,,Endometrial maldifferentiation" - A clinically significant diagnosis in

H .-A . S choon et al .
Pferdeheilkunde15 (1999) 6 (November/Dezeml:er)
555-559
,,Endometrialmaldifferentiation"- A clinicallysignificant
diagnosisin equine reproduction?
H.-4. Schoon, DorisSchoon, lsabell Wiegandt,C.-P. Baftmann. and HeikeAupperle
InstitutfürVeterinärPathologie
def Universität
Leipzigi'Klinikfür Pferdedef Tieräztlichen
Hochschule
Hannover
Summary
The present paper describesthe functionalmorphologyof endometrialmaidifferenUation
in maresaccordingto the classificationof Schoon
et al. (1998).The ptimarydiagnosisis based on the investigationof routinelyH.-E. stainedslides,supplementedby immunohistological
techniques (estrogenand progesterone-receptors,
Ki-67 antigen,intermediatefilaments,laminin)of formalin-fixedbiopsy specimens.The morphologicalfindingsare interpretedas indicalivefor hormonaldisturbancesdue to ovarianneoplasmsand variousovariandystrophies,or as
a symptom of alterationsaffecungeither the hypothalamo-pituitary-ovarian-endometrial
axis or the local steroid hormone receptor status.
Clinicalsymptomsare mostly absent in cases without ovarianabnormalities.No relationshipcan be identifiedbetweenendometrialmalditfe
rentiationand the age or parity of the mare or season.From the authors' point of view endometrialmalditferentiation
should be taken into
account in the assessmentof endometrialbiopsy specimens as one important parameter leading to temporary or permanent fertility
problems.In a certain case, however,the definiteprognosiswith respect to reversibilityremainsunclear,because the aetiopathogenesis
has not yet been identifiedexcept for those cases of endocrineactive ovarianneoplasms.In this field an intensifiedco operationbetween
cliniciansand pathologistsis necessary.Especiallysystematiccase control studies, includingendocrinologyand determinationof foaling
ratesmay revealfurtherunderstandingresultingin efficientplans of treatments.
Keywords:
endometrium,maldifferentiation,
steroidhormonereceptors,fertilitydisorders,horse
,,EndometrialeFehldifferenzierung"- Eine klinisch relevante Diagnose in der equinen Reproduktionsmedizin?
Entsprechendder Einteilungvon Schoon et al. (1998)wlrd die funktionellelvlorphologieeiner endometrialenFehldifferenzierung
unter dem
(UED)"und einer ,,irregulären
(lED)"beschrieben.
Bild einer ,,ungleichmäßigen
endometrialenDitferenzierung
endometnalenDifferenzierung
Die primäreDiagnosebasien auf der Untersuchungvon H. E.-gefärbtenhistologischenSchnitten,sie wkd ergänztund präzisiertdurch immunhistologischeTechnikenam formalinfrxierten
Biopsiematerial(Oslrogen-,Progesteronrezeptorstatus,
Expressionvon Ki-67 Antigen,
Nachweisvon Intermediärfilamenten
und Laminin).Die histopathologischen
Befundewerden,je nach Lage des Falles,als Hinweisfür hormondle lmbalancenbei Ovartumoren,eine ovarielleDystrophie,eine Störungdes HypothalamusHypohysenOvar-Endometrium-Regelkreises bzw. als AusdruckeinerlokaienStörungdes endometrialenSteroidhormonrezeptorstatus
interpretiert.HinweisendeklinischeSymptome
mit AusnahmederjenigenStuten,die an klinischmanifestenStörungender Ovarfunktionleiden,fehlenzumeist.Ein Zusammenhangkonnte
weder zum Alter der Patientinnennoch zum Reproduktionsstatus,
der Paritätoder der Jahreszeithergestelltwerden. DieAutorenhalteneine
Berücksichtigungdes Befundes
für dringenderforderlich,
bei der Beudeilungvon Endometriumbiopsien
'endometrialeFehldifferenzierung"
da diesesErscheinungsbild
nach eigenenErfahrungenmit vorübergehenden
oder permanentenFertilitätsproblomen
einhergeht.Die Ursache
kann, mit Ausnahmedes VorliegensendokrinaktiverOvartumoren,dezeit im Einzelfallnoch nicht sicher ermitteltwerden. Hierzubedarf es
einer intensivenKooperationKlinik-Pathologie,
insbesonderedurch gezielteVerlaufsuntersuchungen
unter Einbeziehungder Endokrinologie
sowie der Abfohlergebnisse,
um zukünftigeinendem EinzelfallangemessenenTherapieplanentwickelnzu können.
