Andersons pediatric cardiology 1378
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PapillaryFibroelastoma
Papillaryfibroelastomaisthesecondorthirdmostcommonadultprimary
cardiactumorandisprimarilyseenintheelderly.Thesetumorscanarisefrom
anyendocardialsurfacebutmostcommonlyarisefromthedownstreamsideof
theaorticandmitralvalves.Theyareoftenpedunculatedandhighlymobile.
Thistumorisexceedinglyrareinchildren,generallycomprisinglessthan2%of
allprimarytumors.5,10,117Inchildren,thesetumorshavebeenreportedonthe
tricuspid,mitral,andaorticvalves,aswellastherightatrium.Inbothadultsand
children,thesetumorsaremostfrequentlyasymptomatic.Symptomsarerelated
toembolizationoftumorfragmentsoradherentthrombusandrarelycardiac
obstruction.117,118Surgicalresectionisgenerallycurativeandwelltoleratedand
isrecommendedforsymptomaticpatients.Thereiscontroversyregardingthe
needforsurgicalinterventioninasymptomaticpatients,althoughtumormobility
hasbeenidentifiedasapredictorofembolicevents.119
BloodCysts
Althoughbloodcystshavebeendescribedascommonincidentalfindingson
autopsiesoffetusesandinfants,theyareexceedinglyrareincaseseriesof
pediatricprimarytumors.1,120Thesetumorsoccurmostcommonlyonthe
atrioventricularvalvesbuthavebeendescribedonallvalves.On
echocardiography,theseappearasroundedcysticlesionsandmayhaveinternal
calcifications.ReportsofcardiacMRIinpediatriccasesarecharacterizedby
hyperintensityonT2sequences(Fig.52.18).Thesetumorsaremostoften
thoughttohavenoclinicalsignificanceandregressspontaneously.Casereports
describelargecystscausingobstructiontofloworvalvarstenosis,usually
pulmonary.121
FIG.52.18 Bloodcyst(arrow)associatedwiththepulmonaryvalve.The
lesionappearscysticonechocardiogrambutmayappearsolidonMRI
sequences.Thistumorwasassociatedwithpulmonarystenosisand
regurgitation.Notethemainpulmonaryarterydilation(asterisk).
TumorsoftheAtrioventricularNode
Cystictumorsoftheatrioventricularnode,alsocalledmesotheliomasofthe
atrioventricularnode,areexceedinglyrare.Theyarethesmallesttumors
associatedwithsuddendeath,andmostofthecasesarediagnosedatautopsy.3
Immunocytochemicalstudieshavedemonstratedanepithelialpatternof
differentiation,suggestingthatthetermmesotheliomaisincorrect.Thecystwall
iscoveredbyasinglelayerofcuboidalepithelioidcellsandiscomposedof
fibrousconnectivetissueshowingfocusesofchronicinflammation.Withinthe
fibroustissuearesmallercystslinedbysimilarcuboidalcells,whichcontain
hyalineeosinophilicmaterial.3,122–124Themajorityofpatientshavepartialor
completeatrioventricularblockandoftendieeitherofcompleteheartblockorof
ventricularfibrillation.Cystictumorsoftheatrioventricularnodehavebeen
describedasoccurringatalmostanyage,fromnewbornto86years,withamean
ageatpresentationof38yearsandaratiooffemalestomalesof3to1.3,122The
tumors,althoughsmall,canbedetectedbyechocardiographyorMRI.122,124In
symptomaticpatientswithheartblock,apacemakercanbeimplanted,albeitthat
pacinghasnotalwayspreventeddeath.122Indeed,itisnotalwayswelltolerated,
andventricularfibrillationmayensue.124Forthesereasons,cystictumorsofthe
atrioventricularnodehaverecentlybeensurgicallyexcisedwithsuccess.122,124
PurkinjeCellTumors
Thesetumorsareknownunderavarietyofterms,includingoncocytic
cardiomyopathy,histiocytoidcardiomyopathy,foamymyocardial
transformation,infantilexanthomatouscardiomyopathy,andfocallipid
cardiomyopathy.1,31Theyarerare,andtodate,fewerthan100caseshavebeen
described.1Mostcaseswerereportedininfantsyoungerthan2years,withmore
than75%foundinfemales.125Theyareassociatedwithtachyarrhythmiasand
maygiverisetoincessantventriculartachycardiaorsuddendeath.Theetiology
remainscontroversial.Ithasbeenproposedthattheymightarisefromadisorder
ofmitochondrialmetabolism.Inaddition,becauseoftheassociationbetween
histiocytoidcardiomyopathyandanX-linkedchromosomaldisorder,including
microphthalmiawithlinearskindefect,anabnormalityinthep22regionofthe
Xchromosomehasbeensuggested.125
Pathologicexaminationofthetumorischaracterizedbythepresenceof
subendocardialnodulesthatmaybediscreteordiffusethroughouttheventricles,
withincreasedweightoftheheart.126Thetumorsinvolvemostfrequentlythe
conductionsystemandtheleftventricle.Histopathologyrevealsclustersof
vacuolatedhistiocytoid-likecellswithdecreasedbundlesofmyofibril.1,125,126
Ultrastructurally,thecellscontainanincreasednumberofmitochondria.
Themostcommonclinicalpresentationiswitharrhythmiaandsudden
death.1,127Ventricularfibrillation,ventriculartachycardia,Wolff-ParkinsonWhitesyndrome,prematureventricularbeats,supraventriculartachycardia,and
heartblockhaveallbeendescribed.1,126Involvementofotherorganshasbeen
reported.Extracardiacandcardiacmalformations,suchasventricularandatrial
septaldefects,leftventricularnoncompaction,endocardialfibroelastosis,and
hypoplasticleftheartsyndrome,havealsobeendescribed.125
Diagnosismaybedifficultbutshouldbesuspectedinfemaleinfantswith
tachyarrhythmias,especiallyifechocardiographyrevealsnodulardepositsonthe
ventricularendocardiumorvalves.1Accurateexaminationofthecardiac
conductionsystemisparamounttofindthemechanismsresponsibleforsudden
cardiacdeathininfancy.1,127Prognosisisbleak,andwithouttreatment,the
tumorsusuallyresultindeathbytheageof2years.1,106Whenthetumoris
resectable,surgicalexcisionhasbeenperformedwithsuccess.1,125
PrimaryMalignantTumors
Primarymalignanttumorsoftheheartareextremelyrareininfancyand
