Reconsideration of the Diagnostic Criteria for an Atypical Placental Site Nodule Comparing Typical Placental Site Nodule of the Uterus: A Report of Two Cases.

Placental site nodules (PSNs) are non-neoplastic remnants of chorionic-type intermediate trophoblastic cells from a previous gestation that form a well-defined single nodule or multiple nodules in the uterine and extrauterine sites. As the cases of PSNs transformed into gestational trophoblastic tumors were described in the literature, "atypical placental site nodules" (APSNs) have been considered as putative transitional lesions between PSNs and gestational trophoblastic tumors. Although histologic criteria and cutoff point of Ki-67 proliferation index for differentiating an APSN from a typical PSN have not been clearly defined, nodules larger than 5 mm with increased cellularity, a corded or nested appearance, marked nuclear atypia, increased mitotic activity, and an increased Ki-67 proliferation index (>5% or >8%) of intermediate trophoblastic cells seem to be accepted as diagnostic criteria for APSNs. However, some of the criteria, including lesion size and histologic features of the trophoblastic cells in the nodule are not only subjective but have features inherent of the intermediate trophoblastic cells of the fetal membrane and a typical PSN. We thought that it is not reasonable to consider them as diagnostic features of APSNs, if not associated with cellular proliferation. We present 2 cases of incidentally identified PSNs that were larger than 10 mm in size with a corded or nested arrangement of trophoblastic cells, which could have been categorized as APSNs according to the currently proposed criteria to discuss whether the currently proposed diagnostic criteria for APSNs are appropriate.

The Rare of the Rarest: Placental Site Trophoblastic Tumor, Epithelioid Trophoblastic Tumor, Atypical Placental Site Nodule.

BACKGROUND: Epithelioid Trophoblastic Tumor (ETT) and Placental Site Trophoblastic Tumor (PSTT) are two of the rarest GTNs that share certain features at diagnosis and management. Atypical Placental Site Nodule (APSN) is a relatively new entity considered as a premalignant lesion. OBJECTIVES AND METHODS: The aim of this review was to summarize the main characteristics of each of these entities, their diagnostic features, and their treatment's standard of care including fertility-sparing treatments. OUTCOME: This study provides a thorough review of ETT, PSTT, and APSN. CONCLUSIONS: The reader will gain an insight view of these rare tumors arising from the intermediate trophoblast.

Differential diagnosis of non-molar gestational trophoblastic neoplasia with ectopic pregnancy by clinical-pathological features.

PURPOSE: This study was presented to investigate the clinical-pathological characteristics of gestational trophoblastic neoplasia (GTN) following non-molar pregnancy and differentiated with ectopic pregnancy (EP). METHODS: The clinical data of 83 patients who were admitted for suspected GTN after non-molar pregnancy at the Women's Hospital School of Medicine Zhejiang University from January 2015 to September 2022 were selected for analysis. RESULTS: In total, 41 cases were confirmed non-molar GTN, including 31 choriocarcinoma, 9 PSTT (placental site trophoblastic tumor), and 1 ETT (epithelioid trophoblastic tumor), while 42 cases were confirmed EP. Compared with ectopic pregnancy, non-molar GTN patients had lower levels of serum progesterone compared with EP (3.81 nmol/L vs 17.70 nmol/L, P = 0.001). Based on the ultrasound, the thickness of the endometrium was thinner in patients with non-molar GTN compared with EP (0.565 cm vs 0.70 cm, P = 0.018). By histopathologic examination, the endothelium of non-molar GTN showed less decidual-like changes compared with EP (64.3% vs 14.6%, P = 0.001). CONCLUSION: A combination of serum progesterone levels, endometrium thickness, and histopathologic features of the endometrium can help to differentiate non-molar GTN and EP. Surgeries including hysteroscopy with curettage and/or laparoscopy are needed.

Molecular Analyses of Chorionic-Type Intermediate Trophoblastic Lesions: Atypical Placental Site Nodules are Closer to Placental Site Nodules Than Epithelioid Trophoblastic Tumors.