Schlüsselwörter:
Pferd
Endometrium,Fehldifferenzierung,
Steroidhormonrezeptoren,
Fertilitätsstörungen,
Introduction
For years it has been well-established
in numerousreports
that endometritisand endometrosisare imoortantcauses
for fertilityproblems in the mare. Functionaldisturbances
however,have so far playeda minor role in equinediagnostics and research.In human gynaecopathology
such alterationsare well known as possiblecauses of infertility.Ovarian dysfunctions and tumours, central defects, hormone
refractiveendometria and hormonal treatments result in
greatlyvaryingbut ,,specific"morphologicalchangesin human beings (Dallenbach-Hellweg,1987).
Duringseasonalequine ovulatorycycles,the endometrium
proliferatesand differentiatesin response to physiologic
changes in estrogen and progesteronelevels(Brunckhorst
et al., 1991).lt reacts immediatelyto hormonalcyclicalvariationsas well as to disturbances(Schoonet al., 1999)and
hormonaltreatment(Kluget al., 1997).
Pferdeheilkunde
15
In this way the endometrialbiopsy servesas a distinctbiothe hormonesat the tissue level.Thereassay,,measuring"
fore the estimationof the endometrialstage -"dating the
endometrium" and the determination of endometrial
differentiation
as physiologicalor as pathologicalmust be
the first steps in the investigationof each biopsy sample
(Schoonet al., 1999).
Methods
In routine biopsy examinationendometrialmaldifferentiations are detectableby means of histopathology(HE, PASalcian-blue,Picro-SiriusRed stain). Additional investigametions usingnewlyestablishedimmunohistopathological
thods, i ,e. i ntermedi ate
fi l aments(vi menti n,desmin) ,lam i-
555
- A clinically
Maldifferentiation"
significant
diagnosisin equinereproduction?
,,Endometrial
nin, estrogen(ER)and progesteronereceptors(PR)and the
proliferation marker Ki-67 antigen (Ozgen et al., 1997;
Schoon et al., 1997; Schoon et al., 1998; Aupperle et al.,
1999) are additionallyhelpful.These techniquesare applicable to specimensfixed in neutral,bufferedformalin,even
in routinediagnostics.Bouin-fixative
however,recommended for years(Schoonet al., 1992)whilstprovidingsuperior
ce l l u l ardet ailslim it st h e p o s s i b i l i ti eos f i m m u n o h i stol ogy.
Thereforeit should be avoided even for routinediaqnostic
purposes.
Classification
According to Schoon et al. (1999)two major featuresof endometrialmaldifferentiation
exist based on findingsin H,-E.stainedslides:unequaland irregularendometrialdifferentiation. Endometrialmaldifferentiations
as describedhere are
exclusivelythose which occur in endometrialareaswithout
fibrosis,
any periglandular
In cases of unequaldifferentiation
in one biopsysampletwo
functionalstagesare obvious:areasdifferentiated
in accordance with the stage of the ovariancycle and multiplenon
fibroticfoci of glands deviatedeitherin degreeor qualityof
pattern.
activityfrom the dominantphysiological
tria (Aupperle, 1997), The ER and PR reactivityof the unaffected glands resemblestypical findings of the normal
proliferationphase. In many glands the lamininlabellingof
the basal lamina is remarkablv low and often disconti nuous.
The irregular differentiationis characterised by a diffuse
glandularalterationaffecting all or at least most of the
glands within a specimen.Abnormalproliferative
or secretory activitymay be present, in other cases patterns occur
which cannot be appointedto any kind of physiological
differentiation.Correspondingsubdivisionswere made based
on the dominatingsigns of endometrialfunctionalmorphology.
