厚生連医誌

第１３巻

１号 ８１〜８８ ２００４Case report

Two cases of pseudo―partial mole of placenta
Department of Pathology, Pathology Center ; Pathologist １），Department of Genetic diagnosis（Chu―etsu
genetic diagnosis study group）；Clinical technologist ２）

Toshihiko Ikarashi １），Hidehiro Hasegawa ２）

chopulmonary dysplasia of IV stage, apnea attack, retinopathy of prematurity of III stage, cardiac hypertrophy, anddilatation of cerebral ventricles. The placenta weighed
５００g（normal range＝１４０±３０g）and the ratio against fetal weight reached ０．
８５（normal range＝０．
２７）．Placenta
was half replaced by vesicular chorionic villi, reached up
to ２x１cm in diameter. Vesicular villi dispersedly intermingled with normal villi in whole placenta, which neglected multiple pregnancies. Chorionic stem villi weremicroscopically swollen with central cistern formation but
no chorionic epithelial proliferation and atypism werefound. Based on the diagnosis of partial mole, she wastreated with intrauterine curettage and urine b―humanchorionic gonadotropin（HCG）had come down into normal range for ８ months after delivery. Basal body temperature（BBT）became biphasic and no silhouette wasfound in chest radiograph. Fluorescent in situ hybridization（FISH）for formalin―fixed paraffin―embedded specimens with anti―centromeres for both X―（red spot）and
Y―chromosome（green spot）revealed that there were１１
３ cells with ２ red spots（diploid pattern of ４６，XX，９７％）and ４ cells of ３ red spots（triploid pattern of６９，XXX, including X trisomy pattern，３％，Table１）（３，４）．In spite of a chromosomal mosaicism, the previous diagnosis of partial mole was corrected as pseudo―
partial mole on the basis of diploid pattern.

Background : Though pseudo―partial mole was not a
gestational trophoblastic disease, it was frequently treatedas partial mole. In a meaning to avoid a useless treatment, the spread and the establishment of diagnosis of thisdisease were recommended. Cases : Two cases withpseudo―partial mole of placenta in mid―and late trimesters
were reported. Each placenta was very heavy in spite of
appropriate―for―gestational―aged female babies. Placental
stem villous hydrops was pathognomonic and each placenta revealed diploid pattern of ４６，
XX by fluorescencein situ hybridization（FISH）．Our cases were diagnosed
as pseudo―partial mole because of a genetically diploid
pattern, a pregnancy sustained until mid―trimester, and a
defect of chorionic epithelial proliferation. Conclusion :FISH was very effective method to confirm pseudo―partial mole as to omit an unnecessary treatment against gestational trophoblastic disease.
Key words : pseudo―partial mole, placental stem villous
hydrops, mesenchymal dysplasia of placenta, chorioangioma, diploid, fluorescence in situ hybridization（FISH）
Case report
９，１０，Table１）．
Case１（Fig．
１―４，
A ３０―year―old mother with neurofibromatosis（Recklinghausen's disease）admitted because of premature rupture of membranes and a female baby was delivered transvaginally at ２
３ weeks of gestation in １
９９０． Neonate
weighed ５９０g（appropriate for gestational age）and had
a minor anomaly of right―sided iris defect. She gained anormal weight increment but was complicated with bron-Case２（Fig．
５―１０，Table１）
A ２
９―year―old mother delivered female baby，
２０６５g（small―for―date），Apgar ９，at ３
７ weeks of gestation in
２００２．Placenta weighed ９３０g and revealed solid hydropic

