The Microcystic, Elongated, and Fragmented (MELF) Pattern of Invasion: A Single Institution Report of 464 Consecutive FIGO Grade 1 Endometrial Endometrioid Adenocarcinomas

Enhancing prognostic insights: myometrial invasion patterns in endometrial carcinoma, with emphasis on MELF pattern-a comprehensive review and meta-analysis

PURPOSE

The microcystic, elongated, and fragmented (MELF) pattern, characterized by myxoid and inflamed stroma, is readily identifiable as a form of myometrial infiltration. This meta-analysis endeavors to assess the prognostic significance of MELF infiltration patterns in patients diagnosed with endometrial cancer.

METHODS

A comprehensive literature search, spanning until 11 October 2023, across PubMed, Embase, Cochrane, and Web of Science databases, identified 23 relevant studies involving 5199 patients. Data analysis was performed using Stata 16.0.

RESULTS

Analysis indicates that MELF infiltration predicts a higher risk of lymph node metastasis in endometrial cancer patients [hazard ratios (HR) = 5.05; 95% confidence interval (CI), 3.62-7.05; P < 0.05]. Notably, this association remains consistent across various patient demographics, analytical approaches, study designs, and treatment modalities. However, MELF infiltration does not significantly correlate with recurrence (HR = 1.05; 95% CI, 0.73-1.52; P > 0.05), overall survival (HR = 1.24; 95% CI, 0.91-1.68; P > 0.05), or disease-free survival (HR = 1.40; 95% CI, 0.85-2.28; P > 0.05).

CONCLUSION

While MELF infiltration heightens the risk of lymph node metastasis in endometrial cancer, its impact on recurrence, overall survival, and disease-free survival remains statistically insignificant.

Molecular Classification of Endometrial Endometrioid Carcinoma With Microcystic Elongated and Fragmented Pattern

The studies on the molecular classification of endometrioid carcinoma (EC) with microcystic, elongated, and fragmented (MELF) pattern invasion are limited. In this study, 77 cases of ECs with MELF patterns in Chinese women were collected. The molecular classification of the fifth edition of the World Health Organization was used to classify the molecular subtypes using immunohistochemistry staining (mismatch repair [MMR]-immunohistochemistry: MSH2, MSH6, MLH1, and PMS2; p53) and Sanger sequencing targeted POLE . The results showed that the prevalence of the 4 molecular subtypes in EC with MELF pattern was 6.5% (5/77) for POLE mutation, 20.8% (16/77) for MMR deficient, 11.7% (9/77) for p53-mutant, and 61.0% (47/77) for no specific molecular profile. The clinicopathological characteristics of each subtype were compared. The p53-mutant and no specific molecular profile subgroups were associated with higher International Federation of Gynecology and Obstetrics stage and International Federation of Gynecology and Obstetrics grade, deeper myometrial invasion, lymphovascular space invasion, lymph node metastasis, and absence of tumor-infiltrating lymphocytes, whereas the POLE mutation and MMR deficient subgroups were associated with lower aggressive features and prominent tumor-infiltrating lymphocytes. Progression-free survival showed that the p53-mutant and no specific molecular profile subgroups had a poorer prognosis than the POLE mutation and MMR deficient subgroups. However, lymph node metastasis was an independent factor associated with a higher risk of disease recurrence in multivariate analysis. In conclusion, ECs with MELF patterns can be divided into 4 molecular subtypes with discrepancies in aggressive clinicopathological characteristics and tumor-infiltrating lymphocytes. Molecular classification has clinical significance in a morpho-molecular approach for ECs with MELF patterns.

Endocervical Adenocarcinoma Showing Microcystic, Elongated, and Fragmented (MELF) Pattern of Stromal Invasion: A Single-Institutional Analysis of 10 Cases with Comprehensive Clinicopathological Analyses and Ki-67 Immunostaining

Microcystic, elongated, and fragmented (MELF) pattern of invasion has seldom been documented in endocervical adenocarcinoma (EAC). The aim of this study was to analyze the clinicopathological characteristics of EAC showing MELF pattern. We collected the clinicopathological information of 10 cases of EAC with the MELF pattern and conducted polymer-based immunostaining for Ki-67 (dilution 1:200, clone MIB-1) on these cases. Ki-67 expression was assessed using the average estimation within the hotspot method. All tumors were human papillomavirus-associated EAC with Silva pattern C. All except one tumor exceeded 3 cm in size. Five tumors involved the entire thickness of the cervical stroma, and four tumors extended into the parametrium. Lymphovascular space invasion was identified in six cases. Two patients developed metastatic recurrences in the para-aortic lymph nodes and lungs, respectively. The MELF area showed significantly lower Ki-67 labelling index than that of a conventional tumor area. We confirmed our previous observation that the MELF area displayed lower proliferative activity than the conventional tumor area of EAC. We also demonstrated that patients with EAC showing MELF pattern had several adverse clinicopathological characteristics reflecting aggressive behavior. On the other hand, since the frequencies of post-operative recurrence and disease-related mortality that occurred during the follow-up period were relatively low, further investigations are warranted to clarify the prognostic value of MELF pattern in EAC patients.

Can the microcystic, elongated and fragmented pattern of invasion influence the evaluation of the depth of myometrial invasion in low-grade endometrioid endometrial cancer using imaging techniques?

Objectives

The microcystic, elongated and fragmented pattern of invasion can be associated with an underestimation of the depth of myometrial invasion by imaging techniques. We aimed to evaluate the influence of microcystic, elongated and fragmented pattern of invasion in the diagnostic performance of transvaginal ultrasound scan and magnetic resonance imaging for the prediction of the depth of myometrial invasion in low-grade endometrioid endometrial carcinomas.

