1eptostreptococcus species Aspergillus fumigatus 1roteus mira#ilis le#siella o-ytoca ,treptococus pneumoniae Hemophilus influen+ae Actinomyces israelii
Explanation: !he typical symptoms of malignant otitis e-terna are ear discharge and severe ear pain. !he pain often radiates to the temporomandi#ular )oint& and conse$uently causes pain that is e-acer#ated #y che'ing. orsening of the disease despite the use of topical anti#iotics is an important indicator of the condition:s malignant nature. E-amination sho's the presence of granulation tissue in the e-ternal auditory meatus. Dia#etes mellitus and other immunosuppressive conditions are important ris% factors. !he most fre$uent causative organism is 1seudomonas aeruginosa& 'hich is implicated in more than K8 of cases. /Choices B and E0 Aspergillus fumigatus and ,taphylococcus aureus are very rare causes of malignant otitis e-terna. /Choices C and D0 Anaero#es /e.g.& Bacteroides& 1eptostreptococcus0 are infre$uent causes of simple otitis e-terna.
Educational (#)ective* ,uspect malignant otitis e-terna in any dia#etic patient 'ith severe ear pain& otorrhea& and evidence of granulation tissue in the ear canal. 1seudomonas aeruginosa is the most fre$uent cause of malignant otitis e-terna.
40
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 34: A 65-y!"-ol# $%!l & co%0l!,, o$ &, ! &##, "&' o$ $l!&, l'& !,# l""# +&o, , " l$' y/ T& &y%0'o%& &'!"'# '& %o",,/ S ,o3 && &%!ll &0o'& , " $l# o$ +&o,/ S $l' lk ! c"'!, c!% #o3,J o+" " y/ S !# ! &cc&&$l c!'!"!c' .'"!c'o, , " l$' y 7 %o,'& !o/ 4" +'!l &,& !" &'!l/ E.!%,!'o, &o3& ! &l& l$' 00l/ O0'!l%o&co0y "+!l& "',!l '!"& !,# ! "!y&-!00!", "',!/ W!' & ' %o&' 0"o!l #!,o&& A. B. C. D. E.
Choroidal rupture Retinal detachment Central retinal artery occlusion 1roliferative dia#etic retinopathy E-udative macular degeneration
Explanation: Retinal detachment refers to the separation of the layers of the retina. It usually occurs in people aged G>6> years. 1atients complain of photopsia /flashes of light0 and floaters /spots in the visual field.0. !he most classic description is that of a curtain coming do'n over my eyes. @sually& the inciting event occurs months #efore retinal detachment. Myopia or trauma can cause retinal #rea%s& through 'hich fluid seeps in and separates the retinal layers. In this patient& ocular trauma most li%ely occurred due to her cataract surgery. (phthalmoscopic e-amination reveals a grey& elevated retina. 3aser therapy and cryotherapy are done to create permanent adhesions #et'een the neurosensory retina& retinal pigment epithelium& and choroid. /Choice A0 Choroidal rupture occurs due to #lunt ocular trauma. E-amination reveals central scotoma& retinal edema. hemorrhagic detachment of the macula& su#retinal hemorrhage& and crescent6shaped strea% concentric to the optic nerve. !he usual complaint is #lurred vision follo'ing #lunt trauma. /Choice C0 Central retinal artery occlusion /CRA(0 is also characteri+ed #y a sudden painless loss of vision in one eye& #ut its funduscopic findings differ. (phthalmoscopy of patients 'ith CRA( reveals pallor of the optic disc& cherry red fovea& and #o-car segmentation of #lood in the retinal veins. /Choice D0 1roliferative dia#etic retinopathy in the initial stage is asymptomatic. 1atients may later complain of decreased visual acuity. "eovasculari+ation is the hallmar% of proliferative dia#etic retinopathy. !he other findings are vitreous hemorrhage and macular edema. !hese changes may lead to retinal detachment. /Choice E0 E-udative macular degeneration typically presents as painless& progressive #lurring of central vision& 'hich can #e acute or insidious. It occurs #ilaterally. !esting reveals central scotoma. (phthalmoscopy reveals gro'th of a#normal vessels in the retinal space. ,udden visual loss may occur if it is complicated #y retinal detachment.
Educational (#)ective* Retinal detachment usually presents 'ith a sudden onset of photopsia and floaters. !he most classic description is that of a curtain coming do'n over my eyes.