Gestational trophoblastic diseases derived from the chorionic-type intermediate trophoblast include benign placental site nodule (PSN) and malignant epithelioid trophoblastic tumor (ETT). Among PSNs, the World Health Organization classification introduced a new entity named atypical placental site nodule (APSN), corresponding to an ETT precursor, for which diagnostic criteria remain unclear, leading to a risk of overdiagnosis and difficulties in patient management. We retrospectively studied 8 PSNs, 7 APSNs, and 8 ETTs to better characterize this new entity and performed immunohistochemical analysis (p63, human placental lactogen, Cyclin E, and Ki67), transcriptional analysis using the NanoString method to quantify the expression of 760 genes involved in the main tumorigenesis pathways, and RNA sequencing to identify fusion transcripts. The immunohistochemical analysis did not reveal any significant difference in Cyclin E expression among the 3 groups (P = .476), whereas the Ki67 index was significantly (P < .001) higher in ETT samples than in APSN and PSN samples. None of the APSN samples harbored the LPCAT1::TERT fusion transcripts, in contrast to 1 of 6 ETT samples, as previously described in 2 of 3 ETT samples. The transcriptomic analysis allowed robust clustering of ETTs distinct from the APSN/PSN group but failed to differentiate APSNs from PSNs. Indeed, only 7 genes were differentially expressed between PSN and APSN samples; CCL19 upregulation and EPCAM downregulation were the most distinguishing features of APSNs. In contrast, 80 genes differentiated ETTs from APSNs, establishing a molecular signature for ETT. Gene set analysis identified significant enrichments in the DNA damage repair, immortality and stemness, and cell cycle signaling pathways when comparing ETTs and APSNs. These results suggested that APSN might not represent a distinct entity but rather a transitional stage between PSN and ETT. RNA sequencing and the transcriptional signature of ETT described herein could serve as triage for APSN from curettage or biopsy material, enabling the identification of cases that need further clinical investigations.

Application of Current Pathologic Criteria for Atypical Placental Site Nodule Suggests That Refined Criteria Are Needed.

Atypical placental site nodules (APSNs) are histologically intermediate between placental site nodules (PSNs) and epithelioid trophoblastic tumors (ETTs). Little data exists to characterize these lesions and the risk of transformation from PSN to ETT. Recent World Health Organization (WHO) criteria for distinction of APSN are vague and not objectively defined. We identified cases signed out as PSN (n=33) and APSN (n=11) and aimed to characterize, statistically compare, and assess the risk of transformation in PSNs using data including size, location, mitotic rate, Ki-67 proliferation index, trophoblastic cells per high-power field, presence of severe cytologic atypia, beta-human chorionic gonadotropin levels, time since last pregnancy, presence of calcification, necrosis, or apoptosis, and follow-up results. All cases were confirmed to be positive for p63, and a Ki-67/AE1/AE3 dual stain was used to evaluate the Ki-67 proliferation index in the trophoblastic cells. In our cohort, slight changes in the interpretation of WHO criteria for PSN and APSN led to marked differences in the proportion of PSNs flagged as "atypical." There was no statistically significant difference in the persistence of APSN versus non-APSN. None of the PSNs transformed to ETT. Current criteria for distinction between PSN and APSN are largely subjective. More objective, clearly defined, and clinically meaningful criteria are needed to distinguish between PSN and APSN, thus aiding in assessing the rare risk of transformation to ETT.

Coexisting Epithelioid Trophoblastic Tumor and Placental Site Trophoblastic Tumor During Asymptomatic Relapse: A Case Report and Literature Review.

Gestational trophoblastic neoplasms are a group of trophoblastic tumors that include choriocarcinoma (CC), epithelioid trophoblastic tumors (ETTs), and placental site trophoblastic tumors (PSTTs). Mixed gestational trophoblastic neoplasms include combinations of CCs with ETTs and/or PSTTs; combinations of ETTs and PSTTs have also been described. This report describes the case of a 49-yr-old female with mixed ETT and PSTT discovered due to menstrual delay and a positive beta-human chorionic gonadotropin in serum 11 yr after normal pregnancy; it is an asymptomatic recurrence of the neoplasm after 2 yr. Moreover, only the ETT recurred without evidence of PSTT by biopsy and without any increase in human chorionic gonadotropin levels, even though human chorionic gonadotropin was positive in the first onset of the disease. We also reviewed published English literature, which revealed that there are only 36 cases of mixed trophoblastic tumors to date, of which pure mixed ETT and PSTT were reported only in four cases including our case. The most common combination is CC admixed with an ETT (52%), followed by CC with PSTT in 30.5%. CC admixed with an ETT and/or PSTT account for 83% of the cases, of which pure mixed ETT and PSTT were reported only in 4 cases (11%). The rarity of this condition entails reporting of all cases to facilitate future research and clinical management.