Methods

Prospective and consecutive study including all low-grade (G1-G2) endometrioid endometrial carcinomas diagnosed between October 2013 and July 2018 in a tertiary hospital. Preoperative staging was performed with transvaginal ultrasound scan and/or magnetic resonance imaging followed by surgical staging. Final histology was considered as the reference standard. Sensitivity, specificity and diagnostic accuracy for the prediction of depth of myometrial invasion was calculated for both imaging techniques. The STARD 2015 guidelines were used.

Results

A total of 136 patients were consecutively included. Transvaginal ultrasound scan was performed in 132 patients and magnetic resonance imaging in 119 patients. The diagnostic accuracy of transvaginal ultrasound scan for the prediction of depth of myometrial invasion in the microcystic, elongated and fragmented negative group (82% (95% confidence interval = 73-88)) was higher compared to the microcystic, elongated and fragmented positive group (61% (95% confidence interval = 36-83)). The diagnostic accuracy of magnetic resonance imaging was also higher in the microcystic, elongated and fragmented negative group (80% (95% confidence interval = 71-87)) compared to the microcystic, elongated and fragmented positive (47% (95% confidence interval = 21-73)).

Conclusions

In low-grade endometrioid endometrial carcinomas with a positive microcystic, elongated and fragmented pattern of invasion, the evaluation of the depth of myometrial invasion using transvaginal ultrasound scan and magnetic resonance imaging may be underestimated.

Single-cell profiling of low-stage endometrial cancers identifies low epithelial vimentin expression as a marker of recurrent disease

BACKGROUND

Identification of aggressive low-stage endometrial cancers is challenging. So far, studies have failed to pinpoint robust features or biomarkers associated with risk of recurrence for these patients.

METHODS

Imaging mass cytometry was used to examine single-cell expression of 23 proteins in 36 primary FIGO IB endometrial cancers, of which 17 recurred. Single-cell information was extracted for each tumor and unsupervised clustering was used to identify cellular phenotypes. Distinct phenotypes and cellular neighborhoods were compared in relation to recurrence. Cellular differences were validated in a separate gene expression dataset and the TCGA EC dataset. Vimentin protein expression was evaluated by IHC in pre-operative samples from 518 patients to validate its robustness as a prognostic marker.

FINDINGS

The abundance of epithelial, immune or stromal cell types did not associate with recurrence. Clustering of patients based on tumor single cell marker expression revealed distinct patient clusters associated with outcome. A cell population neighboring CD8+ T cells, defined by vimentin, ER, and PR expressing epithelial cells, was more prevalent in non-recurrent tumors. Importantly, lower epithelial vimentin expression and lower gene expression of VIM associated with worse recurrence-free survival. Loss and low expression of vimentin was validated by IHC as a robust marker for recurrence in FIGO I stage disease and predicted poor prognosis also when including all patients and in endometrioid patients only.

INTERPRETATION

This study reveals distinct characteristics in low-stage tumors and points to vimentin as a clinically relevant marker that may aid in identifying a here to unidentified subgroup of high-risk patients.

FUNDING

A full list of funding that contributed to this study can be found in the Acknowledgements section.

Robotic omentectomy in gynecologic oncology: surgical anatomy, indications, and a technical approach

An omentectomy is a standard component care of gynecological cancers, particularly for surgical staging and treatment for malignant ovarian neoplasms, borderline tumors, fallopian tube cancers, primary peritoneal cancers as well as certain histological subtypes of endometrial cancer. Traditionally, an omentectomy is performed by an open laparotomy approach, however, use of a robotic approach has gained popularity and has been proven to be both safe and effective. In spite of the advantages of robotic surgery compared to laparotomy, the inherent technical challenges of a robotic omentectomy may limit its uptake. In this article, we review (1) the physiology and surgical anatomy of the omentum, (2) the role of the omentum in immune regulation and oncogenesis, (3) indications for an omentectomy in the setting of gynecological malignancy, and (4) describe a step-by-step 3-arm technique for performing both a infracolic and gastrocolic omentectomy procedure using a robotic approach.

Development of a novel predictive model for lymph node metastasis in patients with endometrial endometrioid carcinoma

BACKGROUND

Globally, the burden of endometrial endometrioid carcinoma (EEC) increases annually. However, the histological grade of EEC remains unelucidated. We developed a novel model for predicting lymph node metastasis (LNM) in patients with endometrioid carcinoma (EC), which has not been well established.

METHODS

A total of 344 patients with EEC were classified into training (n = 226) and validation (n = 118) cohorts. To develop a nomogram to predict LNM, independent predictors were defined using univariate and multivariate regression analyses. The calibration curve, area under the decision curve analysis (DCA), and receiver operating characteristic curve were used to evaluate the performance of the nomogram.

RESULTS

Independent predictors of LNM in EC were identified in the univariate analysis, including mitosis; microcystic, elongated, and fragmented patterns; lymphovascular invasion (LVI); necrosis; and high-grade pattern. Mitosis, LVI, and high-grade pattern remained independent predictors of LNM in multivariate analysis. An LNM nomogram that was constructed by incorporating the five predictors showed reliable discrimination and calibration. DCA showed that the LNM nomogram scoring system had significant clinical application value. In addition, a high nomogram score (score > 150) was a significant prognosticator for survival in both LNM-positive and LNM-negative ECs.

CONCLUSIONS

Our novel predictive model for LNM in patients with EC has the potential to assist surgeons in making optimal treatment decisions.

Data Set for the Reporting of Endometrial Cancer: Recommendations From the International Collaboration on Cancer Reporting (ICCR)

Endometrial cancer is one of the most common cancers among women. The International Collaboration on Cancer Reporting (ICCR) developed a standardized endometrial cancer data set in 2011, which provided detailed recommendations for the reporting of resection specimens of these neoplasms. A new data set has been developed, which incorporates the updated 2020 World Health Organization Classification of Female Genital Tumors, the Cancer Genome Atlas (TCGA) molecular classification of endometrial cancers, and other major advances in endometrial cancer reporting, all of which necessitated a major revision of the data set. This updated data set has been produced by a panel of expert pathologists and an expert clinician and has been subject to international open consultation. The data set includes core elements which are unanimously agreed upon as essential for cancer diagnosis, clinical management, staging, or prognosis and noncore elements which are clinically important, but not essential. Explanatory notes are provided for each element. Adoption of this updated data set will result in improvements in endometrial cancer patient care.

Microcystic, elongated and fragmented (MELF) pattern in endometrial carcinoma: clinicopathologic analysis and prognostic implications

To assess the clinical value of microcystic, elongated, and fragmented (MELF) pattern in Chinese patients with endometrial endometrioid carcinoma. A total of 189 patients with endometrial endometrioid carcinoma were retrospectively analyzed in Peking University Third Hospital from January 2017 to December 2019. We analyzed the association of MELF pattern with the histopathologic data and prognosis of the patients, while immunohistochemistry was performed. The frequency of MELF pattern was 17.99% (34/189). MELF pattern was associated significantly with tumor size, myometrial invasion, histological grade, International Federation of Gynecology and Obstetrics stages, lymphovascular space invasion, and lymph node metastasis. According to multivariate logistic regression analysis, lymphovascular space invasion [95% confidence interval 1.021-48.485, P = .048] was a significant predictor of lymph node involvement. However, MELF pattern was not a significant predictor (95% confidence interval 0.054-2.279, P = .400). Loss of expression for mismatch repair proteins was observed in 10 MELF + cases (29.41%) and 54 MELF- cases (34.84%), respectively. All patients were followed up for 36.8 ± 8.9 months (18-54 months). Only 1 patient with MELF pattern was diagnosed with vaginal recurrence 28 months after the surgery. MELF pattern was associated with adverse histologic findings in endometrial endometrioid carcinomas. However, MELF pattern was statistically not a valuable predictor of lymph node metastasis and it needs more studies to show whether MELF pattern has an impact on the prognosis of patients with endometrial endometrioid carcinoma. MELF pattern may be important for identifying those patients who need comprehensive staging surgery.

Microcystic elongated and fragmented (MELF) pattern of invasion: Molecular features and prognostic significance in the PORTEC-1 and -2 trials

OBJECTIVE

Microcystic, elongated fragmented (MELF) pattern of myometrial invasion is a distinct histologic feature occasionally seen in low-grade endometrial carcinomas (EC). The prognostic relevance of MELF invasion was uncertain due to conflicting data, and it had not yet appropriately been studied in the context of the molecular EC classification. We aimed to determine the relation of MELF invasion with clinicopathological and molecular characteristics, and define its prognostic relevance in early-stage low/intermediate risk EC.

METHODS

Single whole tumor slides of 979 (85.8%) out of 1141 (high)intermediate-risk EC of women who participated in the PORTEC-1/-2 trials were available for review. Clinicopathological and molecular features were compared between MELF invasion positive and negative cases. Time-to-event analyses were done by Kaplan-Meier method, log-rank tests and Cox' proportional hazards models.

RESULTS

MELF invasion was found in 128 (13.1%) cases, and associated with grade 1-2 histology, deep myometrial invasion and substantial lymph-vascular space invasion (LVSI). 85.6% of MELF invasion positive tumors were no-specific-molecular-profile (NSMP) EC. NSMP EC with MELF invasion were CTNNB1 wild type in 92.2% and KRAS mutated in 24.4% of cases. Risk of recurrence was lower for MELF invasion positive as compared to MELF invasion negative cases (4.9% vs. 12.7%, p = 0.026). However, MELF invasion had no independent impact on risk of recurrence (HR 0.65, p = 0.30) after correction for clinicopathological and molecular factors.

CONCLUSIONS

MELF invasion has no independent impact on risk of recurrence in early-stage EC, and is frequently observed in low-grade NSMP tumors. Routine assessment of MELF invasion has no clinical implications and is not recommended.

Clinicopathologic association and prognostic impact of microcystic, elongated and fragmented pattern invasion, combined with tumor budding in endometrioid endometrial cancer

AIM

As a special invasive pattern seen in low-grade endometrial carcinoma, microcystic, elongated and fragmented (MELF) pattern is related to lymph node metastasis. Tumor budding (TB) is another histological marker in many cancers associated with tumor aggressiveness. Herein, we evaluated the impact of MELF pattern combined with TB about clinicopathological features and prognosis in endometrioid endometrial cancer (EEC). To verify the relationship between the two morphological markers and microsatellite status in EEC, the primary mismatch repair (MMR) proteins were detected by immunohistochemistry.

METHODS

One hundred and seventy-two cases of ECC diagnosed between 2011 and 2016 were reviewed with a median follow up of 47.5 months. MELF pattern and TB were examined on all H&E-stained slides. Primary MMR proteins (MLH1, MSH2, MSH6, and PMS2) were also detected.

RESULTS

Based on MELF pattern and TB, 172 patients were divided into the following four groups: MELF(-)/TB(+) (n = 41), MELF(+)/TB(-) (n = 15), MELF(+)/TB(+) (n = 20), and MELF(-)/TB(-) (n = 96). Adverse pathological features were observed in the MELF(+)/TB(+) group: 70% presented deep muscular infiltration, 65% were lymphovascular space invasion, and 25% suffered lymph node metastasis. The proportion of MMR deficient in MELF(+)/TB(-) group was the highest (66.7%). The progression-free survival (PFS) and overall survival (OS) among the four groups were significantly different. MELF(+)/TB(+) group showed the worst PFS and OS. As univariate and multivariate survival analyses revealed, the combination of MELF pattern and TB was confirmed as an independent predictor of poor prognosis.

CONCLUSIONS

Our research demonstrates that MELF pattern combined with TB, as an independent predictor of adverse outcome, is associated with adverse pathological features, which facilitates better understanding of EEC tumor behavior and more precise prognosis without additional medical expense.