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41
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 35: A 2-y!"-ol# 3o%!, 0"&,'& 'o ' o$$c # 'o ! &,$c!,' !%o,' o$ !" o, " ck& c, !,# 00" l0&/ T& &y%0'o% #+lo0# o+" ' 0!&' '3o %o,'&/ 4" l!&' %,&'"!l 0"o# 3!& 12 3k& !o ' & ## ,o' &k %#c!l l0 c!& " o% 0",!,cy '&' 3!& ,!'+/ 4" %#c!l &'o"y & ,"%!"k!l/ S #,& '!k, !,y %#c!'o,& o'" '!, o"!l co,'"!c0'+ 0ll&/ Py&c!l .!%,!'o, "+!l& !c, o, ' $o"!# !,# ck&< '" & '"%,!l !" o, ' 00" l0 ck& c, 00" c&' !,# lo3" !#o%,/ E.!%,!'o, o$ ' ,'!l& &o3& cl'o"o%!ly/ T !#o%,!l .!% & ,o"%!l< ' '"& & ,o"%!l , &/ Ul'"!&o,# "+!l& ! ,o"%!l '"& !,# o+!"& ' '" & ! l$' !#",!l %!&&/ Wc o$ ' $ollo3, & %o&' lkly 'o ,c"!&# , '& 0!','& &"% A. B. C. D. E. F.
3uteini+ing hormone /3H0 Adrenocorticotropic hormone /AC!H0 !estosterone Androstenedione Dihydrotestosterone Dehydroepiandrosterone6sulfate
Explanation: omen produce androgens& such as androstenedione /A,0& dehydroepiandrosterone /DHEA0& testosterone /!0 and dehydroepiandrosterone sulfate /DHEA6,0. A, DHEA and !are produced #y the ovaries and adrenals& 'hereas DHEA6, is predominantly produced in the adrenal glands only. A,& DHEA and DHEA6, are not true androgens #ecause they do not interact 'ith the androgen receptor. !hey can #e converted to testosterone& and overproduction of these hormones can lead to clinical features of androgen e-cess /as in this patient0. /Choice B0 An increase in AC!H levels in patients 'ith hirsutism are seen in patients 'ith ectopic or pituitary6 dependent Cushing:s disease. AC!H increases the production of cortisol& as 'ell as androgens from the adrenal glands* ho'ever& the adrenal glands sho' diffuse hyperplasia rather than a discrete adenoma. /Choices C and D0 !estosterone and androstenedione levels may #e elevated in #oth adrenal and ovarian tumors. /Choice E0 Dihydrotestosterone is the product of the testosterone conversion in peripheral tissues #y 86alpha6 reductase. It is a potent androgen and interacts 'ith the testosterone receptors. Increased dihydrotestosterone levels are not specific for androgen6producing adrenal tumors.
Educational (#)ective* Elevated serum DHEA6, levels are specifically seen in patients 'ith androgen6producing adrenal tumors.
42
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 36: A >2-y!"-ol# %!, 0"&,'& $o" ! "o', !l' .!%,!'o, c!& '& ! ""%,' $o" & ,3 o/ 4 !& ,o co%0l!,'& !' '& '%/ 4 &'!'& '!' !& ,o &'o"y o$ %#c!l 0"ol%& !,# '!k& ,o %#c!'o,&/ 4 !#%'& 'o $",' ,'"!+,o& #" !& !,# ,'"!,!&!l coc!, !&/ Py&c!l .!%,!'o, & ,"%!"k!l 3' ,o +#,c o$ 0!'o%!ly o" c'"&/ S"oloc '&', $o" 0!''& C & 0"$o"%#/ Wc o$ ' $ollo3, & ' &,l %o&' &,&'+ &"oloc!l %!"k" &# 'o &c", $o" 4C ,$c'o, A. B. C. D. E.
,erum aminotransferase HC2R"A Anti6HC2 R"A ,erum al%aline phosphatase 3iver #iopsy
Explanation: Although there has #een a recent mar%ed increase in cases of #lood transfusion6related hepatitis C virus /HC20 infection& the ris% of ac$uiring the virus through transfusion 'as recently estimated to #e Q<*8G>.>>>. Intravenous drug a#use continues to account for 8>68 of all ne' cases of HC2 infection. ,ince this patient is an intravenous drug a#user& he is at high ris% for infection 'ith HC2. Intranasal cocaine a#use is also an independent ris% factor for HC2 infection& there#y increasing the li%elihood that this patient 'ill test positive. (ther ris% factors include #ody piercing& hemodialysis& and multiple se-ual partners. As the first mar%er of HC2 infection to appear in the serum& HC2 R"A may #e detected 'ith 1CR 'ithin days to 'ee%s after infection& depending on the si+e of the inoculum. Because this test is the most sensitive serological mar%er for diagnosis of HC2 infection& it is considered the gold standard. HC2 R"A can #e detected #efore elevation of aminotransferases and #efore the appearance of anti6HC2. Moreover& HC2 R"A is detecta#le indefinitely /continuously or intermittently0 in patients 'ith chronic hepatitis C infection. /Choice A0 !he serum aminotransferases are nonspecific mar%ers of hepatic in)ury that #ecome elevated appro-imately 56<; 'ee%s after e-posure to HC2. !hese levels tend to 'a- and 'ane. "ormali+ation of serum A3! concentration in a patient 'ith %no'n HC2 infection does not indicate that the infection has resolved. /Choice C0 Commonly used in the diagnosis of hepatitis C infection& anti6 HC2 anti#odies can #e detected 'ith the E3I,A techni$ue as early as eight 'ee%s after e-posure. Ho'ever& some patients may not #e positive for several months after e-posure or may never test positive. In addition& this mar%er does not distinguish #et'een acute and chronic infections. Anti6HC2 is considered to have moderate sensitivity early in the disease course #ut lo' specificity in patients 'ith elevated gamma glo#ulin levels. If infection is clinically suspected #ut not confirmed #y the presence of anti6HC2& then HC2 R"A levels should #e o#tained. /Choice D0 ,erum al%aline phosphatase is a #etter indicator of #iliary tract pathology than of hepatitis. /Choice E0 3iver #iopsy is nota screening tool for viral hepatitis& as the appropriate serological tests are more sensitive and cost6effective. 3iver #iopsy is typically of considera#le help in determining the etiology of a hepatic mass or infiltrative liver disease& ho'ever. Educational (#)ective* HC2 R"A is the single most sensitive serological mar%er used in screening for HC2 infection.
