Focalnodularhyperplasia(FNH)

Outline

FNHaccountsforapproximately8%ofallprimaryhepatictumorandisthesecondmostcommonbenignlivertumorafterhemangioma.

Thisbenigntumouroccursmostcommonlyinwomenaged20–50years,butmayoccurinbothmenandwomenatanyage,withmultiplelesionsbeingfoundin20percentofcases.FNH

Oralcontraceptive口服避孕藥useisassociatedwithFNHbuttheresponsibilityoforalcontraceptivesintheoccurrenceofthelesionhasnotbeendemonstrated.

well-circumscribedlobulatedmasswithcentralscar(arrow)andradiatingseptations.

PathologicalappearanceFNHisdefinedasanodulecomposedofbenign-appearinghepatocytesoccurringinaliverthatisotherwisehistologicallynormal.FNHisahyperplasticliverparenchyma（增生性肝實(shí)質(zhì)）subdividedintonodulesbyfibrousseptathatmayformstellatescars（星狀瘢痕）.Thelesionisusuallysolitary(80%)andmeasureslessthan5cmindiameter.Occasionally,FNHispedunculated(蒂).Photomicrographofhistopathologicspecimenshowsregionsofnodularhepatocellularproliferationseparatedbyradiatingbandsandsurroundingmyxomatousscar(arrows).FNHclassic(80%)non-classic(20%)

(a)telangiectaticFNH,

(b)withatypia,

(c)mixedhyperplasticandadenomatousFNH

Diagnosis（CT）NonenhancedCTscansFNHisdemonstratedasafocalhypodenseorisodensemasscomparedwithnormalliver.Acentralhypodensescarisdepictedinonlyone-thirdofthecases.Calcificationswithinthecentralscarareveryrareandobservedinonlyabout1%ofthecases.contrast-enhancedCTscanarterial

phaseThelesionenhancesrapidlyinmostcasesandthelesiontolivercontrastishigh.Lesioncontouriswelldemarcatedandmaybelobulated.Atthattime,thecentralscarishypodenseandappearsmoreevidentthanonunenhancedCTscans.

delayed

phase

FNHareisodenserelativetonormalliverandinmostcases,centralscarsappearisoorhyperattenuating.Acentralscarisobservedmoreofteninlargelesionsthaninsmalllesions.CTT1WIT2WI

Diagnosis（MRI）NonenhancedMRIscans

TypicalFNHsareisoorhypointenseonT1WIandisoorslightlyhyperintenseonT2WI.

ThecentralscarishypointenseonT1WI

andstronglyhyperintenseonT2WI.Atypicalformsscarsareseeninmorethan80%ofcases.However,radio-pathologicpapershavedemonstratedthatsomeFNHmayhavenoscarevenatpathologyespeciallyFNHmeasuringlessthan3cmindiameter。

Rarely,scarsremainhypodenseorisodenseondelayedscansorarehypointenseonT2-weightedimages.Thesefindingsmaybeobservedupto20%ofcases.

NearlyallFNHsarehypervascularatthearterialphaseoftheenhancement,butlesionenhancementmayvaryattheportalphaseorondelayedimages.Bothhypodensityorintensityofthemassondelayedphase,oronbothportalveinanddelayedphaseimagesaswellashyperdensity-intensityofthemassontheportalveinphaseoronbothportalveinanddelayedphasesmaybeseen.

Differentialdiagnosis肝囊腫Hepaticcyst

原發(fā)性肝癌primaryhepaticcarcinoma肝囊腫Hepaticcystnoncontrast-enhancedcontrast-en