Understanding the role of indoleamine-2,3-dioxygenase and stromal differentiation in rare subtype endometrial cancer

Endometrial cancer (EC) is a disease with good and poor prognostic subtypes. Dedifferentiated endometrial carcinoma (DEC), undifferentiated endometrial carcinoma (UEC), and clear cell endometrial carcinoma (CEC) are rare high-grade tumors, associated with a poor prognosis and high pathologic stage. Many studies have been performed on the programmed death-ligand 1 (PD-L1) axis mainly focus on endometrioid adenocarcinomas and little research has been done on rare subtypes. The present body of work aims to evaluate the role of indoleamine-2,3-dioxygenase (IDO-1) and stromal differentiation (SD), their correlation with clinicopathologic features and overall survival. Here we found that positive IDO-1 expression in immune cells correlated with worse disease-free survival (p = 0.02), recurrence (p = 0.03), high pathologic tumor stage (p = 0.024), lymph node metastasis (p = 0.028), and myometrial invasion (p = 0.03). Our findings suggest IDO-1 to be relevant in both MMR intact and deficient tumors; however, >20% immune cell staining was restricted to MMR deficient cancers. For the stroma, immature, myxoid differentiation was found to correlate with worse disease-free survival (p = 0.04). We also found the correlation between IDO-1 expression and immature stroma. Looking forward, IDO-1 could be promising for immunotherapy and SD could be the answer to clinical heterogeneity.

Patterns of Myometrial Invasion in Endometrial Adenocarcinoma with Emphasizing on Microcystic, Elongated and Fragmented (MELF) Glands Pattern: A Narrative Review of the Literature

Endometrioid endometrial adenocarcinoma (EEC) is the most common malignancy of the female genital tract. According to the 2009 FIGO staging system, the depth of myometrial invasion (MI), and tumor spread to adjacent organs or tissues are the staging criteria for endometrial carcinoma (EC). Therefore, assessment of the depth of MI is of great importance. There is a spectrum of morphological patterns of MI. Still, their number and features vary according to the scientific literature, with a certain overlap that creates difficulties and controversies in the precise assessment of MI depth. The purpose of this review is to present and discuss the most important and recent information about patterns of MI, focusing on the more aggressive and the elongated and fragmented glands (MELF) pattern in particular. Assessment of MI depth and correct staging of EC is possible only after the precise recognition of each MI pattern.

Prognostic significance of tumor budding, poorly differentiated cluster, and desmoplastic reaction in endometrioid endometrial carcinomas

AIMS

The tumor budding (TB); poorly differentiated cluster (PDC); desmoplastic reaction (DR); and microcystic, elongated, and fragmented (MELF) patterns of invasion are pathological findings at the tumor invasion front associated with epithelial-to-mesenchymal transition. This study aimed to clarify the clinical significance of the TB, PDC, DR, and MELF patterns in endometrioid endometrial carcinomas (EEC).

METHODS

Two hundred and eight cases of histologically proven EEC retrieved from the archives of the Department of Pathology, Fukui Prefectural Hospital, and diagnosed between January 2000 and August 2020 were retrospectively analyzed.

RESULTS

The TB, PDC, DR, and MELF patterns were identified in 29 (13.9%), 47 (22.6%), 45 (21.6%), and 23 (11.1%) cases, respectively. Kaplan-Meier curve analysis with log-rank test demonstrated that TB, PDC, and DR were associated with a lower progression-free survival (p = 0.010, 0.002, and <0.0001, respectively), whereas the MELF pattern did not show any association (p = 0.668). In multivariate analyses, only DR was significantly associated with lower progression-free survival (p = 0.034). Moreover, only PDC was associated with lower overall survival in univariate analysis (p = 0.018), but the association lost significance in multivariate analysis.

CONCLUSIONS

The present study revealed that the histological confirmation of TB, PDC, and DR at the tumor invasive front predicts poor prognosis in EEC. However, the MELF pattern was not a predictor of poor prognosis in EEC.

Clinicopathologic Association and Prognostic Value of MELF Pattern in Invasive Endocervical Adenocarcinoma (ECA) as Classified by IECC

Microcystic, elongated, and fragmented (MELF) pattern of myometrial invasion is correlated with lymphovascular invasion (LVI) and lymph node metastases in uterine endometrioid carcinoma but has not been described in endocervical adenocarcinoma (ECA). A total of 457 ECAs were collected, and clinical/morphologic parameters correlated with follow-up data. Potential associations between MELF pattern and age, human papillomavirus status, tumor size/grade, LVI, lymph node metastases, Silva pattern were analyzed. Statistical analyses of overall survival (OS), disease-free survival, progression-free survival (PFS) were conducted using Kaplan-Meier analysis, and compared using the Log-rank test. Of 292 ECAs analyzed, 94 (32.19%) showed MELF invasion pattern (MELF-positive). Significant statistical correlation was found between MELF-positive and tumor size (P=0.0017), LVI (P=0.007), Silva pattern (P=0.0005); age, human papillomavirus status, tumor grade, lymph node metastases did not correlate. Fifty-five of 292 patients recurred (18.83%): 18/94 (19.14%) MELF-positive, 37/198 (18.68%) MELF-negative. PFS in MELF-positive: 77.2% and 64.5% at 5 and 10 yr, respectively; PFS in MELF-negative: 82% and 68.5% at 5 and 10 yr, respectively. On multivariate analysis for PFS and other prognostic parameters, only LVI was statistically significant (P=0.001). OS in MELF-positive was 86% and 74.1% at 5 and 10 yr, respectively; OS in MELF-negative, was 89.7% and 86% at 5 and 10 yr, respectively. Median survival was worse in MELF-positive (199.8 mo) versus MELF-negative (226.1 mo); this was not statistically significant. On multivariate analysis for OS and other prognostic parameters, only tumor stage was statistically significant (P=0.002). In ECAs, MELF is not independently associated with survival. Pathologic characteristics of MELF-positive (size, LVI, Silva pattern) versus MELF-negative tumors differ significantly.

