w w w . r b o . o r g . b r
Case
report
Tumor
formation
in
Hoffa’s
infrapatellar
fat:
Case
report
夽
Alan
de
Paula
Mozella
∗,
João
Victor
da
Silveira
Moller,
Hugo
Alexandre
de
Araújo
Barros
Cobra
NationalInstituteofTraumatologyandOrthopedics,RiodeJaneiro,RJ,Brazil
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received27February2014
Accepted22April2014
Availableonline31January2015
Keywords:
Adiposetissue
Osteochondroma
Synovialchondromatosis
a
b
s
t
r
a
c
t
Althoughtumorsorpseudotumorallesionsarerareintheinfrapatellarfat,theymayaffect
it. Osteochondromais thecommonest benignbonetumor.However, extraskeletal
pre-sentationsare rare.Therearethreeextraskeletalvariantsofosteochondroma:synovial
chondromatosis,para-articularchondromaandsoft-tissuechondroma.Wepresentacase
ofasingleintra-articularlesionintheareaofHoffa’sfat,ina78-year-oldfemalepatient
withacomplaintofprogressivekneepainassociatedwithseverearthrosis.Fromthe
clin-icalandradiologicalfindings,thediagnosiswaspara-articularosteochondroma.However,
thehistopathologicalfindings,afterexcisionofthelesion,showedthatthiswassynovial
chondromatosissecondarytoosteoarthrosis.
©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora
Ltda.Allrightsreserved.
Tumorac¸ão
na
gordura
infrapatelar
de
Hoffa
–
Relato
de
caso
Palavras-chave:
Tecidoadiposo
Osteocondroma
Condromatosesinovial
r
e
s
u
m
o
Tumoresoulesõespseudotumorais,apesarderaros,podemacometeragordura
infrapate-lar.Oosteocondromaéotumorósseobenignomaiscomum.Entretanto,suaapresentac¸ão
extraesqueléticaérara.Trêssãoasvariantesdoosteocondromaextraesquelético:a
condro-matosesinovial,ocondromapara-articulareocondromadepartesmoles.Apresentamos
umcasodelesãointra-articularúnicanatopografiadagorduradeHoffaemumapaciente
femininade78anoscomqueixadedorprogressivaemjoelhoassociadaaartrosegrave.Pelos
achadosclínicoseradiológicosodiagnósticofoideosteocondromapara-articular.
Entre-tanto,osachadoshistopatológicos–apósexéresedalesão–evidenciaramcondromatose
sinovialsecundáriaaosteoartrose.
©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevierEditora
Ltda.Todososdireitosreservados.
夽
WorkdevelopedattheKneeSurgeryCenteroftheNationalInstituteofTraumatologyandOrthopedics,RiodeJaneiro,RJ,Brazil.
∗ Correspondingauthor.
E-mail:[email protected](A.P.Mozella).
http://dx.doi.org/10.1016/j.rboe.2015.01.006
Introduction
Theinfrapatellarfatpad,alsoknownasHoffa’sfat,isan
intra-articularandextrasynovialstructurethatformspartofthe
anteriorcompartmentoftheknee.
Themainailmentsthat affect Hoffa’sfat are
degenera-tivejointdisease,inflammatorypathologicalconditionsand
sequelaeoftrauma.Tumors orpseudotumoral lesionsmay
alsoaffectthisfatpad,althoughthesearerare.
Because ofabundant innervation, these alterations
fre-quentlypresentsignificantsymptoms,althoughthepresence
ofcalcificationshasonlybeenreportedinasmallnumberof
cases.
Here,wereportonacaseofasingleintra-articularlesion
intheanteriorcompartmentthatwasassociatedwithsevere
arthrosis.