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43
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 37: A 55-y!"-ol# %!l 0!',' co%& 'o & 0"%!"y c!" 0y&c!, $o" & "o', !l' c!" .!%,!'o,/ 4 & co%0l'ly !&y%0'o%!'c !,# !& ,o', &,$c!,' , & 0!&' %#c!l &'o"y/ 4 !& 1: 0!cky!" &'o"y o$ &%ok, ' #o& ,o' #",k !lcool/ 4& PR9 =:;%,< BP9 15:;=%% 4< T%0"!'"9 >/1 C (?=/= @)/ L!& &o3 %!'oc"'o$7> loo# lco& o$ ?: %;#l &"% c"!',, o$ :/ %;#L &"% N! o$ 17: %E;L !,# &"% K o$ 7 %E;L/ U",!ly&& !,# EK !" ,"%!"k!l/ 4& loo# 0"&&" "!#,& o, &&,' +&'& !" 155;=: %%4 16:;= %%4 !,# 15:;: %%4/ L$-&'yl %o#$c!'o,& $!l 'o co,'"ol & loo# 0"&&"/ Wc o$ ' $ollo3, & ' &' ,'!l 0!"%!coloc!l '"!0y $o" ' co,'"ol o$ & loo# 0"&&" A. B. C. D. E.
!hia+ide diuretics Hydrala+ine ACE inhi#itors Angiotensin receptor #loc%ers Calcium channel #loc%ers
Explanation: E-planation* !his patient is suffering from isolated systolic H!". !he initial drug of choice& for these patients& is a lo'6 dose thia+ide diuretic. 3ong acting dihydropyridine calcium channel #loc%ers are an accepta#le alternative& #ut they are more e-pensive. ACE inhi#itors and angiotensin receptor #loc%ers are not first line agents in the treatment of isolated systolic hypertension 'ithout any other co6mor#idities. Hydrala+ine is not a first line agent in the treatment of hypertension.
Educational (#)ective* !hia+ide diuretics are the initial drugs of choice in people 'ith isolated systolic hypertension.
44
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 38: A 61-y!"-ol# C!c!&!, %!l 0"&,'& 3' 0'o&& #0lo0! !,# l% 3!k,&&/ T& &y%0'o%& 3o"&, , ' +,, !,# 3' ."c& !,# %0"o+ 3' "&'/ 4 !l&o !& $!' 3c & 3o"& , ' +,,/ 4 #,& !,y ',l, o" ,%,&&/ O, .!%,!'o, c!,,o' &&'!, !, 03!"# ! !,# & yl#& ',# 'o #"$' #o3,3!"#/ I,c'o, o$ #"o0o,% ckly "&'o"& 0o3" !,# !llo3& % 'o %!,'!, !, 03!"# !/ Wc o$ ' $ollo3, & ' &' ,'!l '"!'%,' $o" '& 0!',' A. B. C. D. E. F.