Table１．FISH results for X―and Y―centromeres
Case

１examined nuclei
total numbers
１８５％
２８６２％

X
６８３７％
１４０４９％

results
XX
１１３
６３％
９７％
１４２５１％
９７％― 81 ―

XXX
４３％
４３％

Two cases of pseudo―partial mole of placenta

villi, reached up to ５mm in diameter and occupied morethan half volume of placenta. Vesicular villi dispersedlyintermingled with normal villi in whole placenta, which
neglected multiple pregnancies. Stem villous hydropicchange accompanied hypovascular change. Thrombosis
and vasculitis were found. There was a small chorioangioma up to １．
５cm in diameter. There was a weak tendency in cistern formation but no trophoblastic epithelial
proliferation and atypism could be found. Fluorescent insitu hybridization（FISH）for formalin―fixed paraffin―embedded specimens with anti―centromeres for both X―（redspot）and Y―chromosome（green spot）revealed that there
were １４２cells with ２ red spots（diploid pattern of ４６，XX，９７％）and ４ cells of ３ red spots（triploid patternof ６９， XXX, including X trisomy pattern，３％）（３，４）．In spite of a chromosomal mosaicism, the diploid
pattern indicated pseudo―partial mole. It was diagnosed as
pseudo―partial mole of placenta with chorangioma by
Masahiro Nakayama, a pathologist in Osaka Medical Center and Research Institute for Maternal and Child Health,on the mail consultation of the Japanese Society of Pathology.
Discussion
Differential diagnosis consisted of gestational trophoblastic diseases : partial mole and total mole（Table２）（１―３）．A gestational duration of pseudo―partial
mole was longer than those of moles, i.e. occurred more
often in second trimester than in first trimester. Pseudo―
partial mole and total mole were genetically diploid but
partial mole was triploid. Moles showed trophoblastic epithelial proliferation with atypism. Both pseudo―partial
mole and partial mole had evidence of fetus, i.e. nucleatederythrocytes, but total mole lacked it. As to hydropic villous changes in early abortion before an establishment ofhematopoiesis evidence of nucleated erythrocytes was notavailable for reconfirmation of fetus, which required genetic analysis for objective diagnostic criteria.
Paradinas reviewed the pathognomonic mechanism ofpseudo―partial moles as follows!：half cases of pseudo―
partial moles tended to complicate Beckwith―Wiedemannsyndrome, which complicated overgrowth of both fetus,
including omphalocele with or without macrosomia, andplacenta because of up―regulation of genes by deregulation of the normal expression of imprinted genes. Normally in chromosome１
１p the gene of insulin―like growth
factor II（IGF２）as a cell―cycle accelerator was activatedonly in paternal allele and the gene of p５
７Kip２ as a cell―cycle repressor was activated only in maternal allele, i.e.
imprinted. Conversely in the case of Beckwith―Wiedemann syndrome IGF２ was up―regulated and p５７Kip２
was down―regulated because the imprinted suppression inmaternal allele were replaced by paternal one or there
were two paternal copies of these regions. Pseudo―partial
moles without Beckwith―Wiedemann syndrome had apossibility of minute abnormality at a gene level because
we could not reveal triploid by usual FISH chromosomal
examination. Genetic rearrangement analysis should bedone with single―stranded conformation polymorphism（SSCP）or restriction fragment length polymorphism（RFLP）after polymerase chain reaction（PCR）．
References
１．Ohyama M et al. Mesenchymal dysplasia of the placenta. Pathology
International ２０００；５０：７
５９―６４．
（Their case reportand discussion with ３２ cases listed from journal references）
２．Paradinas FJ et al. Pseudo―partial moles : placental
stem vessel hydrops and the association with Beckwith―Wiedemann syndrome and complete moles.
４．
（Database analyHistopathology ２００１；３
９：４
４７―５
sis at the Trophoblastic Disease Unit at Charing
Cross Hospital, London，
１５cases were listed and discussed the genetic pathogenesis．
）
３． Gestational trophoblastic disease , FISH . In :Ikarashi's medical ABC understandable even by a cat―Clinicopathological mechanism and its medical
３８th ed. Nagaoka : Pimento
strategy―．Ikarashi T. ed．
Press；２００３（３３．
０GB of content）（Soft : Windows.
Exel, PowerPoint（Microsoft），Photoshop（Adobe），Ichitaroh（Justsystem），and DocuWorks Desk（FujiXerox））．
４．Mnaual of genetic pathological diagnosis with formalin―fixed and paraffin―embedded specimens. Ver．
２．
eds Genetic examination room in Pathology Centerof Niigata Pref. Health Association, and Chuetus genetic diagnosis study group. Nagaoka．
２００３（．CD―R
available from : URL : http : / / www . Niigata ―kouseiren . jp / hospital / byouri ２ ／ site ％２０one / top .
htm）．

和 文 抄録偽部分奇胎の２症例
病理センター、病理科；病理医 １）、遺伝子診断室（中越遺伝子診断研究会）；臨床検査技師 ２）
五十嵐俊彦 １）、長谷川秀浩 ２）
背景：絨毛性疾患でない偽部分奇胎が部分奇胎として治療されている。無用な治療を避ける意味で、偽部分奇胎の疾患概念の普及と診断確立が望まれている。
症例：妊娠中期と後期まで妊娠が継続した偽部分奇胎の２症例を経験したので報告した。各症例の出生時女児体重は正常範囲で Beckwith―Wiedemann 症候群は認められなかった。胎盤は重く、びまん性・散在性に胎盤全体に水腫様幹絨毛が認められた。胎盤絨毛の染色体は fluorescence in situ hybridization（FISH）検査上、二倍体の４６，XX と判断された。顕微鏡所見上、絨毛上皮細胞の増生と異型性は認められなかった。以上より、本症例は偽部分奇胎（別称：胎盤幹血管水腫、胎盤間葉異形成など）と診断された。結論：妊娠早期における奇胎からの偽部分奇胎の組織学的診断は困難な場合が多く、FISH による染色体検査は 補助診断として極めて有効であった。
キーワード：偽部分奇胎、胎盤幹血管水腫、胎盤間葉異形成、絨毛血管腫、二倍体、蛍光 ISH（FISH）― 82 ―

molarcomplete― 83 ―
possible

−

−

−＋＋＋＋

stem villous
hydropsstem villous
aneurysmal
dilatation
stem villous
peripheral
chorioangiomatoid
extramedullary hematopoiesis