Case
report
Thepatientwasa78-year-oldblackwomanwithhypertension
anddiabeteswhocomplainedofprogressivepaininherleft
kneethathadbeenevolvingoveraperiodofmorethan6years,
inassociationwithfunctionallimitation.Onphysical
exami-nation,heraxiswasseentopresentvalgusof15◦andshehad
muscleatrophyof++/3+.Shehadapainfulrangeofmotion
from 10◦ to 130◦,which wasassociatedwithcrepitation in
threecompartments.Palpationshowedthatthevolumeinthe
infrapatellarregionwasgreaterthannormal,withhardened
consistencyandlimitedmobility.
Fig.1–(A)Anteroposteriorradiograph.(B)Lateral-viewradiographoftumorformationintheanteriorcompartmentofthe knee.
Radiographicexaminationsshowedacalcifiedoval-shaped
infrapatellar image with well-delimited outlines, and also
hypodenseareasassociatedwithdegenerativealterationsand
jointpinchinginthelateralfemorotibialspace.Examinations
on the patient from 3 years earlierdocumented the same
lesionandshowedthattherehadnotbeenanyradiographic
alterationsoverthepast36months(Fig.1).
Because the lesion presentedbenign characteristics,we
chosetoresectiten-blocandperformtotalkneearthroplasty
withinthesameoperation.Amedialparapatellaraccessto
the left knee was opened and this showed a mass with
hardenedcharacteristics,visiblelaminasinthecartilage,
well-defined outlinesand lackofadherence todeepplanes.We
didnotidentifyanycommunicationwiththefemurortibia
(Fig.2).
Aftertumorresectionandimplantationoftheprosthetic
component,thepatientevolvedwithoutcomplications(Fig.3).
Anatomopathological examination revealed a nodule
with a knobbly surface of whitish gray color, measuring
3.3cm×2.5cm. After sectioning, it was seen to have a
stratified appearance of hardened consistency and there
was alsoacentralcavitymeasuring1.6cm×0.5cm(Fig.4).
Under a microscope, the nodule was seen to be formed
by typical chondrocytes that were immersed in a
chon-droid matrix and distributed in a stratified manner, with
areas of calcification, ossification and degeneration, and
withformationofpseudocysts.Thelesionwascoveredbya
synovialmembraneanditdisplayedflattenedcoatingcells.
Thediagnosiswasconcludedtobesynovialchondromatosis
Fig.2– Intraoperativeappearanceofthelesion.
Discussion
Osteochondromasare the commonestbenign bonetumors
andareoftenlocatedinthemetaphysealregionofthelong
bones.However,extraskeletalpresentationsofthesetumors
arerare.1Therearethreevariantsofextraskeletal
osteochon-droma:synovialchondromatosis, para-articularchondroma
andsoft-tissuechondroma.2
Synovial chondromatosis of the knee is an uncommon
entity.Knowledgeonthissubjectisbasedonreportsonsingle
casesorsmallseriesofcases.Itisdefinedasbenign
prolif-erationofmultiplecartilaginousbodiesinthesynovialtissue
thatispresentinjoints,bursasortendinoussheaths.3 Itis
believed thatfreecartilaginousfragmentsinjointsundergo
calcificationand/orossificationthroughtheprocessof
meta-plasiaformation.3
Theprocessofmetaplasiaformationcanbedividedinto
threephases:confinedtothesynovialmembrane;activation
ofthesynovialmembrane;progressiontofreebodies;anda
latestagewithaninactivesynovialmembraneandresidual
freebodies.4
Milgram divided synovial chondromatosis into three
categories:(a)freebodiesoriginatingfromosteochondral
frac-tures; (b) degenerative arthritis or avascular necrosis that
Fig.4–(A)Anatomicalspecimen.(B)Sectionsthroughthespecimenshowingcentralcavity.