!reatment 'ith !reatment 'ith !reatment 'ith !reatment 'ith !reatment 'ith 1lasmapheresis
pyridostigmine edrophonium atropine prednisolone intravenous immunoglo#ulins
Explanation: !here are three treatment options availa#le for the treatment of myasthenia gravis. !hese include anticholinesterases& immunosuppressive agents and thymectomy. Anticholinesterases provide symptomatic #enefit& #ut do not induce remission. Immunosuppressive agents and thymectomy may induce remission. !he choice of treatment depends on the patient:s age and the clinical scenario. (ral anticholinesterase is usually the initial treatment of choice for myasthenia gravis. It produces its useful effect #y increasing the availa#ility of acetylcholine at the neuromuscular )unction& 'here the num#er of acetylcholine receptors is reduced due to acetylcholine receptor anti#odies. 1yridostigmine or neostigmine is used for treatment purposes. ,ide effects include a#dominal cramps& fasciculations and muscular 'ea%ness. /Choice B0 Edrophonium is a short acting anti6cholinesterase& and is used for diagnostic purposes only. /Choice C0 Atropine is an anticholinergic agent that can #e used to prevent muscarinic side effects of anticholinesterase therapy in patients 'ith myasthenia gravis. /Choice D0 Immunosuppressive agents that are used in the treatment of myasthenia gravis include prednisolone& a+athioprine and cyclosporine. Corticosteroids are used in /<0 patients 'ho are over 5> years of age& and /;0 patients 'ho sho' a poor response to anti cholinesterases and have already undergone thymectomy. /Choice F0 1lasmapheresis removes acetylcholine receptor anti#odies from the circulation. It is used in seriously ill patients 'hen other treatments are not effective or contraindicated. Its effect is transient and cannot #e used on a long6 term #asis. (ther indications of plasmapheresis include /<0 sta#ili+ation of the patient #efore thymectomy& and /;0 myasthenia crisis. /Choice E0 Intravenous immunoglo#ulins act #y an un%no'n mechanism& and are used in the same setting as plasmapheresis.
Educational (#)ective* (ral anticholinesterase is usually the initial treatment of choice for myasthenia gravis. All patients should #e evaluated for a thymectomy.
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45
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 39: 8o !" c!ll# y ' o&0c ,"& 'o +!l!' ! 7-y!"-ol# %!, 3o "$&& 'o !'/ 4 !& '"%,!l colo, c!,c" 3c 3!& #!,o&# = %o,'& !o !,# !& %'!&'!&# 'o & l+"/ 4 !& !l"!#y o, '"o c%o'"!0y 3' 5-@lo"o"!cl H o.!l0l!',/ D", ' 0!&' 7 %o,'& & co,#'o, !& o'', .'"%ly 3o"&/ 4 !& lo&' 5Ol& (21/6k) !,# c"",'ly !00!"& 'o'!lly 3!&'#/ A& yo !00"o!c % &!y& I #o,' $l lk !', !,y', !,# I #o,' 3!,' !,y%o" 0"oc#"& ' Ill #",k !,y 0ll '!' c!, %!k % $l ''"/J 4& !#o%, & #&',## 3' 0o&'+ $l# '"ll&/ 4& l+" !& &+"!l 0!l0!l ,o#l&/ W!' & ' &' 0!"%!coloc!l !,' o$ coc $o" '& 0!','& !,o".! A. B. C. D. E.
Megestrol acetate De-amethasone Dimenhydrinate (ndansetron Metoclopramide
Explanation: Anore-ia is a common pro#lem of terminally ill patients. In palliative care& the rule6of6thum# is that it is al'ays #etter to have oral rather than parenteral nutrition. All efforts need to #e made to encourage the patient to eat ade$uate meals /e.g.& giving the patient his preferred meal& presenting the food attractively& giving small and fre$uent meals0. !he ne-t step is pharmacologic. !he drug of choice for cancer6 associated anore-ia is megestrol acetate& 'hich is a synthetic progestin 'ith progestational effects similar to those of progesterone. Itis currently used as an appetite stimulant in patients 'ith advanced malignancies. 1rednisone may #e used in addition to this drug. /Choice B0 De-amethasone is not used for malignancy6associated anore-ia. /Choices C& D and E0 Dimenhydrinate& ondansetron& and metoclopramide are anti6emetics 'hich are usually given to patients 'ho are undergoing chemotherapy.
Educational (#)ective* Megestrol acetate is the drug of choice for cancer6associated anore-ia.
46
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 40: A 6?-y!"-ol# C!c!&!, %!l ,#"o& o0,-!"' &""y $o" CAB !,# !o"'c +!l+ "0l!c%,'/ 4& &""y & ,+,'$l/ 4 & .'!'# !,# #&c!"# 'o ' &'0 #o3, ,' o, 0o&'o0"!'+ #!y 2/ A' ,' ' ,"& &##,ly c!ll& yo c!& ' 0!',' & $l, #"y !,# & 'l %o,'o" & !,o"%!l/ 4& BP & :;>:%% 4 !,# ' "&0"!'o"y "!' & 22;%,/ 4& "y'% &'"0 & &o3, lo3/ T ,.' &'0 , & %!,!%,' &9
