Pathology of Pathology of

Gestational Gestational

Trophoblastic DiseaseTrophoblastic Disease

Modified WHO classification of GTDModified WHO classification of GTD

�� Molar lesionsMolar lesions�� Hydatidiform moleHydatidiform mole

�� CHMCHM

�� PHMPHM

�� Invasive moleInvasive mole

�� Non molar lesionsNon molar lesions�� ChoriocarcinomaChoriocarcinoma

�� Placental site trophoblastic tumor (PSTT)Placental site trophoblastic tumor (PSTT)

�� Epithelioid trophoblastic tumor (ETT)Epithelioid trophoblastic tumor (ETT)

�� MiscellaneousMiscellaneous trophoblastictrophoblastic lesionslesions�� Exaggerated placental siteExaggerated placental site

�� Placental site nodulePlacental site nodule

Normal Normal

pregnancypregnancyPHMPHM CHMCHM

10%10% 90%90%

PloidyPloidy 2N2N 3N3N 2N2N 2N2N

ChromosomeChromosome 46XX46XX

46XY46XY

69XXY 69XXY (70%)(70%)

69XXX 69XXX (27%)(27%)

69XYY 69XYY (3%)(3%)

46XX 46XX (89(89--97%)97%)

46XY 46XY (7(7--13%)13%)

No 46 YYNo 46 YY

ParentalityParentality BiparentalBiparental Biparental Biparental

DiandricDiandricPaternal Paternal

DiandricDiandric

Molar pregnancy

Pathology of CHMPathology of CHM

Macro : Vesicles, maximal diameter 2 cm.Macro : Vesicles, maximal diameter 2 cm.

Pathology of CHMPathology of CHM

�� MicroMicro

�� Enlarged villi, cavitation (necrosis)Enlarged villi, cavitation (necrosis)

�� Trophoblastic proliferation around villi Trophoblastic proliferation around villi with minimal atypiawith minimal atypia

�� Absence or paucity of fetal stromal BVsAbsence or paucity of fetal stromal BVs

�� Atypia of ITs atAtypia of ITs at decidual implantation decidual implantation site.site.

Large swollen villi Central cistern

CHM

CHMCHM

Concentric CT & ST hyperplasia Atypical implantation site

�� In the 1960s mean GA of CHM = 17 wksIn the 1960s mean GA of CHM = 17 wks

�� Nowadays = 9.4 wksNowadays = 9.4 wks

�� Common error is diagnosis of early CHM Common error is diagnosis of early CHM

as PHMas PHM

�� MacroMacro

�� Resemble abortus with some vesiclesResemble abortus with some vesicles

Pathology of early CHMPathology of early CHM Early CHMEarly CHM

�� MicroMicro�� Slight enlargement with Slight enlargement with scattered scattered cavitiescavities in villiin villi

�� Typical villous morphology : Typical villous morphology : cauliflower cauliflower likelike (lobulated appearance)(lobulated appearance)

�� Focal to diffuse trophoblastic atypiaFocal to diffuse trophoblastic atypia�� Villous stromaVillous stroma

�� HypercellularHypercellular (stellate mesenchymal cells in blue (stellate mesenchymal cells in blue myxoid matrix) = fibroadenoma likemyxoid matrix) = fibroadenoma like

�� Prominent karyorrhexis in villous mesnchymal Prominent karyorrhexis in villous mesnchymal cells, cells, stromal nuclear debrisstromal nuclear debris

�� Numerous vessels Numerous vessels with nucleated RBCswith nucleated RBCs

Early CHMEarly CHM

Typical features in early CHMTypical features in early CHM�� Abnormally shaped villi Abnormally shaped villi (bullous or (bullous or polypoid)polypoid)

�� Stromal mucinStromal mucin�� Stromal nuclear debrisStromal nuclear debris (resulted (resulted of increased stromal proloferation of increased stromal proloferation and apoptosisand apoptosis

•Moderate villous enlargement•Not prominent cistern•Concentric trophoblastic •hyperplasia

Hypercellular stromaBluish appearance

Irregular villous contours “knuckles or toes” Atypical implantation site

Early CHM

MacroMacro

••Vesicle appearance (partial change) vary to GAVesicle appearance (partial change) vary to GA

