Author
Information
Kimaya Mali
(*
Assistant Professor, *** Professor, Department of Obstetrics & Gynecology,
** Associate Professor, Department of Pathology, Seth GS Medical
College & KEM Hospital , Parel, Mumbai , India
Abstract
Placental site nodule is a rare, well-circumscibed, benign,
generally asymptomatic lesion of chorionic type intermediate trophoblastic
origin, which is often detected several months to years after the pregnancy
from which it resulted. We report a case of placental site nodule which was incidentally
diagnosed on premenstrual dilatation and curettage in a
patient who presented with abnormal uterine
bleeding three years after a spontaneous abortion.
Introduction
Placental site nodule (PSN) is a benign lesion which is rare
and represents remnants of intermediate trophoblast from a previous gestation.
It generally represents a retained noninvoluted placental site. Placental site
nodule is diagnosed in many cases, years after tubal ligation which suggests
that it develops as an unrecognized pregnancy or is retained in the endometrium
for a long time. These lesions many a times are diagnosed incidentally after
curettage or in hysterectomy specimens done for abnormal uterine bleeding, post
coital bleeding or abnormal cervical smears.
Case
Report
A 38 year
old woman, married for 20 years, multipara, presented to out
patient department with
complaints of menorrhagia for 1 year. She had had 5 normal deliveries and one
spontaneous abortion. Her last pregnancy resulted in spontaneous abortion for
which curettage was done 3 years ago. She or her spouse had not undergone sterilization procedure. On examination her vital parameters were
stable. On speculum examination her cervix was hypertrophied and on bimanual
examination the uterus was anteverted, 6-8 weeks in size, and firm. Pelvic
ultrasonography showed a bulky uterus with
endometrial thickness of 10 mm and an anterior wall leiomyoma of 10x9
mm. Her Pap smear was normal. A premenstrual dilatation and curettage was performed for evaluation of
abnormal uterine bleeding. Moderate amount of endometrium was obtained which
was sent for histopathological examination. Histopathological examination
showed secretory endometrium with tortuous glands showing secretory changes. The
stroma was loose and edematous with spiral arterioles and decidualization
around them. A prominent well circumscribed nodular, eosinophilic lesion was seen. It was composed of single and nests of cells within an abundant extracellular hyaline
material. These cells were of intermediate trophoblastic origin, had
pleomorphic hyperchromatic bizarre nuclei and plenty of vacuolated eosinophilic
cytoplasm. No mitosis, decidua or chorionic villi were seen. A diagnosis of a
placental site nodule in a background of secretary endometrium was made. Her β-human chorionic gonadotropin (β-hCG)
levels were not elevated (less than 2 mIU/ml), when checked after the histological diagnosis was made..
Figure 1.
Well circumscribed eosinophilic nodule composed of intermediate trophoblastic
cells embedded in a hyalinized extracellular matrix. Endometrial glands and
stroma are seen around the nodule. (H and E × 100)
Figure 2.
Higher magnification of the nodule showing large vacuolated pleomorphic
trophoblastic cells amidst eosinophilic extracellular matrix. (H and E × 400)
Discussion
A
placental site nodule is a well circumscribed hyalinized lesion composed of
chorionic-type intermediate trophoblastic cells. Placental site nodule
represents a retained noninvoluted placental site tissue which may have
remained in the uterus for several years after the pregnancy from which it
resulted. The interval from the recent
pregnancy till the detection of tumor averages around 3 years with range of
around 1 month to 8 years.[1] Placental site nodule is seen in
endocervix in 40% of cases, 56% in endometrium and 4% in fallopian tube and very
rarely in ovary. Placental site nodule should be differentiated from other
lesions like placental site trophoblastic tumor and epitheliod trophoblastic
tumor. [1,2] The
patients’ ages range from 20 to 47 years at diagnosis and the mean age is in
early thirties.[3] It is usually an incidental finding diagnosed
during surgical evaluation for
metro-menorrhagia, hypermenorrhoea, dysmenorrhoea, recurrent abortions,
post-coital bleeding, abnormal cervical smear, or infertility.[2,3]
Placental site nodule mainly is diagnosed microscopically,
but sometimes it is grossly visible in the endometrium or superficial
myometrium as a yellow, tan or a hemorrhagic nodule varying in size from 1 mm
to 1 cm in diameter. Microscopically it has a discrete, well circumscribed ,
lobulated border sometimes showing cells projecting into the surrounding tissue .The intermediate trophoblastic cells
within placental site nodule are embedded in abundant eosinophilic
fibrillar extracellular matrix protein which is the most prominent
feature of placental site nodule. The cells are small to large in size with
hyper chromatic nuclei and often vacuolated cytoplasm.
The placental site nodule is differentiated from other
intermediate trophoblast tumors like placental site trophoblastic tumor,
epitheloid tumor, and certain nontrophoblastic lesions like invasive
keratinizing squamous cell carcinoma of the cervix.
The small size of the lesion, sharp
circumscribed borders, extensive
eosinophilic extracellular matrix, bland and low or absent mitotic activity, lack of necrosis, lower
ki-67 index (<10%) and lack of association with current or recent pregnancy
helps to differentiate a placental site nodule from placental site
trophoblastic tumors ( PSTT) and
epitheliod trophoblastic tumors (ETT). PSTT show trophoblastic infiltration of the
muscle fibers, vasculotropism, extensive deposition of fibrinoid material,
atypical nuclei, frequent mitoses, and
necrosis. ETT show larger lesions with substantial necrosis, are more cellular,
have atypical cells with frequent mitoses. A squamous cell carcinoma, a nontrophoblastic lesion, may also be confused with placental site nodule. Larger
size, greater cytological atypia with mitosis and presence of keratinized cells
are features of squamous carcinoma.
The importance of recognizing this lesion is
because it is benign, does not recur and no specific treatment or
follow-up is required. It needs to be differentiated from other gestational
trophoblastic tumors which are aggressive lesions.[4] However there are some
reports in which PSN transformed into a malignant epithelioid trophoblastic
tumor.[4] However there are some
reports in which PSN transformed into a malignant epithelioid trophoblastic
tumor.[5,6]
References
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clinicopathologic analysis of 20 cases. Am J Surg Pathol 1990;4:1001-9.
2.
Shih IM, Seidman JD, Kurman RJ. Placental site nodule and
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3.
Huettner PC, Gersell DJ. Placental
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4.
Shih IM, Kurman RJ. Ki-67 labeling
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staining technique using Ki-67 and Mel-CAM antibodies. Hum Pathol 1998;29:27-33.
5.
Tsai HW, Lin CP, Chou CY, Li CF, Chow
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of a post-cesarean section placental site nodule into a coexisting epithelioid
trophoblastic tumor and placental site trophoblastic tumor: a case report.Diagnostic
Pathology 2013,8:85. doi:10.1186/1746-1596-8-85
Citation