Gestational trophoblastic neoplasia after human chorionic gonadotropin normalization in a retrospective cohort of 7761 patients in France.

BACKGROUND: The risk of malignant transformation of molar pregnancies after human chorionic gonadotropin levels return to normal is low, roughly 0.4%, but may justify an adaptation of monitoring strategies for certain patients. OBJECTIVE: This study aimed to determine the risk of gestational trophoblastic neoplasia after human chorionic gonadotropin normalization in women with molar pregnancy and identify risk factors for this type of malignant transformation to optimize follow-up protocols after human chorionic gonadotropin normalization. STUDY DESIGN: This was a retrospective observational national cohort study based at the French National Center for Trophoblastic Diseases of 7761 patients, treated between 1999 and 2020 for gestational trophoblastic disease, whose human chorionic gonadotropin levels returned spontaneously to normal. RESULTS: Among 7761 patients whose human chorionic gonadotropin levels returned to normal, 20 (0.26%) developed gestational trophoblastic neoplasia. The risk of malignant transformation varied with the type of mole, from 0% (0 of 2592 cases) for histologically proven partial mole to 0.36% for complete mole (18 of 5045) and 2.1% (2 of 95) for twin molar pregnancy. The median time to diagnosis of malignant transformation after human chorionic gonadotropin normalization was 11.4 months (range, 1-34 months). At diagnosis, 16 of 20 patients (80%) had the International Federation of Gynecology and Obstetrics stage I tumor, and 10 of 20 patients (50%) had a tumor classified as low risk in terms of the International Federation of Gynecology and Obstetrics score. In 9 of 20 patients (45%), the most common first-line treatment was combination chemotherapy. A quarter of these tumors (5 of 20) were histologically proven placental site or epithelioid trophoblastic tumors. In univariate analysis, the factors significantly associated with a higher risk of developing gestational trophoblastic neoplasia after the end of the normal human chorionic gonadotropin monitoring period were age of ≥45 years (odds ratio, 8.3; 95% confidence interval, 2.0-32.7; P=.004) and time to human chorionic gonadotropin normalization of ≥8 weeks (odds ratio, 7.7; 95% confidence interval, 1.1-335; P=.03). The risk was even higher for human chorionic gonadotropin normalization times of ≥17 weeks (odds ratio, 19.5; 95% confidence interval, 3.3-206; P<.001). CONCLUSION: In this group of patients with gestational trophoblastic disease, none of the those with pathologically verified partial mole had malignant transformation, supporting the current recommendation of stopping human chorionic gonadotropin monitoring after 3 successive negative tests. In cases of complete mole or twin molar pregnancy, we proposed to extend the monitoring period with quarterly human chorionic gonadotropin measurements for an additional 30 months in patients with the identified risk factors for late malignant transformation (age, ≥45 years; time to human chorionic gonadotropin normalization, ≥8 weeks).

"It's not lupus". A placental site trophoblastic tumor presenting as a lupus-like paraneoplastic syndrome. A grand round case.

Introduction: Placental site trophoblastic tumor (PSTT) is a rare subtype of gestational trophoblastic disease. Association of PSTT and nephrotic syndrome is exceedingly rare and has been described in 8 cases thus far. In all cases hysterectomy was performed within months after onset of symptoms, leading to immediate remission of nephrotic syndrome, except for one patient who died of complications of PSTT. Case: We describe the history of a woman in which PSTT was discovered years after onset of nephrotic syndrome. Kidney biopsy revealed lupus-like mesangiocapillary nephritis and over time the patient developed additional symptoms mimicking systemic lupus erythematosus (SLE). Discussion: We provide an overview of the literature on this clinical entity and elaborate on its pathophysiology. In addition, we reflect on the phenomenon of anchoring bias, that led physicians to assume the patient had SLE without questioning this diagnosis in the light of the unexplained finding of increased tumor markers.

lnc003875/miR-363/EGR1 regulatory network in the carcinoma -associated fibroblasts controls the angiogenesis of human placental site trophoblastic tumor (PSTT).