••Presence of fetus (more often malformed) or fetal partPresence of fetus (more often malformed) or fetal part

PHM

CHM

Pathology of PHMPathology of PHM

�� MicroMicro�� Two population of villiTwo population of villi

�� Smaller fibrotic normal appearing villiSmaller fibrotic normal appearing villi�� Larger irregular shaped hydropic villiLarger irregular shaped hydropic villi

�� Central cisternsCentral cisterns�� Irregular scalloped borderIrregular scalloped border (Norwegian fjord type , (Norwegian fjord type , sharp angulated) sharp angulated)

�� Invagination of trophoblast and Invagination of trophoblast and round inclusionsround inclusions(solid or cystic)(solid or cystic)

�� Evidence of fetal developmentEvidence of fetal development : No : No fetal tissue does not rule out PHM.fetal tissue does not rule out PHM.

�� Late PHMLate PHM……..Angiomatoid malformationAngiomatoid malformationSyndactyly

Mixed population of vliil Mild ST proliferation

Coexisting fetal tissue PHM

Cistern &scalloped villi

Mixed population of vliil Angiomatoid change

PHM

Round inclusions

Pathological mimics of PHMPathological mimics of PHM

�� Early CHMEarly CHM

�� Hydropic spontaneous miscarriageHydropic spontaneous miscarriage

�� Twin gestation with CHM and existing Twin gestation with CHM and existing

fetusfetus

�� Placental angiomatous malformationPlacental angiomatous malformation

FeaturesFeatures CHMCHM PHMPHM Hydropic Hydropic

abortusabortus

VilliVilli Hydropic & Hydropic &

cisternscisternsFocal hydropic, Focal hydropic,

double population double population

villivilli

Mild, seldom Mild, seldom

cisterns, very cisterns, very

rare large villirare large villi

Villous Villous

outlinesoutlines

��Rather smoothRather smooth

��Polypoid in early Polypoid in early

CHMCHM

Scalloped Scalloped

Villous Villous

inclusioninclusionIrregularIrregular, cystic , cystic

or solidor solidRoundRound, cystic or , cystic or

solidsolid

Villous Villous

stromastroma

Early CHM : Early CHM :

nuclear debris nuclear debris Nuclear debris Nuclear debris seen around VSSsseen around VSSs

Nuclear debris in Nuclear debris in

VSS wall or VSS wall or

lumenslumens

(occurring after (occurring after

embryonic embryonic

demise)demise)

FeaturesFeatures CHMCHM PHMPHM Hydropic Hydropic

abortusabortus

Villous Villous

VSSsVSSs

��Presence in early Presence in early

CHMCHM

��Absence in late Absence in late CHMCHM

Angiomatoid Angiomatoid malformation in malformation in late PHMlate PHM

PresencePresence

TrophoblastsTrophoblasts ��Multifocal or Multifocal or circumferentialcircumferential

��Significant Significant nuclear atypia at nuclear atypia at implantation siteimplantation site

��<7 % of cases <7 % of cases

show proliferationshow proliferation

��Multifocal > Multifocal > circumferentialcircumferential

��No sig atypiaNo sig atypia

��Presence in Presence in

early gestationearly gestation

��Polar or Polar or intervillousintervillous

��No sig. atypiaNo sig. atypia

Embryonic Embryonic

tissuetissue

AbsentAbsent Present, malformed Present, malformed fetus, IUGRfetus, IUGR

Often lostOften lost

KaryotypeKaryotype 46XX, Uniparental46XX, Uniparental Generally triploid, Generally triploid, biparentalbiparental

BiparentalBiparental

Genetics abnormality in PHMGenetics abnormality in PHM

�� 1% of conceptus = triploidy1% of conceptus = triploidy

�� TriploidyTriploidy 80% diandric80% diandric PHMPHM

20% digyny20% digyny Non molarNon molar

�� Most of PHMs are triploidMost of PHMs are triploid

�� Reported teraploid (> 1 paternal set of Reported teraploid (> 1 paternal set of

chromosome)chromosome)