A. B. C. D. E.
Intravenous amiodarone Endotracheal intu#ation Cardioversion Intravenous digo-in Intravenous verapamil
Explanation: hen atrial fi#rillation /a#sent J1 'aves and irregular heart rate0 is associated 'ith hemodynamic compromise& the role of medical therapy is limited. Direct current cardioversion should #e the treatment of choice. Cardioversion is indicated 'hen the arrhythmia is poorly tolerated and or 'hen one anticipates that sinus rhythm can #e maintained& as 'hen atrial fi#rillation has #een of short duration& and 'hen it occurs in the a#sence of mar%ed atrial enlargement or severe mitral stenosis. Atrial fi#rillation usually re$uires higher energy for conversion /<>>6;>> )oules0 /Choice C0. /Choice A0 Amiodarone is a class 4 anti arrhythmic agent& 'hich is e-cellent for control of #oth atrial and ventricular arrhythmias. !he drug is used 'hen the atrial arrhythmia is sta#le and there is no hemodynamic compromise. Because the drug can also cause hypotension& its use in hypotensive patients is a relative contraindication. (nce the patient has #een cardioverted& amiodarone is an e-cellent drug to maintain normal sinus rhythm /",R0. /Choice B0 In the a#ove patient& endotracheal intu#ation is not indicated. !he atrial fi#rillation is the cause of lethargy and lo' #lood pressure and once treated& most patients immediately recover. /Choice D0 Digo-in is a poor drug for treatment of acute atrial fi#rillation 'ith hemodynamic compromise. Digo-in does not act for hours and the patient has to #e loaded 'ith the drug #eforehand. !he drug is more useful for chronic atrial fi#rillation 'hen the ventricular rate is already controlled. /Choice E0 Calcium channel #loc%ers are e-cellent for treating atrial fi#rillation 'hen there is no hemodynamic compromise evident. In the presence of hemodynamic compromise& these drugs should #e 'ithheld& as they are also negative inotropes.
Educational o#)ective*
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47
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
hen atrial fi#rillation is associated 'ith hemodynamic compromise& cardioversion is the treatment of choice.
48
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 41: A 6-y!"-ol# %!l co%& 'o ' %",cy "oo% 3' &##, o,&' o$ &+" c&' 0!,/ T 0!, & 1:;1: , &+"'y '!", , !l'y !,# "!#!'& 'o ' !ck/ 4 & ! k,o3, #!'c $o" 1: y!"& !,# & y0"',&+ $o" = y!"&/ 4& %#c!'o,& ,cl# ,&l, %'o0"olol !,# y#"oclo"o'!#/ 4& +'!l& !" PR9 =6;%,< BP9 1661?6 %%4 , & "' !"% !,# 1>6;: , & l$' !"%< T%0"!'"9 > C (?=/6@)< PR9 17;%,/ O, !&cl'!'o, l, $l#& !" cl!" !,# !"' &o,#& !" ,o"%!l 3'o' !,y %"%"&/ C&' .-"!y !,# EK !" ,o"%!l/ B!&& o, '& $,#,& 3c o$ ' $ollo3, & ' %o&' lkly #!,o&& o$ '& 0!',' A. B. C. D. E.
Angina pectoris Myocardial infarction Acute pericarditis Aortic dissection 1ulmonary em#olism
Explanation: E-planation* !his patient is most li%ely suffering from aortic dissection. !he most fre$uent predisposing condition for aortic dissection is hypertension. ,udden onset of severe tearing pain& 'ith radiation to the #ac%& is a typical presentation of aortic dissection. !he finding of a difference of more than 4> mmHg in the #lood pressure readings #et'een t'o arms is another important clue for the diagnosis of aortic dissection. 1ain of IHD usually feels li%e pressure and it typically radiates to the )a'& left shoulder or left arm. 1ain of angina occurs 'ith e-ertion and is relieved 'ith rest and su#lingual nitroglycerin. 1ain of Ml occurs at rest and is not fully relieved #y su#lingual nitroglycerin. E usually provides evidence for ischemic heart disease 'ith !6'ave inversion in angina pectoris& and ,! segment elevation or ,! segment depression in cases of Ml. !he nature of pain in the a#ove patient 'ith a#sent E changes ma%es the diagnosis of angina& or Ml& very unli%ely. 1ain in acute pericarditis is pleuritic& is 'orsened #y deep #reathing and coughing and is alleviated #y leaning for'ard. E may sho' ,! segment elevation that is concave up'ards 'ithout any reciprocal changes. 1ulmonary em#olism usually presents 'ith sudden onset of dyspnea& chest pain& tachycardia& and tachypnea. !here is usually a history of ris% factors li%e immo#ili+ation& surgery of hip or femur etc. that predisposes the development of pulmonary em#olism.
Educational (#)ective* ,uspect aortic dissection as a cause of tearing chest pain in the setting of H!" and B1 difference in the ; arms.
