fnh肝局灶性结节性增生电子教案

肝局灶性结节性增生Focalnodularhyperplasia(FNH)

Outline

FNHaccountsforapproximately8%ofallprimaryhepatictumorandisthesecondmostcommonbenignlivertumorafterhemangioma.

Thisbenigntumouroccursmostcommonlyinwomenaged20–50years,butmayoccurinbothmenandwomenatanyage,withmultiplelesionsbeingfoundin20percentofcases.FNH

Oralcontraceptive口服避孕药useisassociatedwithFNHbuttheresponsibilityoforalcontraceptivesintheoccurrenceofthelesionhasnotbeendemonstrated.

well-circumscribedlobulatedmasswithcentralscar(arrow)andradiatingseptations.

PathologicalappearanceFNHisdefinedasanodulecomposedofbenign-appearinghepatocytesoccurringinaliverthatisotherwisehistologicallynormal.FNHisahyperplasticliverparenchyma（增生性肝实质）subdividedintonodulesbyfibrousseptathatmayformstellatescars（星状瘢痕）.Thelesionisusuallysolitary(80%)andmeasureslessthan5cmindiameter.Occasionally,FNHispedunculated(蒂).Photomicrographofhistopathologicspecimenshowsregionsofnodularhepatocellularproliferationseparatedbyradiatingbandsandsurroundingmyxomatousscar(arrows).Themarginissharp,oftenlobulatedandnocapsuleispresent.Hemorrhageandnecrosisarerare.Atmicroscopy,thecentralfibroticzoneisdenseconnectivetissue（致密结缔组织）whichcontainsnumerousabnormallythickwalledarteries.Markedproliferationofbiliarystructuressurroundedbyinflammatorycellsisobservedwithinandattheperiphery（边缘）ofthefibrousseptae.Kupffercellsarealsoseenwithinthelesion.FNHclassic(80%)non-classic(20%)

(a)telangiectaticFNH,

(b)withatypia,

(c)mixedhyperplasticandadenomatousFNH

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

phaseThelesionenhancesrapidlyinmostcasesandthelesiontolivercontrastishigh.Lesioncontouriswelldemarcatedandmaybelobulated.Atthattime,thecentralscarishypodenseandappearsmoreevidentthanonunenhancedCTscans.

portalvenousphaselesionenhancementdecreasesandthelesionmaybeeitherisoorslightlyhyperdenserelativetonormalliver.Small-sizedFNHmaybebarelyvisible,whereaslarge-sizedFNHarevisualizedduetodeformityinthelivercontourordisplacementofadjacentvesselsordepictionofarelativelyhypoattenuatingcentralscar.

delayed

phase

FNHareisodenserelativetonormalliverandinmostcases,centralscarsappearisoorhyperattenuating.Acentralscarisobservedmoreofteninlargelesionsthaninsmalllesions.CTT1WIT2WI

Diagnosis（MRI）NonenhancedMRIscans

TypicalFNHsareisoorhypointenseonT1WIandisoorslightlyhyperintenseonT2WI.

ThecentralscarishypointenseonT1WI

andstronglyhyperintenseonT2WI.contrast-enhancedMRIscandramaticenhancementinthearterialphase,followedbyisointensityofthelesionduringtheportalvenousphase.Ondelayedphaseimaging,thecentralscarshowshighsignalintensity.Atypicalformsscarsareseeninmorethan80%ofcases.However,radio-pathologicpapershavedemonstratedthatsomeFNHmayhavenoscarevenatpathologyespeciallyFNHmeasuringlessthan3cmindiameter。

Rarely,scarsremainhypodenseorisodenseondelayedscansorarehypointenseonT2-weightedimages.Thesefindingsmaybeobservedupto20%ofcases.

NearlyallFNHsarehypervascularatthearterialphaseoftheenhancement,butlesionenhancementmayvaryattheportalphaseorondelayedimages.Bothhypodensityorintensityofthemassondelayedphase,oronbothportalveinanddelayedphaseimagesaswellashyperdensity-intensityofthemassontheportalveinphaseoronbothportalveinanddelayedphasesmaybeseen.

AlthoughFNHisanon-encapsulatedlesion,capsulelikeenhancementmaybeobservedonportalveinandondelayedphasescansinabout25–36%ofthecases.Thepseudocapsule(假包膜)ishypointenseonT1andslightlyhyperintenseonT2.

Differentialdiagnosis肝囊肿Hepaticcyst

原发性肝癌primaryhepaticcarcinoma肝囊肿Hepaticcystnoncontrast-enhancedcontrast-enhancedCTnonen