Special investigation in Dx of Special investigation in Dx of

molar pregnancymolar pregnancy

ImmunohistochemistryImmunohistochemistry�� P57P57kip2kip2 (maternally expressed imprinted (maternally expressed imprinted

gene):gene): CHM VS non CHMCHM VS non CHM

Ploidy analysisPloidy analysis�� Triploid Triploid PHM VS non PHMPHM VS non PHM

Interphase cytogeneticsInterphase cytogenetics�� Identify chromosome aberrations by in situ Identify chromosome aberrations by in situ

hybridization (ISH) using chromosome hybridization (ISH) using chromosome specific probes (chromosome 1, X, Y)specific probes (chromosome 1, X, Y)

P57P57kip2 kip2 oror IPL/PHLDA2IPL/PHLDA2

�� Located at Located at chromosome 11p15.5chromosome 11p15.5�� Strongly Strongly paternally imprintedpaternally imprinted, being , being expressed predominantlyexpressed predominantly from maternal allele from maternal allele

�� Potent cell cycle inhibitor and tumor Potent cell cycle inhibitor and tumor suppressorsuppressor

�� lack of lts activity can lead to loss of cell cycle lack of lts activity can lead to loss of cell cycle control and hyperproliferationcontrol and hyperproliferation

�� Normal pregnancy and PHM : positive at nuclei Normal pregnancy and PHM : positive at nuclei of villous stroma, villous CT, decidual and of villous stroma, villous CT, decidual and extravillous trophoblastextravillous trophoblast

�� CHM : negative at nuclei of villous stroma, CHM : negative at nuclei of villous stroma, villous CTvillous CT

Normal villous Hydropic villous

PHM CHM

P57P57kip2kip2

P57P57kip2kip2 expressionexpression

TissueTissue Villous Villous

mesenchymemesenchymeCTCT STST IVT*IVT* DeciduaDecidua

Normal Normal

placentaplacenta

(all GA)(all GA)

++ ++ -- ++ ++

Hydropic Hydropic

degenerationdegeneration++ ++ -- ++ ++

CHMCHM -- -- -- ++ ++

PHM(both PHM(both

hydropic and hydropic and

normal villi)normal villi)

++ ++ -- ++ ++

*Intervillous trophoblast

Diego H et al, Am J Sur Pathol 2001;25(10):1225-30

PHMPHM CHMCHM Hydropic Hydropic

abortusabortus

P57P57kip2 kip2

expressionexpressionNo lossNo loss LossLoss No lossNo loss

Proliferation Proliferation

indexindex

Intermediate Intermediate

(25(25--50%)50%)High High

(50-100%)

Low to Low to

intermediate intermediate

(0(0--50%)50%)

PloidyPloidy TriploidTriploid DiploidDiploid DiploidDiploid

Markers for molar pregnancyMarkers for molar pregnancy

Pathology of invasive molePathology of invasive mole

�� Hydatidiform in which hydropic Hydatidiform in which hydropic

villi invade villi invade myometriummyometrium oror

BVs BVs or even the or even the extrauterine extrauterine sitessites

�� Dependent on extent of invasionDependent on extent of invasion

Invasive mole

GTDGTD

�� GTDs are distinct from other tumors in the GTDs are distinct from other tumors in the human body in that they are genetically or human body in that they are genetically or allograft in the motherallograft in the mother’’s bodys body..

�� They are They are fetal tumorsfetal tumors that are arising in that are arising in the motherthe mother’’s body.s body.

�� The The remarkable curabilityremarkable curability of GTDs with of GTDs with chemoRx might reflect the underlying chemoRx might reflect the underlying immune response of the mother to paternal immune response of the mother to paternal antigens expressed on the surface of antigens expressed on the surface of trophoblastic cells.trophoblastic cells.

Int J Gynecol Cancer 2006;16:1500Int J Gynecol Cancer 2006;16:1500--1515

Trophoblast

Villous Nonvillousor

ExtravillousCT

STIT•First trimester•Developingcytotrophoblastic column

Proliferation and differentiation of CT of anchoring CV

Migrate as cell columns in first few wks of pregnancy to invade decidua

TrophoblastsTrophoblasts

�� Trophoblastic differentiation at 7 days Trophoblastic differentiation at 7 days blastocystblastocyst

�� TypeType�� Villous Villous CTCT

IT(small amount)IT(small amount)

STST

�� ExtravillousExtravillous ITIT

ST(small amount)ST(small amount)