[Current WHO classification of the female genitals : Many new things, but also some old]

The new WHO classification of tumors of the female genitalia entails some changes, especially those of prognostic and therapeutic relevance: there is a return to the term borderline tumor. Implants are again subdivided into noninvasive implants of the epithelial or desmoplastic type as before. Invasive extraovarian implants are classified as low-grade serous carcinoma (LGSC). Former seromucinous carcinomas are now classified as endometrioid carcinomas (seromucinous subtype). New entities of ovarian carcinomas are mesonephric-like adenocarcinoma, undifferentiated and dedifferentiated carcinoma, and mixed carcinoma. The classification of neuroendocrine neoplasms is analogous to that of pulmonary and gastrointestinal neuroendocrine neoplasms, regardless of their location. Endometrioid endometrial carcinoma can be classified into four molecular subtypes, which have significant prognostic significance. New subtypes include mucinous carcinoma of the intestinal type and mesonephric-like adenocarcinoma. Stromasarcomas of the endometrium are further subclassified based on specific molecular alterations. Adenocarcinomas (ACs) and squamous cell carcinomas (PECs) of the lower female genital tract are distinguished from HPV-associated and HPV-independent carcinomas. Block-like staining for p16 is the accepted surrogate immunohistochemical marker. Grading has not been reported for PEC. For HPV-associated AC of the cervix uteri, prognostic assessment is based on the pattern of invasion (so-called Silva pattern). Serous carcinomas in the cervix uteri are endometrial carcinomas with cervical infiltration.

Usual-Type Endocervical Adenocarcinoma with a Microcystic, Elongated, and Fragmented Pattern of Stromal Invasion: A Case Report with Emphasis on Ki-67 Immunostaining and Targeted Sequencing Results

The microcystic, elongated, and fragmented (MELF) pattern is a unique myometrial invasion pattern occasionally found at the invasive front of endometrial endometrioid carcinoma (EEC). Herein, we report an uncommon case of usual-type endocervical adenocarcinoma (UEA) with a MELF pattern. We comprehensively analyzed its clinicopathological and molecular features, which has not been previously documented. A 67-year-old woman presented with a cervical mass and underwent radical hysterectomy. Histologically, the MELF pattern of UEA was almost identical to that of EEC. Tumor glands exhibited a microcystic appearance or elongated structures with compression forming a slit-like lumen. The tumor glands were irregularly fragmented into small clusters or single cells. Cells lining the tumor glands possessed conspicuous eosinophilic cytoplasm with squamoid or flattened endothelium-like appearance. These glands or cells were accompanied by a prominent fibromyxoid stromal reaction. Lymphovascular invasion was occasionally observed. Immunostaining revealed diffuse and strong cytokeratin 7 expression and block p16 positivity in both conventional and MELF components. However, the MELF component displayed a very low Ki-67 proliferation index compared to that of the conventional component, which showed markedly increased Ki-67 expression. Targeted sequencing analysis revealed that the MELF component harbored pathogenic mutations in ARID1A, KRAS, and PTEN, identical to those detected in the conventional component. In summary, the morphological features of the MELF pattern in UEA were similar to those in EEC. We found significant differences in Ki-67 expression status between conventional and MELF components, but the mutational profiles were identical. Our findings should be confirmed in larger cohorts of patients with UEA showing a MELF pattern.

POLE mutation combined with microcystic, elongated and fragmented (MELF) pattern invasion in endometrial carcinomas might be associated with poor survival in Chinese women

OBJECTIVE

POLE mutation is a prognostic marker associated with excellent outcome in endometrial carcinoma (EC). However, these EC tumors frequently have aggressive histology. The aim of this study was to determine how to integrate the implications of POLE mutations into existing risk assessment strategies and further stratify patients.

METHODS

We detected POLE mutations in a cohort of 426 ECs from Chinese women and observed their prognostic significance in terms of survival and recurrence outcomes in combination with histological and other molecular characteristics, including microcystic, elongated and fragmented (MELF) pattern invasion, histologic subtype, tumor grade, myometrial invasion and p53 protein and mismatch repair protein expression status.

RESULTS

POLE mutations were identified in 38 of 426 ECs (8.9%). The most common mutations were P286R (31.6%), V411L (15.8%) and Q453R (15.8%). We confirmed that POLE mutation was associated with improved overall survival (P = .047), although it did not show a statistically significant relationship with progression-free survival (P = .45). Interestingly, further analyses indicated that in POLE-mutant tumors, MELF pattern invasion was associated with a 15.1-fold increase in tumor recurrence or progression risk (HR = 15.1, 95%CI = 1.57-145.3, P = .018), whereas this phenomenon was not present in the POLE-wild-type subgroup (HR = 0.90, 95%CI = 0.39-2.08, P = .80). Furthermore, higher staging and deeper myometrial invasion also showed much higher risk in patients harboring POLE mutations compared with those without POLE mutations.

CONCLUSIONS

Although POLE mutation was associated with favorable overall survival, the combined consideration of POLE mutation status and established clinicopathologic factors in the risk assessment of endometrial cancer is more accurate than the consideration of clinicopathologic factors alone and might lead to precise and individualized therapeutic strategies.

Pathological features, immunoprofile and mismatch repair protein expression status in uterine endometrioid carcinoma: focus on MELF pattern of myoinvasion

AIMS

Microcystic, elongated, and fragmented (MELF) pattern of myoinvasion has been related with increased risk of lympho-vascular space invasion (LVSI) and lymph node metastasis. We analysed a cohort of endometrioid endometrial carcinomas (EECs) to examine the relationships between the MELF pattern of invasion and the clinico-pathological and immunohistochemical features of EEC.