The rare gestational trophoblastic neoplasia placental site trophoblastic tumor (PSTT) frequently demonstrates a high degree of vascularization, which may facilitate the tumor metastasis. However, the underlying mechanisms remain largely unknown. In the present study, we found that early growth response 1 (EGR1) was highly expressed in the carcinoma-associated fibroblasts (CAFs) of PSTT tissues. Further data showed that miR-363 down-regulated EGR1 expression whereas long non-coding RNA NONHSAT003875 (lnc003875) up-regulated EGR1 expression in PSTT derived CAFs. lnc003875 exerted no effect on miR-363 expression, but it recovered the decrease of EGR1 caused by miR-363 mimic. The conditioned media from PSTT CAFs treated with miR-363 mimic abrogated the tube formation capacity of human umbilical vein endothelial cells (HUVECs), which can be partially restored by lnc003875 over-expression. Moreover, over-expression of EGR1 promoted the secretion of Angiopoietin-1 (Ang-1) in PSTT derived CAFs and improved the tube formation of HUVECs, which could be effectively abrogated by Ang-1 siRNAs. In vivo vasculogenesis assay demonstrated that lnc003875/EGR1 in PSTT derived CAFs promoted the vasculogenesis of HUVECs in C57BL/6 mice. Collectively, these findings indicated that lnc003875/miR-363/EGR1/Ang-1 in CAFs may be crucial for the angiogenesis of PSTT.

Treatment of gestational trophoblastic disease in the 2020s.

PURPOSE OF REVIEW: This review demonstrates the evidence for new systemic anticancer treatments and how they integrate within conventional management for gestational trophoblastic neoplasia (GTN). We present the evidence on atypical placental site nodules, and how they incorporate within the GTN spectrum, as well as updates regarding GTN staging and follow-up. RECENT FINDINGS: First-line treatment for GTN still lies in conventional chemotherapy, although the introduction of anti-PD1/PD-L1 immune checkpoint inhibitors has shown significant promise in management of relapsed disease, with responses reported in multiple relapsed choriocarcinomas as well as epithelioid trophoblastic tumours and placental site trophoblastic tumours (ETT/PSTT). Following completion of treatment, ETT/PSTT still require life-long surveillance but for other GTN, no recurrences have been detected after 7 years. SUMMARY: Checkpoint inhibitors are likely to play an increasing role in the future management of GTN management. Further refinement of prognostic factors to identify those most at risk of GTN recurrence is warranted so that surveillance can be focussed on those most at risk, whilst minimizing unnecessary intervention for those at lower risk.

Whole transcriptome analysis of gestational trophoblastic neoplasms reveals altered PI3K signaling pathway in epithelioid trophoblastic tumor.

OBJECTIVE: Genomic characteristics of gestational trophoblastic neoplasm (GTN) are mostly unknown. This study reveals the molecular features of malignant GTN, including choriocarcinoma (CC), epithelioid trophoblastic tumor (ETT), and placental site trophoblastic tumor (PSTT), by whole transcriptome sequencing analysis. METHODS: Data obtained from the total RNA sequencing of 2 CC, 4 ETT, and 4 PSTT were evaluated for differential gene expression, pathway alteration, fusion gene, infiltrating immune cell type, PD-L1 and PTEN expression level, and mutation analysis was performed. RESULTS: The transcriptome data were correlated with known biomarkers, including HDS3B1, p63, hCG, and hPL for all tumor types. ETT and PSTT were more closely clustered compared with CC in clustering analysis using gene expression; however, ETT showed various altered signaling pathways, including PI3K-Akt-mTOR, with frequent loss of PTEN protein expression. This finding was both well correlated with PIK3CA c.3140A > G pathogenic mutation, detected in 1 ETT, and further confirmed using the MassARRAY method. PSTT showed an overexpressed gene cluster associated with muscle contraction and G protein-coupled receptor activity. No significant fusion gene was seen in all 10 cases. In tumor-infiltrating immune cell profiles, CD4 memory T cell and macrophage signature were relatively high in ETT and PSTT. PD-L1 mRNA expression level was high in all cases, which was significantly correlated with the PD-L1 level by immunohistochemistry (p = 0.03) with positivity in all 10 cases. CONCLUSIONS: ETT and PSTT were similar at the transcriptome level, with a high level of PD-L1 expression in all tumor types; however, specific pathways, such as PI3K signaling, were altered in ETT.

Placental site trophoblastic disease.

