Placental Site Nodule

Author Information

Kimaya Mali*, Fernandes G**, Vibha More*, M. N. Satia***
(* Assistant Professor, *** Professor, Department of Obstetrics & Gynecology, ** Associate Professor, Department of Pathology, Seth GS Medical College & KEM Hospital, Parel, Mumbai, India.)


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.


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)


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]


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2.      Shih IM, Seidman JD, Kurman RJ. Placental site nodule and characterization of distinctive types of intermediate trophoblast. Hum Pathol 1999;30:687-94.
3.      Huettner PC, Gersell DJ. Placental site nodule: a clinicopathologic study of 38 cases. Int J Gynecol Pathol 1994;13(3):191-8.
4.      Shih IM, Kurman RJ. Ki-67 labeling index in the differential diagnosis of exaggerated placental site, placental site trophoblastic tumor, andchoriocarcinoma: a double immunohistochemical 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 NH, Shih IM, Ho CL. Placental site nodule transformed into a malignant epithelioid trophoblastic tumour with pelvic lymph node and lung metastasis. Histopathology 2008;53:601–604. doi: 10.1111/j.1365-2559.2008.03145.x
6.      Bo-Jung C, Chien-Jui C, Wei-Yu C.Transformation 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


Mali K, Fernandes G, More V, Satia MN. Placental Site Nodule. JPGO 2014. Volume 1 Number 10. Available from: