2009, Volume 25, Number 1, Page(s) 049-052
Tumor-like myxoid change in decidualized scar endometriosis of pregnancy: a case report and review of literature
Armağan GÜNAL1, Uğur KESKİN2, Güzin DEVECİ1, Mehmet Salih DEVECİ1, Müfit Cemal YENEN2, Murat DEDE2
1Gülhane Askeri Tıp Akademisi, Patoloji, Anabilim Dalı, ANKARA, TÜRKİYE
2Gülhane Askeri Tıp Akademisi, Kadın Hastalıkları ve Doğum Anabilim Dalı, ANKARA, TÜRKİYE
Keywords: Scar endometriosis, decidualization, myxoid change
A case of cesarean scar endometriosis with myxoid
change and decidualization in a 24 year-old pregnant is
presented. Patient in the second trimester complained
of mass in the scar tissue of previous cesarean section.
At 40th week of gestation, pregnancy was terminated
and subcutaneous mass was removed. Microscopic examination
revealed a lesion with lobular pattern and
prominent myxoid change in the stroma. Each lobule
was containing dilated cystic spaces resembling lymphatic
vessels. Also signet-ring like vacuolated cells were
present in myxoid stroma. The diagnosis was decidualized
scar endometriosis with myxoid change. However,
histological features of the lesion may cause diagnostic
confusion with benign or malignant tumors such as
myxoma, myxoid sarcomas and mucinous adenocarcinoma.
Immunohistochemical study and thus recognizing
cellular characteristics could help to prevent this
Endometriosis is the term used to describe
the presence of endometrial glands and
stroma in abnormal locations outside the uterus.
It can also arise in scar tissues either associated with previous abdominal surgery such as cesarean
section or episiotomy1
. Various histologic
changes could be seen in endometriosis such as
fibrosis, glandular hyperplasia or metaplasia,
decidual changes, atrophy, and calcification2
Myxoid change is a rare type which might be
confused with epithelial or mesenchymal neoplasms
both clinically and morphologically.
A case of decidualized scar endometriosis
with pronounced myxoid change including signet ring-like cells is presented and discussed
in the light of relevant literature.
A 24-year-old patient noticed a subcutaneous
mass during the second trimester of pregnancy
beneath her previous cesarean section
incision scar. Due to ongoing pregnancy surgical
excision was not performed. Follow-up showed
no increase in size. The subcutaneous mass,
which was not adherent to fascia was removed
at 40th week of gestation during cesarean section.
Macroscopically 3x2x2 cm circumscribed
gray-white lesion with gelatinous areas was
noted (Figure 1). Microscopically lobular pattern
separated by fibrous septa was observed.
Each lobule contained cystic spaces (Figure 2A)
lined with single layer of atrophic cells with no
cytoplasm, resembling endothelium of lymphatic
vessels. Loosely cohesive, vacuolated signet
ring-like cells embedded in myxoid stroma were also noted (Figure 2B). However, no mitotic
activity or nuclear atypia was seen.
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|Figure 2: (A) Cystic spaces resembling lymphatic vessels (HE,x40) and (B) vacuolated signet ring-like cells of the decidualized myxoid
stroma (HE,x200) are seen.
Histochemically, alcian blue test was
positive in myxoid areas and vacuolated cells
but PAS staining was negative. Immunohistochemically;
vimentin (1/100,V9, Neomarkers, Fremont,
CA, USA), S-100 (1/100, 4C4.9, Neomarkers,
Fremont, CA, USA), keratin (1/100, AE1/
AE3, Neomarkers, Fremont, CA, USA) and CD 34 (1/100, QBEnd, Neomarkers, Fremont, CA,
USA), CD 10 (1/30, Ab-2 clone 56C6, Neomarkers,
Fremont, CA, USA) stainings were performed.
Vimentin was strongly positive in vacuolated
signet ring-like cells (decidual cells),
CD10 was also focally positive in the cell
membranes of the decidualized cells, but keratin,
S-100 and CD 34 tests were negative. Atrophic
lining cells of cystic spaces were positive for
keratin (Figure 3A) and negative for CD 34
(Figure 3B). The histopathological diagnosis
was decidualized scar endometriosis with myxoid
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|Figure 3: (A) Keratin positivity for the lining cells of the cystic
spaces (endometrial glands), but negativity in vacuolated
(decidual) stromal cells and (B) CD 34 negativity for the lining
cells of the cystic spaces (endometrial glands) (x100).
Endometriosis is a common phenomenon;
defined as the presence at functioning
endometrial tissues outside the uterine corpus.
Scar endometriosis is a rare entity commonly
seen after surgery. It may also arise in noncicatrized
tissue in the umblical and inguinal regions1
. In most cases the histological features of
endometriosis are not problematic as for diagnosis.