Vacuolated TrophoblastVacuolated Trophoblast at at chorion in late pregnancy chorion in late pregnancy (described by Yeh 1989)(described by Yeh 1989)

Trophoblastic tumor differentiationTrophoblastic tumor differentiation

CTCT ChoriocarcinomaChoriocarcinoma

STST PSTTPSTT

Implantation site ITImplantation site IT Exaggerated placental Exaggerated placental

site site

Vacuolated T Vacuolated T ETTETT

Placental site nodulePlacental site nodule

Trophoblastic cellsTrophoblastic cellsFeaturesFeatures CTCT STST ITIT

Cell sizeCell size Small Small

polyhedralpolyhedralLargeLarge Medium polyhedral Medium polyhedral

to spindleto spindle

CytoplasmCytoplasm Clear, Clear,

distinct cell distinct cell

borderborder

��Amphophilic or Amphophilic or

eosinophiliceosinophilic

��Filmly to coarsely Filmly to coarsely

vacuolated (irregular vacuolated (irregular

lacy pattern)lacy pattern)

EosinophilicEosinophilic

NucleusNucleus Single, Single,

vesicularvesicularSmall, Small,

hyperchromatichyperchromaticSingle, bi, multiSingle, bi, multi--

nucleation at nucleation at

placental siteplacental site

MitosisMitosis ++ -- ++

LocationLocation Inner layer Inner layer

of villi of villi

coveringcovering

Outer layer of villi Outer layer of villi

coveringcovering��Sit in fibrin materialSit in fibrin material

��Within endoWithin endo--

myometriummyometrium

��In walls or lumens In walls or lumens

of spiral arteriolesof spiral arterioles

CT & ST hCG

Impantation site IT Epithelioid IT

Hormone productionHormone production

TrophoblastTrophoblast hCGhCG hPLhPL PLAPPLAP InhibinInhibin CytokeratinCytokeratin P63P63

CTCT -- -- -- ++ ++

∆∆N N

isoformisoform

STST ++++++ ++ ++

ITIT ++ focalfocal ++++ ++ ++

Vacuolated Vacuolated

ITIT++ ++++ ++ + +

TA TA

isoformisoform

+++ +

++

Pathology of ChoriocarcinomaPathology of Choriocarcinoma

Macro : Well circumscribed nodular lesion with Macro : Well circumscribed nodular lesion with

dominantly hemorrhagic structuredominantly hemorrhagic structure

Pathology of ChoriocarcinomaPathology of Choriocarcinoma

MicroMicro�� No chorionic villiNo chorionic villi�� Peripheral trophoblasts (lack intrinsic Peripheral trophoblasts (lack intrinsic tumor vasculatures)tumor vasculatures)

�� BiBi--laminar patternlaminar pattern (recapitulates (recapitulates trophoblast of early implanting trophoblast of early implanting blastocyst)blastocyst)

�� Extensive myometrial invasion Extensive myometrial invasion without destruction or necrosis of without destruction or necrosis of myometriummyometrium

�� Tumor in dilated vascular sinusesTumor in dilated vascular sinuses

Choriocarcinoma

Biphasic trophoblasts

Choriocarcinoma

Marked trophoblastic atypia

Hemorrhagic necrosis

Special studySpecial study of choriocarcinomaof choriocarcinoma

�� ImmunohistochemistryImmunohistochemistry�� UsefulUseful

�� Positive Positive �� hCGhCG (sig +ve), (sig +ve), CK, EMA, CEA, Ki67, hPLCK, EMA, CEA, Ki67, hPL(fewer cells), (fewer cells), PLAPPLAP (rare)(rare)

�� Genetic polymorphismsGenetic polymorphisms�� DDX gestation or non gestational DDX gestation or non gestational choriocarcinomachoriocarcinoma

�� To define prognosis and influencing therapeutic To define prognosis and influencing therapeutic decisiondecision

�� To understand biology of trophoblastic tumorTo understand biology of trophoblastic tumor

Pathology of PSTTPathology of PSTT

MacroMacro

�� Variable appearanceVariable appearance

�� IlledIlled--defined massdefined mass

��Well circumscribed noduleWell circumscribed nodule

�� In myometrium with or without In myometrium with or without

projection into endometrial cavityprojection into endometrial cavity

�� No striking hemorrhage or necrosisNo striking hemorrhage or necrosis

MicroMicro�� Recapitulate appearance seen at placental bedRecapitulate appearance seen at placental bed