A case study of a 38-year-old woman with a diagnosis of placental site trophoblastic tumor is presented. The patient had a 22-month history of amenorrhea since her last pregnancy, and a dilation and curettage procedure was performed after a 3.1×2.4×2.8 cm endometrial echogenic lesion was visualized on a pelvic ultrasound. When the diagnosis of placental site trophoblastic tumor was made by histopathologic and immunohistochemical analysis, complementary examinations including including pelvic magnetic resonance imaging (MRI) and a chest computed tomography (CT) were done. There was no evidence of disease outside the uterus, and a laparoscopic hysterectomy with bilateral salpingectomy was performed. After a surveillance period of 12 months, no disease recurrence was identified. Best imaging studies, treatment options, and proper surveillance for these type of tumors are discussed alongside the case study.

Atypical Placental Site Nodule Arising in a Postcesarean Section Scar: Case Report and Review of the Literature.

The distinction between benign and malignant trophoblastic lesions often presents a diagnostic challenge, even in entities with defined morphologic and immunohistochemical criteria. Lesions arising from chorionic-type intermediate trophoblast, namely placental site nodule (PSN) and epithelioid trophoblastic tumor (ETT), can be distinguished by existing criteria. However, a putative intermediate lesion termed "atypical placental site nodule" (APSN) has been described in the literature but is not well-classified. We present a case of APSN, along with a brief literature review, and we propose more definitive morphologic and immunohistochemical criteria for this entity, in order to facilitate easier diagnosis and gather more information regarding outcomes.

Extrauterine Placental Site Trophoblastic Tumor Involving the Vagina.

Very few cases of placental site trophoblastic tumor (PSTT) primarily involving extrauterine sites have been reported to date. We report a case of a 29-year-old female who presented with a vaginal nodule 9 months after delivery at an outside hospital which was initially diagnosed as a poorly differentiated squamous cell carcinoma. Subsequently she was referred to our institute, and on the basis of histology, mildly elevated serum ß-HCG level, and immunohistochemistry, PSTT was diagnosed. After the completion of chemotherapy, the vaginal nodule completely regressed and serum ß-hCG returned to baseline. Her follow-up has been unremarkable. This case highlights the importance of the fact that PSTT can be easily misdiagnosed at extrauterine sites in the absence of proper clinical, histologic, and immunohistochemical correlation.

Postoperative chemotherapy on placental site trophoblastic tumor in early stage: analysis of 60 cases.

PURPOSE OF INVESTIGATION: To review the literature of placental site trophoblastic tumor (PSTT) and explore the effect of postoperative chemotherapy in patients with Stage I. MATERIALS AND METHODS: The authors searched literature on Medline, Excerpta Medica Database (EMBASE), and other resources using the keywords "placental site trophoblastic tumor" and "PSTT" from 1981 ito 2014. RESULTS: A total number of 60 patients with Stage I disease were identified, and the presentation, treatment, tumor response, disease status, and follow-up were retrieved and reviewed. According to the authors' knowledge, 725 cases associated with PSTT have been reported in 29 nations/areas since 1981. In this series, the probability of overall survival at ten years in the group of surgery alone and postoperative chemotherapy were 96.7% and 79.1% (p = 0.199), and recurrence-free survival rates were 91.8% and 63.3%, respectively. CONCLUSION: The benefit from postoperative chemotherapy is still equivocal. There is a need for scrupulousness before adding postoperative chemotherapy.

Placental site trophoblastic tumor in early stage: a case report.

Here, the authors present a case of a placental site trophoblastic tumor (PSTT) in a 28-year-old gravida 1 para 1 living 1 woman three months after vaginal delivery of a female infant at diagnosis in 2014. The patient was FIGO Stage I and finally underwent a total laparoscopic hysterectomy with ovarian conservation. Subsequently, the patient received two cycles of EMA/CO chemotherapy. Patient is on regular follow-up (clinical exam, ß-hCG tests, pelvic and abdominal sonography) and has shown no signs of local or systemic recurrence for 24 months.

Placental site trophoblastic tumor: A review of 108 cases and their implications for prognosis and treatment.