However, fibrosis, glandular hyperplasia or
metaplasia, ossification and calcification are
known to be secondary to degenerative changes
which can also be seen along with endometriosis2
. Myxoid change in the stroma is a rare
finding which can be confused easily with
malignancies; e.g. metastatic adenocarcinoma,
pseudomyxoma peritonei of a mucinous tumor,
myxoma, myxoid liposarcoma and myxoid variant
of malignant fibrous histiocytoma.
There are few reported cases with
"myxoid change endometriosis” in the literature.
Three of them were seen in nonpregnant2,4,6 and two in pregnant patients3,5. In the
present case patient was pregnant and had a history
of cesarean section (Table 1).
Myxoid change in endometriosis could
be misinterpreted as a neoplasm, clinically and
histologically, especially during frozen section.
Hameed et al.6 and Clement et al.2
reported endometriosis with myxoid change in a
nonpregnant patient, whose frozen section examination
caused confusion with mucinous adenocarcinoma
and pseudomyxoma peritonei. Ying et al.4 also described myxoid change
associated with endometriosis in a nonpregnant
patient who had cesarean section one year ago.
Histological findings showed foci of large irregular
endometrial glands embedded in myxoid
stroma and acellular mucin pools, presenting as
Ying et al.4 hypothesized these myxoid
changes as a cyclic, hormone driven, predecidual
stroma altered during the menstrual cycle.
In case of pregnancy some authors related the
changes as a form of altered decidua. When
associated with a scar, the lesion arises as a
result of iatrogenic mechanical implantation.
Mc Cluggage5 and Nogales3 reported
cases of endometriosis with myxoid change
in pregnant patients. The presenting features in
our case were similar to the findings of Nogales
et al.3, because both of these patients developed
a mass at the scar tissue of cesarean section.
In case of Cluggage5 although patient was
pregnant, the site of endometriosis was unusually
localized in the groin. Histological findings
were similar being abundant myxoid change
with marked decidualization and calcification.
Suspicion for malignancies like soft tissue sarcoma,
mucinous adenocarcinoma and variety of
benign and malignant mesenchymal myxoid
lesions were taken into consideration. The authors
pointed out that myxoid change in this case
may be degenerative in nature and related to
pregnancy. In our case, there was no calcification.
Differential diagnosis is particulary
important during intraoperative consultation.
Myxoid stroma, vacuolated cells could cause
misinterpretation2. In this situation, recognizing
the absence of characteristic signs of
malignancy such as nuclear atypia and mitosis
prevents overdiagnosis. Histochemical and
immunohistochemical studies can be helpful for
routine interpretation. In signet ring cell carcinoma,
PAS strongly stains the cytoplasmic vacuoles whereas the decidual cells are PASnegative.
Immunohistochemically, decidual cells
are strongly vimentin positive while mucinous
carcinoma cells are not. Also keratin stains
negatively in decidua but positively in carcinoma.
In our case vimentin was strongly positive
in vacuolated (decidual) cells. CD10, as an
important marker for endometrial stroma, was
also positive in the cell membranes of the decidualized
cells, but keratin expression was negative.
As a result; although the histologic
diagnosis of endometriosis is usually easy, diagnostic
problems can occur as a result of alterations
or absence of glandular or stromal components,
or when secondary changes are present,
especially myxoid change which is rarely seen
and not very well known by pathologists. It can
be confused with neoplasm clinically and histologically.
A special care should be taken while
taking patients' obstetrical and surgical history
and examining their pathology specimens. Also
immunohistochemical and conventional histochemical
tests may also help in differential diagnosis.
1) Brenner C, Wohlgemuth S. Scar endometriosis. Surg
Gynecol Obstet 1990;170:538-540.
2) Clement PB, Ganai CO, Young RH, Scully RE.
Endometriosis with myxoid change. A case simulating
pseudomyxoma peritonei. Am J Surg Pathol
3) Nogales FF, Martin F, Linares J, Naranjo R, Concha A.
Myxoid Change in decidualized scar endometiosis
mimicking malignancy. J Cutan Pathol 1993;20:87-91
4) Ying AJ, Copeland LJ, Hameed A. Myxoid change in
nondecidualized cutaneous endometriosis resembling
malignancy. Gynecol Oncol 1998;68:301-303.
5) McCluggage WG, Kirk SJ. Pregnancy associated
endometriosis with pronounced stromal myxoid change.
J Clin Pathol 2000;53:241-242.
6) Hameed A, Jafri N, Copeland LJ, O'Toole RV.
Endometriosis with myxoid change simulating mucinous
adenocarcinoma and pseudomyxoma peritonei.
Gynecol Oncol 1996;62:317-319.