Intrauterine placental site nodule or plaque: a case description

Introduction

Placental site nodule or plaque (PSNP) is a rare type of gestational trophoblastic disease, classified as a non-neoplastic trophoblastic lesion associated with pregnancy (1). This disease predominantly affects individuals aged 27 to 45 years (2). The most common clinical manifestations of the disease are menorrhagia and irregular uterine bleeding (2). The lesions are primarily located in the uterine cavity, and extrauterine involvement is relatively uncommon. In cases of extrauterine lesions, the fallopian tube is the most frequently affected site, followed by the ovary (3).

PSNP is commonly detected in specimens obtained post-evacuation, hysterectomy, or curettage, frequently in the context of secondary infertility. PSNP is formed by the proliferation of chorionic intermediate trophoblast cells. These lesions typically present as well-defined, round or oval nodules, or plaque-like formations (4).

The expression of cytokeratins, CD10, and α-inhibin is high in PSNP, while the expression of chorion-related factors such as human chorionic gonadotropin (hCG) and human placental lactogen is low, as is the Ki-67 proliferation index (5). The literature on this disease has largely focused on the field of pathology, with few detailed reports on imaging studies.

Although histopathological examination remains the gold standard for the diagnosis of PSNP, imaging techniques can provide profound auxiliary diagnostic information preoperatively. Conventional gynecological imaging modalities, such as hysterosalpingography, magnetic resonance imaging (MRI), and ultrasonography, can clearly delineate the space-occupying characteristics of PSNP (6). Among these, MRI and ultrasonography can not only be used to assess the vascularity of the lesion but can also be used to precisely evaluate its anatomical relationship with adjacent tissues. However, systematic studies on the imaging manifestations of PSNP are limited, particularly those providing high-quality, detailed multimodal imaging data.

This article presents a case of PSNP that was evaluated using standardized ultrasonography and MRI. Our findings may optimize the clinical imaging assessment of such lesions.

Case presentation

A 24-year-old female presented to the Department of Obstetrics and Gynecology with a 5-year history of recurrent fever, accompanied by irregular vaginal bleeding for more than 2 weeks. Her medical history revealed that the patient had a total of five pregnancies, including two spontaneous abortions and three term deliveries. The most recent pregnancy was terminated by a drug-induced medical abortion 12 months prior to the current visit. The patient’s last menstrual period occurred 2 months before presentation.

Laboratory tests at admission revealed an elevated hCG level of 166.2 mIU/mL (reference range, 0–10 mIU/mL). Contrast-enhanced pelvic MRI (Figure 1) showed a large, vascular mass in the uterus extending to the anterior myometrium, near the uterine cavity with a rich blood supply, suggestive of a gestational trophoblastic neoplasm. Transvaginal ultrasound (Figure 2) revealed an enlarged uterus containing a mixed echogenic mass with increased vascularity in the uterine cavity, suggestive of a potential trophoblastic neoplasm.

Figure 1 Pelvic MRI images of the patient. (A) The intrauterine mass exhibited high signal intensity on diffusion-weighted imaging. (B) The mass showed low signal intensity on apparent diffusion coefficient mapping. (C) The uterine body was significantly enlarged, and the mass showed an intermediate/slightly hyperintense signal on T1-weighted imaging. (D) The mass displayed high signal intensity on T2-weighted imaging. (E,F) On contrast-enhanced MRI, the mass extended from the anterior wall and base of the uterine body into the deep myometrium, exhibiting marked enhancement. MRI, magnetic resonance imaging.

Figure 2 Ultrasound image of the patient. (A) Enlarged uterus with an indistinct-margin mixed echogenic mass in the myometrium. (B) Increased vascularity in the mass on color Doppler.

Based on the laboratory and imaging examinations, either an incomplete abortion or an invasive trophoblastic tumor was suspected. Given the patient’s young age and the significant trauma associated with total hysterectomy, diagnostic curettage was prioritized for definitive diagnosis. Uterine evacuation was conducted 3 days later, during which 80 grams of retained products of conception were removed. The postoperative histopathological examination revealed PSNP.

The patient recovered well without complications. Follow-up Doppler ultrasound demonstrated normal uterine morphology and size, with no significant abnormal echoes and blood flow signals detected in the uterine cavity. Additionally, no remarkable abnormalities were observed in the bilateral adnexal regions. Her hCG level remained within the normal reference range.

All the procedures in this case were performed in accordance with the ethical standards of the institutional and/or national research committee(s), and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and the accompanying images. A copy of the written consent form is available for review by the editorial office of this journal.

Discussion

PSNP typically presents with irregular vaginal bleeding as its primary clinical manifestation, which is consistent with this patient’s symptoms. Reports indicate that PSNP most commonly occurs within 48 months of the last pregnancy (7,8). This patient, a woman of reproductive age with a history of abortion 12 months prior to presentation, fits this epidemiological profile. Both the ultrasound and contrast-enhanced MRI imaging findings showed a hypervascular mass in the uterine cavity with ill-defined borders and indistinct demarcation from the myometrium. Such imaging features are easily confused with choriocarcinoma. However, the key distinguishing factor was the patient’s hCG level, which was only slightly elevated. This finding differs markedly from the characteristic hundreds-to-thousands-fold increase typically observed in choriocarcinoma (9). This discrepancy stems from the pathological nature of PSNP, which is composed of intermediate trophoblast cells that have a far lower hCG capacity than the cytotrophoblast cells of choriocarcinomas or invasive moles.