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49
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 42: A >:-y!"-ol# 3o%!, co%& 'o ' 0y&c!, c!& o$ ! 2-#!y &'o"y o$ 0, o"'!l #%! !,# !#o%,!l #&','o,/ S !& ,o o'" co%0l!,'&/ 4" '%0"!'" & >/1 C (?=/?@) loo# 0"&&" & 125;5%% 4 0l& & =:;%, !,# "&0"!'o,& !" 17;%,/ E.!%,!'o, &o3& !&c'&/ U",!ly&& &o3& 0"o',"!9 27-o" ",!"y 0"o', .c"'o, & 7 ;#!y 'o'!l &"% 0"o', & 5 ;#L !,# &"% !l%, & 2/5;#L/ A #!,o&& o$ ,0"o'c &y,#"o% & %!#/ R,!l o0&y & 0"$o"%#/ S & &'!"'# o, #"'c& !,# " &!l' !,# 0"o', ,'!k & "&'"c'#/ 4" #%! ,& 'o %0"o+/ 4o3+" ' 0!',' &##,ly #+lo0& &+" !#o%,!l 0!, $+" !,# "o&& %!'"!/ Wc o$ ' $ollo3, & ' %o&' lkly #!,o&& '!' 3ll "+!l# y ",!l o0&y A. B. C. D. E.
Minimal change disease ,ystemic amyloidosis Focal segmental glomerulosclerosis Mem#ranous glomerulonephritis Dia#etic nephropathy
Explanation: E-planation* Renal vein throm#osis is an important complication of nephrotic syndrome. Antithrom#in Ill is lost in the urine and puts patients at an increased ris% of venous and arterial throm#osis. Renal vein throm#osis presents 'ith sudden onset of a#dominal pain& fever and hematuria. It can occur in any form of nephrotic syndrome& #ut it is most common 'ith mem#ranous glomerulonephritis& 'hich is the most common cause of nephrotic syndrome in adults /Choice D0. /Choices A& B& C and E0 Minimal change disease& systemic amyloidosis& focal segmental glomerulosclerosis and dia#etic nephropathy can all cause nephrotic syndrome and su#se$uent renal vein throm#osis9 ho'ever& this complication is less fre$uent 'ith these disorders.
Educational (#)ective* Renal vein throm#osis is an important complication of nephrotic syndrome& 'hich is most commonly caused #y mem#ranous glomerulonephritis in adults.
50
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 43: A ;56year6old 'oman presents 'ith a one6'ee% history of dysuria and increased urinary fre$uency. ,he admits to having multiple se-ual partners in the past. Her temperature is 4.< C /K=.K F0& #lood pressure is <<>> mm Hg& pulse is 5=min& and respirations are <8min. E-amination sho's suprapu#ic tenderness. Mucopurulent discharge is o#served at the urethral os. @rinalysis sho's* Blood "egative lucose "egative etones "egative 3eu%ocyte esterase 1ositive "itrites "egative BC G>68>hpf RBC <6;hpf Bacteria "one @rine culture after ;G hours* Q<>> coloniesm3. hich of the follo'ing is the most li%ely diagnosis
A. B. C. D. E.
Acute pyelonephritis Acute #acterial cystitis Chlamydial urethritis onococcal urethritis !richomonal vaginitis
Explanation: !he diagnosis of chlamydial urethritis is usually suggested #y the presence of mucopurulent urethral discharge and history of multiple se-ual partners. Dysuria and urinary fre$uency can occur. @rinalysis reveals a#sent #acteriuria. @rine culture sho's less than <>> coloniesm3. /Choice A0 1atients 'ith acute pyelonephritis appear to-ic and present 'ith fever& nausea& vomiting& flan% pain& dysuria& and costoverte#ral tenderness. @rinalysis sho's #acteriuria and pyuria. @rine culture reveals greater than <>&>>> coloniesm3. /Choice B0 1atients 'ith acute #acterial cystitis present 'ith dysuria& urinary fre$uency& suprapu#ic discomfort and urinary findings of #acteriuria and pyuria. Mucopurulent cervical discharge is not found. @rine culture sho's colonies in e-cess of <>>>m3. /Choice D0 onococcal urethritis is less common than chlamydial urethritis. !he urethral discharge is purulent /rather than mucopurulent0& and ram stain usually reveals the causative organisms. /Choice E0 !he usual features of vaginitis are vaginal discharge& pruritus and dyspareunia. Increased urinary fre$uency is unusual.
Educational (#)ective* Chlamydial urethritis is suggested #y mucopurulent urethral discharge& a#sent #acteriuria& and history of multiple se-ual partners.