�� Diffuse infiltration of mononuclear and multinuclear IT Diffuse infiltration of mononuclear and multinuclear IT arranged in cords, islands, sheets between arranged in cords, islands, sheets between myometrial bundlesmyometrial bundles

�� Vascular invasion recapitulates normal implantation Vascular invasion recapitulates normal implantation site : cell migrate through and replace vessel walls , site : cell migrate through and replace vessel walls , maintaining overall vascular architecturemaintaining overall vascular architecture

�� Less intravascular proliferationLess intravascular proliferation

�� Vary mitotic activityVary mitotic activity

�� Abundant extracellular eosinophilic fibrinoid materialAbundant extracellular eosinophilic fibrinoid material

Pathology of PSTTPathology of PSTT

PSTT

Sheets of atypical IT ITs dissecting through muscle fibers

PSTT

extracellular eosinophilic fibrinoid material

mononuclear and multinclear IT

Pathology of ETTPathology of ETTProposed by Mazur in 1989Proposed by Mazur in 1989

MacroMacro��Nodular expansile patternNodular expansile pattern

��50% of cases arise in lower 50% of cases arise in lower uterine segment or uterine segment or endocervixendocervix

Pathology of ETTPathology of ETT

MicroMicro�� Mixture of mononuclear cells with eosinophilic Mixture of mononuclear cells with eosinophilic or clear cytoplasm forming nests or cordsor clear cytoplasm forming nests or cords

�� Areas of hyalinization or eosinophilic debris Areas of hyalinization or eosinophilic debris simulating tumor cell necrosis at center of simulating tumor cell necrosis at center of tumor nests (resembling keratin material in tumor nests (resembling keratin material in SCC)SCC)

�� Characteristic geographic patternCharacteristic geographic pattern

�� Dysmorphic calcification in areas of necrosisDysmorphic calcification in areas of necrosis

�� Low mitotic activityLow mitotic activity

ETT

Nodular expansile pattern

Mononuclear cells with eosinophilic cytoplasm forming nests or cords

P63

Areas of hyalinization or eosinophilic debris

ETT

PSTT v.s. ETT and choriocarcinomaFeature PSTT ETT Choriocarcinoma

Cellular population

Monomorphic ;

implantation site ITMonomorphic ;

chorionic -type IT

Dimorphic ; primitive previllous -type trophoblast

Cell size and shape

Large and pleomorphic

Small round and uniform

Irregular , highly variable

Cytoplasm Abundant and eosinophilic

Eosinophilic or clear Eosinophilic to purple

Growth Pattern Infiltrating single cells or confluent sheets

Epithelioid nests or cords or solid masses

Dimorphic ; mononucleate trophoblast and ST

Margin Infiltrating Circumscribed Circumscribed , expansile

Hemorrhage Focal or haphazard Usually present Massive and cent ral

Cellular necrosis Usually Absent Extensive Extensive

Calcification Absent Usually present Absent

Vascular invasion

From periphery to lumen

Absent From lumen to periphery

Fibrinoid change Present Present Absent

Mitosis Variable ;0-6/10HPF

Variable ;1-10/10HPF

High ;2-22/10 HPF

Clinical features of PSTT , ETT and choriocarcinoma

Feature PSTT ETT Choriocarcinoma

Clinical Presentation

Missed Abortion Abnormal vaginal bleeding

Persistent GTD after HM

Last Pregnancy or GTD

Variable , can be remote

Variable , can be remote

months

History of mole 5-8% 14% 50%

Serum hCG Low (< 100-2,000IU/L)

Low (50 – 500IU/mL )

High (>10,000IU/mL )

Behavior Variable Variable Aggressive if untreated

Response to chemotherapy

Variable Variable Good

Treatment Surgery (hysterectomy )

Surgery (hysterectomy )

Chemotherapy

Markers for trophoblastsMarkers for trophoblasts

�� hCGhCG�� hPLhPL�� Inhibin Inhibin αα

�� Shih & Kurman showed that Shih & Kurman showed that Inhibin Inhibin αα was expressed was expressed by all population of trophoblasts except CTby all population of trophoblasts except CT