＋

−＋＋

weak

terminal villous
hydropsterminal villous cistern
−＋＋

villi

trophoblastic inclusion＋, diffusep５
７ （ kip２）−−−

possible＋＋＋−／weak,focal, mini- variablemal
marked
−
often

−

−

round

scalloped

scalloped

embryovillous outline
trophoblast
proliferation
trophoblastic atypism

diploid
triploid
６XX ，４６
６
９XXY（ di- ４andry ） ＝ XY（ diandry ）＝ disdispermy
３（２３X ＋２
３ permy（ ２３Y）＋Y）＋egg（２３ X，２empty egg
X）pseudo − partial
partilal molemole

３rd＜２nd １st trimes- １st trimesterter＜１sttrimester＋＋−

syncytiotrophoblastpresentation

implantation chorionic ― cytotrotype
phoblast
site

diploidvilloustrophoblastic diseasemolar

non−trophoblastic

trophoblastic

histology−−−

possible＋＋＋invasive−after molechoriocarcinoma

nonmolar−−missedabortion

implantation site IT in anchoring fociexaggerated placentalsite
troplacental
phoblastic
site
tumor

−−

spottingchorionic − type IT in
laeve
placental
epithelioidsite nodule
trophoblastic tumor

第１３巻

developmental genetics

classification

厚生連医誌
１号 ８１〜８８ ２００４Table２．Clinico―pathological differential diagnosis for gestational trophoblastic diseases.

― 84 ―
２−２２＋−／＋−／＋+++

++++
−／＋＋
toward distal end

HPL

Mel−CAM, −／＋＋＋ ++++
CD１
４６＋ toward
distal end

PlAPchemotherapy effecttreatment

Ki−６７ in- ９０％＜
dex−＋−０−

３−１０％

２５−５０％

−−−

０−

−++++

hysterectomy

chemotheray

１０％＜−／＋＋variable＜１％−／＋＋＋＋＋＜１０％+/++−／focal−／focal＋＋hysterectomy

variable

１０−２０％+/++−／focal−／focal＋＋−+ + + + in + + + + ineosinophilic eosinophilic
cytoplasm
cytoplasm

１−１０＋−＋++

expansileepithelioid
nest or cord
or
solid
mass

monomorphic
IT ,small,round, uniform,
eosinophilicor clearchorionic − type IT in
laeve
placental
epithelioidsite nodule
trophoblastic tumor+ in multi- −nucleated IT++++

０−６

good

９０％＜単核−+ in IT+ in IT＋−−+ in ST

CK−１８++++

inhibin−a−−b−HCG−−， ＋in multinucleated IT

++++

HLA−G

++++

＋−

fibrinoid

mitosis ／１０HPF+ in IT

from periphery to lumen

from lumen
to periphery

vascular invasion−−

infiltrating
single cellor confluent
cells

implantation site IT in anchoring fociexaggerated placental
site
troplacental
phoblastic
site
tumor
monomordimorphic :phicIT ,primitive
large, pleoprevillous −morphic,type
troabundant ,phoblasticeosinophilic

choriocarcinoma

nonmolar−completeinvasive

++

−

molar

pseudo − partial
partilal mole

molecalcification+++ eosino- −philic cytoplasm

syncytiotrophoblast

necrosis++++

implantation chorionic ― cytotrotype
phoblast
site

expansile ,dimorphic

villoustrophoblastic diseasemolar

non−trophoblastic

trophoblastic

histology

infiltrationcellclassification

Two cases of pseudo―partial mole of placenta厚生連医誌

第１３巻

１号 ８１〜８
８ ２００４Fig１．Case１．Enlarged placenta consisted of normal villi intermingled with vesicular ones, thelatter of which occupied around half volumeof placenta. Vesicular diameter reached up to
１cm in close―up picture.

Fig２．Case１．Stem villous hydropic change and cistern formation on scanningmicroscopy, graduated in millimeters.

Fig３．Case１．Stem villous hydropic change without any trophoblastic epithelial
proliferation and atypism, scaled ２mm in length.

― 85 ―

Two cases of pseudo―partial mole of placenta

Fig４．Case１．Most chorionic cells had two red spots in FISH.

Fig５．Case２．Enlarged placenta consisted of normal villi intermingled with vesicular ones, the latter of which
occupied more than half volume of placenta.

― 86 ―

厚生連医誌

第１３巻

１号 ８１〜８８ ２００４

Fig６．Case２．Stem villous hydropic change withhypovascular change. Thrombosis（arrow）
and vasculitis（arrow head）were found,graduated in millimeters or bar of ２mm inlength.

Fig７．Case２．Stem villous hydropic change was confirmedwith hypovascular change and cistern formation without
any trophoblastic epithelial proliferation and atypism,
scaled ２mm in length. Chorangioma was found in theleft picture.

― 87 ―

Two cases of pseudo―partial mole of placenta

Fig８．Case２．Most chorionic cells had two red spots in FISH.

Fig９．Fetal weight of pseudo―partial mole from reference, which was limited within normal range.
Closed circle（●）was complicated with Beckwith―Wiedemann syndrome and open circle（○）was
free from this syndrome!．There was no significant difference between them. Our Case１（▽）
and Case２（△）were also drawn.

Fig１
０．Placental weight of reported cases was very
heavy!．Symbol marks were same as above andno statistical difference was found.

― 88 ―