leads to fragmentation of the cartilage; (c) primary
syno-vialchondromatosis.4Incasesofchondromatosissecondary
to osteoarthrosis, aspresented here, metaplasia is formed
infragmentscomingfrom subchondralfracturesorin
frag-mentedcartilage.4
Theclinicalconditiongenerallyaffectsasinglejoint.The
kneesarethe mostfrequentlocation,followedbythehips,
shoulders and elbows.5 This condition affects individuals
betweentheirthirdandfifthdecadesoflife,and especially
males.5,6 The symptoms are pain, edema and limitations
ontherangeofmovement.5,6 Theresultsfromthephysical
examinationrange from normal toa finding ofa palpable
mass.5
Theradiographicfindingscomprisemultiplelesionsthat
areroundedoroval-shaped,ofregularoutlineandwitha
cal-cifiedappearance.Themaindifferentialdiagnosisforsynovial
chondromatosisissynovialsarcoma,inwhichthe
calcifica-tionisirregular,coarseandgenerallyextra-articular.3
The treatment is surgical, with excision of the lesions,
preferably combined with total synovectomy.6 Partial
syn-ovectomyhasbeencorrelatedwithgreaterrecurrenceofthe
lesions.7
Para-articular osteochondromasare oftenlocated inthe
knees,butcasesintheelbows,hipsandankleshavealsobeen
reported.8Around50casesofpara-articularosteochondromas
havealreadybeendescribed.8Hoffa’sfatisthemostprevalent
locationintheknees.8Thepresenceofresidualsynovialtissue
possiblydemonstratesthattheprimaryneoplasticconditions
originatedinandwereconfinedtothisstructure.9
Reith et al.2 defined three criteria for diagnosing
para-articular osteochondroma:a single lesion,as seen
radiolo-gically and clinically; histologically composed ofbone and
cartilaginous tissue; and presentation as an extrasynovial
lesion.
Thenomenclatureusedtodescribethisconditionis
con-fusing.Similarlesionshavepreviouslybeenreportedas
capsu-larosteochondroma,extraskeletalosteochondroma,ossifying
chondroma, para-articular chondroma, giant extrasynovial
intra-articularosteochondromaandHoffa’sdisease.1
Completeresolutionofthesymptomsoccursinthe
major-ityofthecases,aftercompleteexcisionofthelesion.Lesion
recurrenceisarareevent.1,10
It is believed that because of the clinical,
radiologi-calandhistopathologicalsimilaritybetweenHoffa’sdisease
andintra-articularchondromas,theseconditionsareclosely
related.Mechanicalalterationssuchasvalgusorrecurvatum,
and rotational instability, contribute towardincreasing the
impactbetweenthesestructures.10
Theradiologicaldiagnosisisbasedonviewingthe
osteo-chondromainitscorrespondingsetting,butitonlybecomes
visibleaftertheprocessofossification.10Histologically,
trabec-ulatedbonethatischaracteristicofendochondralossification
ispresented,withacoveringofhyalinecartilage.1,8
Wethereforeconclude that,inthe casepresentedhere,
theradiographicfindingsofasinglelesionand itslocation
insideHoffa’sfatfavoradiagnosisofpara-articular
osteochon-dromasecondarytoHoffa’sdisease.However,histologically,
thelesionwascompatiblewithsynovialchondromatosis.This
diagnosiswasprobablyrelatedtotheassociatedconditionof
severeosteoarthrosisoftheknee.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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2.ReithJD,BauerTW,JoyceMJ.Paraarticularosteochondromaof theknee:reportoftwocasesandreviewofliterature.Clin OrthopRelatRes.1997;(334):225–32.
3.PerryBE,McQueenDA,LinJJ.Synovialchondromatosiswith malignantdegenerationtochondrosarcoma.JBoneJointSurg Am.1988;70(8):1259–61.
4.MilgramJW.Theclassificationofloosebodiesinhuman joints.ClinOrthopRelatRes.1977;(124):
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5.LewisM,MarshallJ,MirraJM.Synovialchondromatosisofthe thumb.JBoneJointSurgAm.1974;56(1):180–3.
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Arthroscopy.1994;10(2):166–70.
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