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51
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 44: A 67-y!"-ol# %!l 3' ! &'o"y o$ "%!'c $+" 0"&,'& 'o yo 3' ,"!l %!l!& !,# $,,y !"' "y'% $o" ' 0!&' 2 3k&/ 4 !# !, EC4O #o, l!&' y!" 3c "+!l# '!' !# %l# #" o$ %'"!l &',o&&/ 4 3!& %!,!# %#c!lly 3' #"'c&/ T loo# 0"&&" & 15:;=5%% 4/ 4& c"",' EK & &o3, lo3/ T ,.' &'0 , & %!,!%,' &9
A. B. C. D. E.
Cardioversion at 8( )oules 3idocaine Flecainide Carotid massage Diltia+em
Explanation: Atrial fi#rillation is due to the presence of macro re entry circuits. It is characteri+ed #y lac% of organi+ed atrial activity& 'ith atrial fi#rillatory 'aves& i.e. irregular undulation of the #ase line visi#le on the surface E. "o discrete J1: 'ave is seen and the JOR,: is irregularly spaced. !reatment of atrial fi#rillation in a hemodynamically sta#le patient is different from one 'ho is unsta#le. Anytime if the patient is hemodynamically unsta#le /lo' B1& patient not responding to commands0 treatment of choice is electrical cardioversion. If the patient is hemodynamically sta#le& then you have to thin% 'hether it is an acute process or a chronic process If it is an acute process then you can choose to convert the patient to sinus rhythm #y either cardioversion or you can %eep the patient under rate control. If it is a chronic process then it is #est managed 'ith rate control along 'ith anticoagulation. Cardioversion can #e either electrical or chemical. Electrical cardioversion /Choice A0 is indicated in hemodynamically unsta#le patients. Electrical cardioversion should not #e performed 'ithout 46G 'ee%s of anticoagulation in chronic atrial fi#rillation /7G= hours0& as 52
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
the ris% of em#oli+ation is high. !he re$uired )oules are a#out < >>6 ;>> )oules. Atrial fi#rillation is generally more resistant to convert to normal sinus rhythm than atrial flutter and the energy re$uired is much higher. 1atients do re$uire intravenous sedation #efore cardioversion. If you choose to do chemical cardioversion the #est drugs 'ould #e class Ill agents /amiodarone& sotalol& i#utilide etc.0. In the a#ove hemodynamically sta#le patient& the #est treatment is to administer intravenous diltia+em. He has these symptoms for a#out ; 'ee%s. ,o& he most li%ely has chronic atrial fi#rillation. ,ince he is not anticoagulated cardioversion should not #e attempted. ithin a fe' minutes to hours& the rate can #e controlled 'ith either I2 diltia+em /Choice E0 or #eta6#loc%ers /I2 metoprolol0. Digo-in is a good agent for patients 'ith heart failure /systolic dysfunction0 and atrial fi#rillation. /Choice B0* 3idocaine is a type& anti arrhythmic agent used mainly in the treatment of ventricular arrhythmias. It has no role in the treatment of atrial fi#rillation. 3idocaine is given intravenously or may even #e administered via the endotracheal tu#e /'hen no I2 access e-ists0. /Choice C0* Flecainide has #een associated 'ith sudden deaths and is rarely used in the clinical practice. It is a last resort for resistant arrhythmias. /Choice D0* !he role of carotid massage has declined in the last decade. It has no role in the management of atrial fi#rillation. Carotid massage has led to release of em#oli from the carotid pla$ues leading to stro%es and the maneuver is no' not recommended. Educational (#)ective* Anytime if the patient is hemodynamically unsta#le& treatment of choice is electrical cardioversion. If the patient is hemodynamically sta#le then you have to thin% 'hether it is an acute process (r a chronic process. If itis an acute process then you can choose to convert the patient to sinus rhythm #y either cardioversion or you can %eep the patient under rate control. If it is a chronic process then it is #est managed 'ith rate control along 'ith anti coagulation. Rate control is #est achieved 'ith diltia+em or metoprolol.
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53
USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 45: A 25-y!"-ol# %!, 0"&,'& 'o ' %",cy #0!"'%,' 3' ! '3o-#!y &'o"y o$ -"!# $+" 3' cll&/ 4 !#%'& 'o &, I #"& $o" ' l!&' '3o y!"&/ Py&c!l .!%,!'o, "+!l& ! olo&y&'olc %"%" !' ' c!"#!c !0./ O0'!l%o&co0y "+!l& .#!'+ #%!'o& %o""!c l&o,& o, ' "',!/ T& l&o,& !" ,o' #oc%,'# , & 0"+o& !l' +&' $o" &o" '"o!' o, %o,' !o/ Bloo# cl'"& !" 0o&'+ $o" S'!0ylococc& !"&/ T"!,&&o0!!l coc!"#o"!0y &o3& +'!'o,& o, o' ' '"c&0# !,# %'"!l +!l+&/ Wc o$ ' $ollo3, .0l!,& ' 0!'o0y&oloy o$ ' "',!l l&o,& , '& 0!',' A. B. C. D.