METHODS AND RESULTS

129 EECs were evaluated for the presence of MELF pattern and immunohistochemically tested for Mismatch repair (MMR) proteins, p16, p53 and beta-catenin. We observed 28 MELF + EECs and 101 MELF- EECs. LVSI was observed in 20 MELF + cases and in MELF- tumors. Lymph-node metastases were observed in 7 MELF + cases (2 macrometastases, 3 micrometastases and 2 ITCs). None of the MELF- cases showed micrometastases or ITCs, 18 cases had macrometastatic lymph-nodes. Statistical analysis showed that MELF + tumors carry an increased risk of developing nodal metastasis independent of tumor dimension and LVSI. Loss of MMR proteins expression was observed in 11 MELF + cases and 45 MELF- cases, respectively. Our data showed a higher frequency of immunohistochemical MLH1-PMS2 loss in MELF- pattern of invasion (32.67% of MELF- cases vs 21.43% of MELF + cases) but a higher prevalence of MSH2-MSH6 loss in MELF + pattern (7.14% in MELF + population vs 3.96% of MELF- population) CONCLUSIONS: The morphological recognition of MELF pattern is more reliable than immunohistochemical and molecular signatures of EEC in predicting the risk of nodal involvement. The observed higher prevalence of MSH2-MSH6 loss in MELF + group and MLH1-PMS2 loss in MELF- group may suggest a different molecular signature.

Malignant peritoneal cytology and decreased survival of women with stage I endometrioid endometrial cancer

BACKGROUND

To examine the association between malignant peritoneal cytology and survival in women with early-stage endometrioid endometrial cancer.

METHODS

This is a retrospective cohort study using the Surveillance, Epidemiology, and End Results Program from 2010 to 2016. Women with stage I endometrioid endometrial cancer who had peritoneal cytology testing at hysterectomy were examined (N = 24,800). Characteristics and survival related to malignant peritoneal cytology were assessed. The propensity score inverse probability of treatment weighting was used to balance the measured covariates.

FINDINGS

Malignant peritoneal cytology was reported in 1081 (4.4%) women. In multivariable analysis, stage IB disease and moderately/poorly differentiated tumours were associated with an increased likelihood of malignant peritoneal cytology (both P < 0.05). In a weighted model, malignant peritoneal cytology was associated with decreased cause-specific survival (5-year rates, 92.1% versus 96.8%, hazard ratio [HR] 1.98, 95% confidence interval [CI] 1.56-2.52) and overall survival (89.4% versus 93.1%, HR 1.41, 95% CI 1.16-1.72). In sensitivity analyses, malignant peritoneal cytology was associated with decreased overall survival in the high-intermediate-risk group (5-year rates, 77.8% versus 83.6%, HR 1.57, 95% CI 1.20-2.06) and decreased cause-specific survival in the low-risk group (95.4% versus 98.0%, HR 1.64, 95% CI 1.01-2.68). In the high-intermediate-risk group with malignant peritoneal cytology, postoperative chemotherapy was associated with improved overall survival compared to whole pelvic radiotherapy (5-year rates, 82.7% versus 64.6%, HR 0.36, 95% CI 0.14-0.96). This association was not observed in negative cytology cases (81.5% versus 79.7%, HR 0.78, 95% CI 0.53-1.14).

INTERPRETATION

Malignant peritoneal cytology may be associated with decreased survival in stage I endometrioid endometrial cancer.

Microcystic, Elongated and Fragmented Pattern Invasion Can Adversely Influence Preoperative Staging for Low-grade Endometrial Carcinoma

Purpose:

To investigate the influence of microcystic, elongated and fragmented (MELF) pattern invasion on preoperative evaluation of lymph node (LN) metastasis and myometrial invasion in patients with low-grade endometrial carcinoma.

Methods:

The study included 192 consecutive patients with low-grade endometrial carcinoma who underwent preoperative computed tomography (CT) and magnetic resonance imaging (MRI), followed by surgery. One hundred sixty one of 192 patients underwent LN dissection and were analyzed for LN metastasis. All patients were analyzed for myometrial invasion. Presence of enlarged LN was evaluated by using size criteria on CT. Depth of myometrial invasion was evaluated on MRI using T₂-weighted imaging, diffusion-weighted imaging and contrast-enhanced T₁-weighted imaging comprehensively. Sensitivity and specificity for LN metastasis and deep myometrial invasion were evaluated for MELF group and non-MELF group. The difference of sensitivity between two groups was compared using Chi-square and Fisher’s exact test.

Results:

MELF pattern invasion was identified in 43/192 patients (22%). LN metastases were observed in 18/39 patients in MELF group and 6/122 patients in non-MELF group for pelvic LN and 11/29 patients in MELF group and 4/57 patients in non-MELF group for para-aortic LN. Sensitivity for the detection of pelvic LN metastasis in MELF group was significantly lower than in non-MELF group (16.7% vs 66.7%). As for the assessment of the deep myometiral invasion, pathological deep myometrial invasion were found in 31/43 patients in MELF group and 32/149 patients in non-MELF group. Sensitivity in MELF group showed lower values than in non-MELF group (54.8% vs 78.1% for reader 1, 54.8% vs 62.5% for reader 2), although there was no statistically significant difference (P = 0.09 for reader 1 and P = 0.72 for reader 2).

Conclusion:

In case of low-grade endometrial carcinoma with MELF pattern invasion, preoperative staging by CT and MRI have a risk for underestimation.