The most obvioussign of irregularproliferative
differentiation is the distinct polymorphismof the glandularepithelia.
Within a single gland longish,oval and round, hyperchromatic and hypochromaticnuclei occur in basal, mid and
apical positions(Fig. 1). Their lininghas lost its orderlyarrangement.Glands with hyperplasticepitheliaand numerous mitosesmay be present.
The epithelialexpressionof Ki-67 antigen is very intense
and correspondswith high valuesof estrogenreceptorsof
the glands and low levelsin the stromalcells (Fig.2). The
expressionof the progesteronereceptor is pathologically
low.
*s#
': f*,
*t,q'
4..q
Fig.1:
lrregularproliferative
Poly- Fig 2:
endometrial
differentiation.
morphicglandular
epithelia
showlongishor oval,mostly
hyperchromatic
nucleiin basal,mid or apicalpositions
mitoses.
H.-E.stain,magnification
andnumerous
3O0x
lrregulärproliferative
Differenzierung.
Die
endometriale
Drüsenepithelien
sind polymorphmit länglichen
oder
ovalen,meisthyperchromatischen
Zellkernen
in basaler,
mittlerer
H.-E.Färbuno.
oder aoikalerPosition.
Gerätevergrößerung
300x
Frequentlythese glands are closelyapposed forming non
fibrotic nests, lacking distinct borders to the adjacenttissue. Epitheliaas well as stromal cells express high values
however,an intense
of estrogenreceptors.Physiologically
expressionin the epitheliais correlatedwith a weak stromal reaction and vice versa (Aupperleet al., 1999).The labellingof the proliferationmarker Ki-67 antigenis unusually low. The stromal cells show an unphysiological
expression of desmin. lt is reportedthat desmin-positivestromal
cells occur in mares with pathologicallyinactiveendome-
556
lrregular proliferative endometrial differentiation. The
epithelialexpressionof ER is rather uniform and high,
stromalcellsshow a weak expression.lmmunohistology,
estrogen receptor expression, Nomarski-interferencecontrast,magnification
62.5x
lrregulär proliferative endometriale Differenzierung.
Während die Eoithelzelleneine hohe Exoressionvon
Östrogenrezeptorenzeigen, reagierendie Stromazellen
nur schwach positiv. lmmunhistologie,Östrogenrezeptornachweis, Nomarski InterJerenzKontrast. Gerätevergrößerung62,5x
In cases of an irregular secretory differentiation, large and
highly secretory glands dominate, The glandular epithelia
are of enormous height, the pale cytoplasm contains numerous vacuoles. Large, round and hypochromatic nuclei are
intermingled with depolarised nuclei of various shape and
chromatin density (Fig. 3). Although a secretory morphology
is obvious, an intense epithelial estrogen receptor expression and proliferationactivity is present (Fig, a).
P ferdehei l k unde' 15
- A clinically
Maldifferentiation"
diagnosisin equinereproduction?
significant
,,Endometrial
tiology in a certain case (Dallenbach-Hellweg,1987),comparableinvestigations
are lackingin the horse,There is little
informationabout endometrialdifferentiation
disorders.Endometrial atrophy during the late physiologicalbreeding
Tab.1: Histopathological
type of endometrial
maldifferentiationseason as a result of hormonal refractive endometrium
(Schoonet al., 1997) and endometrialhypoplasiaand hyoccurringspontaneously
or in the courseof ovariandiperplasiaare repofted (Ricketts,1975; Kenney, 1978).Thus
SEASES.
these
descriptionsdo not correspondwith the phenomena
Histopathologische
Charakterisierung
der endometrialen
of unequalor irregularendometrialdifferentiation
as defined
Fehldifferenzierung
bei Spontanfällenund im VerlaufovariellerErkrankunoen.
here. Focal hypertrophyand atrophy occur in glands affected by endometroticlesions(Kenney, 1978; Schoon et al.,
Morp h o l o g i c a l
3pontaneous Ovarian
Ovarian
1997).These glands are known to undergo processesof
classification
cases
neoplasms dystrophy
maldifferentiation
as well, however,due to other pathome(n)
(n)
(n)
(Aupperle
chanisms
et al., 1997).