�� Melanoma cell adhesion molecule (MelMelanoma cell adhesion molecule (Mel--CAM) = MUC18CAM) = MUC18�� Kurman found that MelKurman found that Mel--CAM is specific and sensitive CAM is specific and sensitive

marker for IT in normal placenta implantation site and marker for IT in normal placenta implantation site and GTD lesionGTD lesion

�� HLAHLA--GG (non classical major histocompatibility (non classical major histocompatibility class I)class I)�� Singer et al showed positivity in all GTD lesions, but Singer et al showed positivity in all GTD lesions, but

negative in non trophoblastic uterine neoplasmsnegative in non trophoblastic uterine neoplasms

Biomarkers for diagnosis GTDsBiomarkers for diagnosis GTDs

PSTTPSTT ETTETT ChorioCAChorioCA

hCGhCG focalfocal focalfocal diffusediffuse

hPLhPL diffusediffuse focalfocal Few cellsFew cells

PLAPPLAP Occasional Occasional

cellscellsfocalfocal rarerare

P63P63 -- ++ +/+/--

Ki67Ki67 >10%>10% >10%>10% >10%>10%

MelMel--CAMCAM ++ ++ focalfocal

Inhibin Inhibin αα ++ ++ focalfocal

CKCK ++ ++ ++

HLAHLA--GG ++ ++ ++

P63P63

�� Nuclear transcription factor belonging to P53 Nuclear transcription factor belonging to P53 familyfamily

�� Two major isoformsTwo major isoforms

�� CT expresses N isoformCT expresses N isoform

�� Chorionic type ITChorionic type IT expresses TA isoformexpresses TA isoform

�� Different P63 isoforms may be important in Different P63 isoforms may be important in control of trophoblastic differentiation and control of trophoblastic differentiation and placental developmentplacental development

Am J Sur Pathol 2004;28:1177Am J Sur Pathol 2004;28:1177--8383

P63 in normal villous and ETTP63 in normal villous and ETT

Normal villous ETT

HLAHLA--GG

�� Presence on all types of non villous trophoblast, Presence on all types of non villous trophoblast, but is not detected in villous CT and STbut is not detected in villous CT and ST

�� All trophoblastic tumors and tumor like All trophoblastic tumors and tumor like lesions express HLAlesions express HLA--G strongly and G strongly and diffusely diffusely

�� Vast majority of nonVast majority of non--trophoblastic tumors do not trophoblastic tumors do not express HLAexpress HLA--GG

�� Melanoma, renal cell , breast, ovarian and large Melanoma, renal cell , breast, ovarian and large cell carcinoma of lung may show focal cell carcinoma of lung may show focal expressionexpression

Practical immunohistochemistry approach to Practical immunohistochemistry approach to

diagnosis of lesions of nondiagnosis of lesions of non--villous trophoblast in villous trophoblast in

biopsy specimensbiopsy specimens

1.1. To confirm trophoblastic nature of To confirm trophoblastic nature of cellscells

�� hPL, inhibin hPL, inhibin αα, HLA, HLA--G, MelG, Mel--CAM(CD146)CAM(CD146)

�� CK (CAM5.2,AE1/AE3, CK18)CK (CAM5.2,AE1/AE3, CK18)

�� Discriminate trophoblast from CK Discriminate trophoblast from CK ––ve ve

maternal deciduamaternal decidua

2.2. To differentiate between nonTo differentiate between non--neoplastic and neoplastic trophoblastneoplastic and neoplastic trophoblast

�� IHC is of little helpIHC is of little help

�� KiKi--67 >10% in neoplastic lesions67 >10% in neoplastic lesions

33.. To differentiate neoplastic To differentiate neoplastic trophoblastic trophoblastic

cells from otherscells from others-- SCC SCC

-- Smooth muscle cell tumorSmooth muscle cell tumor

4.4. In practical terms, distinction In practical terms, distinction between PSTT and ETT is not really an between PSTT and ETT is not really an important oneimportant one

Practical immunohistochemistry approach to Practical immunohistochemistry approach to

diagnosis of lesions of nondiagnosis of lesions of non--villous trophoblast in villous trophoblast in

biopsy specimensbiopsy specimens