Myoinvasive Pattern as a Prognostic Marker in Low-Grade, Early-Stage Endometrioid Endometrial Carcinoma

Low-grade and early Federation for Gynecology and Obstetrics (FIGO) stage endometrioid endometrial carcinomas (EEC) have an excellent prognosis. However, approximately 10% of patients develop recurrence, which cannot be correctly predicted at diagnosis. We evaluated myoinvasive patterns as a prognostic factor of relapse in low-grade, early-stage EEC. Two-hundred and fifty-eight cases were selected according to the following inclusion criteria: (i) endometrioid endometrial carcinomas, (ii) grade 1 or 2 with (iii) FIGO stage I or II, and (iv) clinical follow-up. Slides were reviewed to annotate the myoinvasive pattern present in each case (infiltrative glands, microcystic, elongated and fragmented -MELF-, broad front, adenomyosis-like and adenoma malignum). Microsatellite instability was studied by immunoexpression of mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6). There were 29 recurrences (11.2%) among the 258 cases analysed. A predominant broad front myoinvasive pattern was significantly associated with tumour relapse (p = 0.003). The presence of a pattern of infiltrative glands (p = 0.001) and microsatellite instability (p = 0.004) were associated with lower disease-free survival, without having an impact on overall survival. Our observations suggest the potential value of the pattern of myoinvasion as a prognostic factor in low-grade, early-stage endometrioid endometrial carcinoma.

High Expression of Galectin-1, VEGF and Increased Microvessel Density Are Associated with MELF Pattern in Stage I-III Endometrioid Endometrial Adenocarcinoma

Background

In this study, we investigate the expression of markers of angiogenesis and microvessel density (MVD) in cases of microcystic, elongated and fragmented (MELF) pattern, with its prognostic role in the survival of endometrioid endometrial adenocarcinomas (EA) patients.

Methods

In this study, 100 cases of EA, 49 cases with MELF pattern and 51 without, were immunohistochemically stained for galectin-1, vascular endothelial growth factor (VEGF), and MVD. Morphometry and statistical (univariate and multivariate) analyses were performed to assess overall survival (OS) and disease-free survival.

Results

The expression of VEGF (p<.001) and galectin-1 (p<.001), as well as MVD area (p<.001) and number of vessels/mm² (p<.050), were significantly higher in the +MELF pattern group compared to the –MELF group. A low negative correlation between MELF-pattern and the number of days of survival (p<.001, r=–0.47) was also found. A low positive correlation of MELF-pattern with galectin-1 expression (p<.001, r=0.39), area of vessels/mm² (p<.001, r=0.36), outcome of EA (p<.001, r=0.42) and VEGF expression (p<.001, r=0.39) suggests potential pathological relevance of these factors in the prognosis of EA. A univariate survival analysis indicated a role for all parameters of survival. Multivariate Cox proportional hazard regression analysis revealed that only area of vessels/mm² (hazard ratio [HR], 1.018; 95% confidence interval [CI], 1.002 to 1.033), galectin-1 (HR, 1.049; 95% CI, 1.025 to 1.074) and VEGF (HR, 1.049; 95% CI, 1.022 to 1.077) play key roles in OS.

Conclusions

This study reports an increase in MVD, VEGF and galectin-1 expression in EA with MELF pattern and suggests that MELF pattern, along with the angiogenic profile, may be a prognostic factor in EA.

Pathologic Prognostic Factors in Endometrial Carcinoma (Other Than Tumor Type and Grade)

Although endometrial carcinoma (EC) is generally considered to have a good prognosis, over 20% of women with EC die of their disease, with a projected increase in both incidence and mortality over the next few decades. The aim of accurate prognostication is to ensure that patients receive optimal treatment and are neither overtreated nor undertreated, thereby improving patient outcomes overall. Patients with EC can be categorized into prognostic risk groups based on clinicopathologic findings. Other than tumor type and grade, groupings and recommended management algorithms may take into account age, body mass index, stage, and presence of lymphovascular space invasion. The molecular classification of EC that has emerged from the Cancer Genome Atlas (TCGA) study provides additional, potentially superior, prognostic information to traditional histologic typing and grading. This classifier does not, however, replace clinicopathologic risk assessment based on parameters other than histotype and grade. It is envisaged that molecular and clinicopathologic prognostic grouping systems will work better together than either alone. Thus, while tumor typing and grading may be superseded by a classification based on underlying genomic abnormalities, accurate assessment of other pathologic parameters will continue to be key to patient management. These include those factors related to staging, such as depth of myometrial invasion, cervical, vaginal, serosal surface, adnexal and parametrial invasion, and those independent of stage such as lymphovascular space invasion. Other prognostic parameters will also be discussed. These recommendations were developed from the International Society of Gynecological Pathologists Endometrial Carcinoma project.

Clinical and ultrasound characteristics of the microcystic elongated and fragmented (MELF) pattern in endometrial cancer according to the International Endometrial Tumor Analysis (IETA) criteria

Objectives

To describe sonographic features of the microcystic elongated and fragmented (MELF) pattern of myometrial invasion (MI) using the International Endometrial Tumor Analysis (IETA) criteria; to assess the effect of the MELF pattern on preoperative ultrasound evaluation of MI; and to determine the relationship of the MELF pattern to more advanced stage (≥ IB) and lymph node metastases in women with endometrioid endometrial cancer.

Methods/materials

We included 850 women with endometrioid endometrial cancer from the prospective IETA 4 study. Ultrasound experts performed all ultrasound examinations, according to the IETA protocol. Reference pathologists assessed the presence or absence of the MELF pattern. Sonographic features and accuracy of ultrasound assessment of MI were compared in cases with the presence and the absence of the MELF pattern. The MELF pattern was correlated to more advanced stage (≥IB) and lymph node metastases.

Results

The MELF pattern was present in 197 (23.2%) women. On preoperative ultrasound imaging the endometrium was thicker (p = 0.031), more richly vascularized (p = 0.003) with the multiple multifocal vessel pattern (p < 0.001) and the assessment of adenomyosis was more often uncertain (p < 0.001). The presence or the absence of the MELF pattern did not affect the accuracy of the assessment of MI. The MELF pattern was associated with deep myometrial invasion ≥ 50% (p < 0.001), cervical stromal invasion (p = 0.037), more advanced stage (≥ IB) (p < 0.001) and lymph node metastases (p = 0.011).