Coagulopathy Immune vasculitis ,eptic em#oli 2asospasm
Explanation: !he pathophysiologic conse$uences and clinical manifestations of infective endocarditis /IE0 can #e e-plained #y the follo'ing* <. Cyto%ine production& 'hich is responsi#le for constitutional symptoms /e.g.& fever0. ;. Em#oli+ation of vegetation fragments& 'hich lead to infection or infarction of remote tissues /e.g.& pulmonary and splenic infarcts0. 4. Hematogenous spread of infection during #acteremia. G. !issue in)ury from immune comple- deposition or immune response to deposited #acterial antigens. Roth spots are e-udative& edematous lesions on the retina. !hey appear as oval hemorrhages 'ith pale centers. !he underlying pathophysiology is an immune vasculitis. !hese lesions are an infre$uent finding in patients 'ith IE. !hey have also #een noted in patients 'ith collagen vascular disease and hematologic disorders& such as severe anemia. Immune activation is also thought to #e responsi#le for (sler:s nodes& I6associated glomerulonephritis& and the rheumatologic manifestations of IE. (sler:s nodes are violaceous nodules on the pulp of the fingers and toes thought to #e caused #y immune comple- deposition. /Choices A and D0 Coagulopathy and vasospasm are not responsi#le for the pathophysiology of Roth spots. /Choice C0 ane'ay lesions are macular& erythematous& #lanching& non6 painful lesions on the palms and soles. !hey are due to septic em#oli. ,u#cutaneous a#scesses are seen on histologic e-amination.
Educational (#)ective* Immunocomple- disease is primarily responsi#le for IE6associated glomerulonephritis& Roth spots& and (sler:s nodes. ane'ay lesions result from septic em#olism.
54
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USMLE WORLD STEP 2 CK 1*
(INTERNAL MEDICINE) *Block
Q NO 46: A ;;6year6old man comes to the urgent care clinic 'ith a one6 'ee% history of fever& sore throat. and malaise. He has tried several over6the6counter products 'ith partial relief. His temperature is 4=.=C /<>; F0& pulse is <<>min& respirations are <=min& and #lood pressure is <4>> mm Hg. (ropharyngeal e-amination reveals palatal petechiae 'ith strea%y hemorrhages and #lotchy& red macules. !he tonsils are enlarged and covered 'ith 'hitish e-udate. Mild )aundice is present. Enlarged lymph nodes are palpa#le posterior to the sternocleidomastoid muscle #ilaterally. A-illary lymphadenopathy is also present. A#dominal e-amination reveals normal #o'el sounds and mild hepatosplenomegaly. His complete #lood count is sho'n #elo'* Hemoglo#in g3 MC2 == fl 1latelets &>>>mm 3eu%ocyte count >mm "eutrophils 44 3ymphocytes 55 Eosinophils < hich of the follo'ing is commonly associated 'ith this patient:s condition
A. B. C. D. E. F.
Bronchopneumonia Autoimmune hemolytic anemia ,plenic infarction Hepatocellular carcinoma Dilated cardiomyopathy lomerulonephritis
Explanation: !he patient is suffering from infectious mononucleosis /IM0. IM is characteri+ed #y fever& sore throat& to-ic symptoms& and lymphadenopathy. !he characteristic distri#ution of lymph node involvement in IM is symmetric and involves the posterior cervical chain of lymph nodes more fre$uently than the anterior chain. Inguinal and a-illary lymphadenopathy can also #e present. (ther physical findings include pharyngitis& tonsillitis& and tonsillar e-udates. Mild palatal petechiae may #e found& #ut this is non6specific& and is also found in patients 'ith streptococcal pharyngitis. !onsillar enlargement can cause air'ay compression. Hepatitis and )aundice are present in a small percentage of cases. 1atients 'ith IM can develop autoimmune hemolytic anemia and throm#ocytopenia. Hemolytic anemia results from anti6I anti#odies against red #lood cells and is usually Coom#s:6test positive. /Choice A0 Bronchopneumonia can occur as a superinfection in patients 'ith IM. Ho'ever& it is very unusual. /Choice C0 ,plenic infarction does not occur in IM. (n the other hand& splenic rupture is one of the feared complications of IM& and trauma precedes half of such cases. Contact sports& such as soccer& should #e avoided. /Choice D0 Hepatocellular carcinoma is not associated 'ith EB2 infection. /Choice E0 Dilated cardiomyopathy is a possi#le complication of Coryne#acterium infection& 'hich presents as a sore throat 'ith pseudomem#rane formation. It is not seen 'ith EB2 infection. /Choice F0 lomerulonephritis is a complication of streptococcal pharyngitis.
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