Given the patient’s history of medical abortion and slightly elevated hCG level, incomplete abortion could not be entirely excluded. However, incomplete abortion typically presents on imaging as a lesion with heterogeneous signal/echogenicity and punctate or nodular vascularity—features inconsistent with those observed in this case. Conversely, PSNP typically exhibits relatively uniform signal intensity/echogenicity, an abundant blood supply, and a slightly elevated hCG level, which aligned with the laboratory findings and radiological characteristics observed in this case. Notably, PSNP is relatively rare in clinical practice and lacks specific radiological characteristics. Further, no definitive diagnostic threshold for hCG has been established to date.

Histopathologically, nodules and plaques at the placental site degenerate after delivery, eventually forming single or multiple small, distinct nodules or plaques. As a result, the size of PSNP is influenced by the size of the unseparated fetal membranes (10). According to the World Health Organization’s classification of female reproductive tumors (5th edition) (11), PSNP typically presents as a lesion with a diameter ranging from 5 to 10 mm, a nucleus that is not significantly enlarged, and uniform chromatin. PSNP is characterized by low trophoblastic proliferative activity, with a Ki-67 labeling index of less than 8% (1). PSNP is essentially a benign lesion that can typically be completely resolved following uterine curettage. However, it also carries a potential risk of progression into a placental site trophoblastic tumor, characterized by pathological features such as nodule enlargement, increased cellular density, cord-like/nested growth patterns, and cellular proliferation (12). Therefore, patients should undergo follow-up monitoring with ultrasound and hCG testing after curettage.

PSNP shares similarities with other trophoblastic tumors—both present as hemorrhagic masses with indistinct margins. In reproductive-aged women with a history of incomplete abortion but without significantly elevated serum hCG levels, PSNP should be considered.

Acknowledgments

None.

Footnote

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1303/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this case were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Kaur B. Pathology of gestational trophoblastic disease (GTD). Best Pract Res Clin Obstet Gynaecol 2021;74:3-28. [Crossref] [PubMed]
2. Young RH, Kurman RJ, Scully RE. Placental site nodules and plaques. A clinicopathologic analysis of 20 cases. Am J Surg Pathol 1990;14:1001-9. [Crossref] [PubMed]
3. Geetha SD, Roychoudhury S, Sham S, Truskinovsky AM. A Rare Placental Site Nodule Involving the Ovary. Int J Surg Pathol 2025;33:745-8. [Crossref] [PubMed]
4. Shih IM, Kurman RJ. The pathology of intermediate trophoblastic tumors and tumor-like lesions. Int J Gynecol Pathol 2001;20:31-47. [Crossref] [PubMed]
5. Huang F, Zheng W, Liang Q, Yin T. Diagnosis and treatment of placental site trophoblastic tumor. Int J Clin Exp Pathol 2013;6:1448-51.
6. Sakhel K, Khalil A, Kaspar H, Azar G, Mansour A, Nassar A. Placental site trophoblastic tumor in a patient with secondary infertility and radiological findings consistent with a leiomyoma: a case report. Int J Gynecol Cancer 2004;14:694-6. [Crossref] [PubMed]
7. Marquina G, Szewczyk G, Goffin F. The Rare of the Rarest: Placental Site Trophoblastic Tumor, Epithelioid Trophoblastic Tumor, Atypical Placental Site Nodule. Gynecol Obstet Invest 2024;89:239-46. [Crossref] [PubMed]
8. Froeling FEM, Ramaswami R, Papanastasopoulos P, Kaur B, Sebire NJ, Short D, Fisher RA, Sarwar N, Wells M, Singh K, Ellis L, Horsman JM, Winter MC, Tidy J, Hancock BW, Seckl MJ. Intensified therapies improve survival and identification of novel prognostic factors for placental-site and epithelioid trophoblastic tumours. Br J Cancer 2019;120:587-94. [Crossref] [PubMed]
9. Feng X, Wei Z, Zhang S, Du Y, Zhao H. A Review on the Pathogenesis and Clinical Management of Placental Site Trophoblastic Tumors. Front Oncol 2019;9:937. [Crossref] [PubMed]
10. Jo U, Kim GH, Kim KR. Reconsideration of the Diagnostic Criteria for an Atypical Placental Site Nodule Comparing Typical Placental Site Nodule of the Uterus: A Report of Two Cases. Int J Gynecol Pathol 2024;43:61-6. [Crossref] [PubMed]
11. McCluggage WG, Singh N, Gilks CB. Key changes to the World Health Organization (WHO) classification of female genital tumours introduced in the 5th edition (2020). Histopathology 2022;80:762-78.
12. Gadducci A, Carinelli S, Guerrieri ME, Aletti GD. Placental site trophoblastic tumor and epithelioid trophoblastic tumor: Clinical and pathological features, prognostic variables and treatment strategy. Gynecol Oncol 2019;153:684-93. [Crossref] [PubMed]