OBJECTIVE: To identify important prognostic factors and optimized treatment strategies through the analysis of the clinical and pathological characteristics of placental site trophoblastic tumor. METHODS: 108 patients with PSTT registered in two GTD centers or in six tertiary hospitals in China were analyzed retrospectively between the years 1998 and 2013. The computerized database of clinical and pathological reports was reviewed on this patient group. The data were subsequently analyzed retrospectively using SPSS software. RESULTS: Among 3581 patients with GTNs treated in GTD centers or in the tertiary hospitals between 1998 and 2013, 108 cases were histologically confirmed PSTT (3%). Only seven deaths and eleven relapse cases were observed. All seven of the deaths were disease related, due to chemotherapy-resistant or relapsed. 23 patients who received fertility preservation treatment did not experience poor outcome or high risk of relapse. In 71 patients with International Federation of Gynecology and Obstetrics (FIGO) stage I disease, the use of adjuvant chemotherapy following surgery (n=49) or not (n=22) made no significant difference in relapse rate (P=0.303) or survival (P=0.782). Univariate analysis revealed the interval between antecedent pregnancy and onset of PSTT, stage, prognosis score, and necrosis as significant predictors of poor survival but only stage remained significant on multivariate analysis. CONCLUSIONS: Patients with FIGO stage IV disease demonstrate the most critical risk indicator of PSTT in the current study. Preservation of fertility is considered in highly-selected patients with localized tumor; and surgery without chemotherapy is recommended as first line treatment for patients with stage I who are at low-risk.

Molecular genotyping of placental site and epithelioid trophoblastic tumours; female predominance.

OBJECTIVE: To investigate a large series of placental site trophoblastic tumours (PSTT) and epithelioid trophoblastic tumours (ETT) and determine the relationship between their development and the type and sex of both the immediately antecedent and causative pregnancies. METHODS: The antecedent pregnancy was determined from patient records in 92 cases with a confirmed diagnosis of PSTT, ETT or mixed PSTT/ETT. In a subset of 57 cases, type and sex of the causative pregnancy was established by molecular genotyping of tumour tissue microdissected from formalin-fixed, paraffin-embedded blocks. RESULTS: The antecedent pregnancy was a normal live birth in 59 (64%) cases, a hydatidiform mole in 19 (21%) and other pregnancy loss in 14 (15%). Where the sex was recorded, 36 (78%) of 46 antecedent normal pregnancies were female, a significantly greater proportion than expected (p<0.0001). Genotyping of 57 cases found 15 (26%) to derive from hydatidiform moles while 42 (74%) arose in non-molar pregnancies. Where the causative pregnancy was non-molar, 38 (91%) tumours arose in female conceptions, significantly greater than expected (p<0.0001). Analysis of short tandem repeats on the X chromosome in three tumours with an XY chromosomal constitution confirmed that the X chromosome was maternal in origin. CONCLUSIONS: PSTT and ETT predominantly arise in female pregnancies but can develop in male pregnancies. A male derived X chromosome is not required for the development of these tumours. While these tumours are predominantly female it is not because most originate in complete hydatidiform moles.

Placental Site Trophoblastic Tumors: Analysis of the Clinicopathologic Characteristics of 20 Cases in Korea.

OBJECTIVES: The aim of this study was to evaluate the clinicopathologic features of placental site trophoblastic tumors (PSTTs) in Korea. METHODS/MATERIALS: Twenty patients given a diagnosis of PSTT in Korea (1990-2013) were evaluated retrospectively, including 14 patients identified through a literature review and 6 patients identified through a medical chart review of a single institution. The analysis included patient age, antecedent pregnancies, time since antecedent pregnancy, presenting symptoms, serum ß-human chorionic gonadotropin level, International Federation of Gynecology and Obstetrics stage, treatment, outcome, and follow-up. RESULTS: The mean age of the 20 patients was 32 years (range, 25-53 years). The antecedent pregnancies included 8 term pregnancies, 8 abortions, and 2 molar pregnancies. The time since the antecedent pregnancy was less than 1 year in 16 patients (80%). Nineteen patients (95%) presented with abnormal vaginal spotting or amenorrhea. Serum ß-human chorionic gonadotropin levels ranged from normal to 13,480 mIU/mL, although most patients (80%) had a level less than 1000 mIU/mL. Seventeen patients (85%) presented with stage I disease. Ten patients (50%) underwent hysterectomy, and 14 patients (70%) were treated with chemotherapy with or without hysterectomy. In 11 evaluated patients, the median mitotic count index was 3.4 (0.4-10) per 10 high-power fields. The median follow-up time was 17 months (range, 1-68 months). There was no recurrence or death from disease. CONCLUSIONS: Korean patients with PSTT often have early-stage disease, which has a favorable prognosis even with fertility-preserving therapy. However, international studies are necessary to determine the optimal treatment and prognostic factors.