It is supposedthat diffuseirregularendometrialmaldifferenNormalendometrial
tiationsare resultsof hormonaldisturbancesincludingthose
differentiation
2
resultingfrom hormonallyactiveovarianneoplasmsand dystrophy as described in women (Dallenbach-Hellweg,
Unequalendometrial
1987).In cases of unequaldifferentiation
a partialhormone
differentiation(UED)
11
refractiveendometriumis more likely(Fig.6).
rentiationdid not occur. The teratoma and the benign
serous cystadenoma did not affect the endometrialdifferentiation,Differenttypes of non tumoroussovariandystrophies(Tab.1) resultin variousfeaturesof IEDtoo.
lrregularendometrial
differentiation(lED)
(partially)
hormonerefractive
- proliferative
'13
- secrercry
19
- comptetety irregutitr
11
z
1
endometrial
maldifferentiation
5
n
I
i rreg u l ar
endometri al
d i ff ere nt i ati on
IE D
In the cases where a second biopsy after ovariectomywas
availableafter2 to 5 weeks (n=10)a distincttendencyto a
more regularendometrialdifferentiation
was obvious,interpreted as indicativefor a possiblereversibility
of these hormonallymediatedalterationsof functionalendometrialmorp h o l o gy .
-t
ortemporary
I permanent
i
problems
fertility
I
I
Fig. 6:
C l i n i c als ignif ic anc e
Equine endometrialfunctionaldisturbancesare first described by our group as a phenomenonoccurringspontaneously(Schoonet al., 1998)or in the course of hormonal
active ovarian neoplasms(BarTmannet al., 1998).The diagnosis is possible by the investigationof routinelyH.-E.stained slides and confirmed by immunohistological
methods, In all cases investigated
at leastone and mostlyall of
parametersdiffer from normal exthe immunohistological
pressionpatterns.
The endometrialdifferentiation
is a highlysensitiveindicator
of the hypothalamo-pituitary-ovarian-endometrial
axis, A
physiological
equine estrouscycle resultsin a uniformand
synchronousfunctional morphology of the endometrium
(Brunckhorstet al., 1991;Strankmeyer, 1993; Raila et al.,
1997) Disordersmay lead to permanentor temporarysubfertilitypossiblydue to an altereduterineenvironment,e.g,
in a disturbed uterine secretory protein pattern as described in endometrosis(Baderet al., 1997).Whilethese alterationshave been well known in human gynecopathology
for years and describedin detail indicatinga ,,specific"ae-
558
hormonal
disturbances
Causes and featuresof endometrialmaldifferentiation.
Ursachenund Erscheinungsformen
Fehlendometrialer
differenzierunqen.
No conclusivestatementregardingthe aetiopathogenesis
can be made in cases where ovarian disorders have been
excluded.The conditionis relatedneitherto age nor to parity of the mare nor to the annual season. Most of the
mares have been barren for one or severalyears,The latter
fact indeedindicatesthat endometrialmaldifferentiation
is a
diagnosisof clinicalimportancewhich shouldbe includedin
the assessmentof endometrialbiopsy diagnosis.More detailed case control studies includingthe estimationof the
endocrinestatus are necessaryfor the understandingand
prognosticassessmentof this lesion.The aim of our current work is to correlate classicalhistopothologicalmethods, immunohistopathology
and clinicalsymptoms including endocrinologyto infer a causal therapeuticconcept
from a certainfeatureof endometrialmaldifferentiation.
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Stuten. Hannover,Tierärztliche
Hochschule,Dissertation
Prof. Dr. H.-A. Schoon
Dr. Doris Schoon
lsabellWiegandt
Dr. HeikeAupperle
In stitut für Veterinär-Pathologie
An den Tierkliniken33
04301 Leipzig
Tel.0341/9738270
Fax. 0341/9738299
[email protected]
Dr. Claus Peter Barlmann
Klinik für Pferde
Tierärztliche Hoch schule Hannover
BischofsholerDamm 15
D-30173 Hannover
Tel.:0511-8567233
Fax:0511-8567688
559