Conclusions

Tumors with the MELF pattern were slightly larger, more richly vascularized with multiple multifocal vessels and assessment of adenomyosis was more uncertain on ultrasound imaging. The MELF pattern did not increase the risk of underestimating MI in preoperative ultrasound staging. Tumors with the MELF pattern were more than twice as likely to have more advanced stage (≥ IB) and lymph node metastases.

Active K-RAS induces the coherent rotation of epithelial cells: A model for collective cell invasion in vitro

At the invasive front of adenocarcinomas, single cells and multicellular structures exist; the latter include glands and cell clusters, such as tumor buddings and poorly differentiated clusters. Recent reports suggest the importance of collective cell migration in metastasis; however, it is technically difficult to observe the movement of multicellular structures in vivo. We utilized MDCK cells as a model for epithelial cells and established a method to quantify their motility in 3D structures in vitro. A single MDCK cell grows as a cell cluster in the gel and later proliferates and forms a cyst. Active K-RAS expression induced rotation of both the cell clusters and the cysts. The rotation speed of cell clusters was 4 times higher than that of cysts. The screening of inhibitors for their effects on cell clusters and cysts revealed that cyclin B1 and β-catenin were the key molecules for their rotation, respectively. Regulators for cyst rotation, such as vorinostat and β-catenin, were not effective for inducing cell cluster rotation. These results indicate that the signaling pathways of cell dynamics are different between cell clusters and cysts. As cell clusters are related to lymph node involvement and the prognosis of various carcinomas, our in vitro quantitative system may be useful for the screening of drugs to prevent lymphatic invasion.

MELF pattern of myometrial invasion and role in possible endometrial cancer diagnostic pathway: A systematic review of the literature

Microcystic, elongated, fragmented (MELF) pattern of myometrial invasion has been proposed as a prognostic marker in patients with endometrial carcinoma (EC). Its prognostic and predictive effect still remains elusive. The aim of the present study is to accumulate the current knowledge on the role of MELF pattern in the prognosis and survival of patients with EC. Medline, Scopus, Google Scholar, and Clinicaltrials.gov databases were searched for articles published up to May 2018, along with the references of all articles. Prospective and retrospective trials reporting outcomes of cases with EC who were examined for MELF pattern were considered eligible for inclusion in the present systematic review. Of the 196 records screened, 14 were considered eligible. A total of 14 studies which comprised 588 women were finally included in the present systematic review. All the included patients were evaluated for presence of MELF pattern of myometrial invasion. MELF positive (+) patients were more likely to present with larger and higher grade tumors, lymph node metastasis, lymphovascular invasion and >50% myometrial invasion. No difference was reported in disease free survival (DFS) and disease specific survival (DSS) as well as in vaginal recurrence rates. MELF (+) was reported as a significant indicator of survival. In conclusion, MELF pattern of myometrial invasion plays a critical role in lymphovascular space invasion and lymph node metastasis in patients with EC. Regardless, its implication in survival and recurrences is ill determined.

Non-endometrioid and high-grade endometrioid endometrial cancers show DNA fragmentation factor 40 (DFF40) and B-cell lymphoma 2 protein (BCL2) underexpression, which predicts disease-free and overall survival, but not DNA fragmentation factor 45 (DFF45) underexpression

Background

The expression of DNA fragmentation factor 45 (DFF45) and B-cell lymphoma 2 (BCL2) in glands of the normal human endometrium is related to phases of the menstrual cycle and decreases after menopause, whereas the expression of DNA fragmentation factor 40 (DFF40) is stable. Moreover, DF45, BCL2 and DFF40 underexpression has been reported in numerous malignancies, including uterine leiomyosarcomas. In this study, we aimed to investigate DFF45, BCL2 and DFF40 expression in endometrioid and non-endometrioid types of endometrial cancers (ECs). We also evaluated the correlations between DFF45, BCL2 and DFF40 expression levels and clinicopathological parameters and determined the value of these three proteins as prognostic markers of disease-free survival (DFS) and overall survival (OS).

Methods

Immunohistochemistry was performed to evaluate DFF45, BCL2 and DFF40 expression in 342 cases of ECs. Student’s t-test, the Mann-Whitney U-test, and the chi-squared test were used for the statistical analyses as appropriate. The Cox-Mantel test, Cox’s proportional hazard model, and relative risk analyses were used to evaluate associations between DFF40, DFF45, and BCL2 expression and clinicopathological characteristics.

Results

DFF40 and BCL2, but not DFF45, were significantly underexpressed in non-endometrioid and high-grade endometrioid ECs compared with low- and moderate-grade endometrioid ECs. Women with DFF40- and BCL2-negative tumors had higher risks of disease recurrence, lymph node involvement, lympho-vascular space infiltration, and deep myometrial invasion compared with women with DFF40- and BCL2-positive tumors. Additionally, women with DFF40- and BCL2-negative tumors had significantly lower OS and DFS than women with DFF40- and BCL2-positive tumors. A multivariable analysis of the model, including the clinicopathological characteristics and immunohistochemical results, showed that negative BCL2 expression, lymph node involvement, and high-stage and high-grade disease were independent predictors of OS, whereas negative BCL2 expression, lymph node involvement, and high-stage disease were independent predictors of DFS.

Conclusions

Compared with low- and moderate-grade endometrioid ECs, non-endometrioid and high-grade endometrioid ECs showed significant DFF40 and BCL2 underexpression. The absence of DFF40 and BCL2 expression negatively affects DFS and OS. Further prospective studies are warranted to assess the potential utility of DFF40 and BCL2 as targets in the diagnosis or treatment of ECs.

[MELF pattern in myometrial infiltration in endometrioid adenocarcinoma of the endometrium. A retrospective study of 70 cases]

INTRODUCTION

Endometrioid adenocarcinoma of the endometrium (EAE) usually has a favorable prognosis. Recently, the MELF (microcystic, elongated and fragmented) pattern of myometrial infiltration has been described. It is associated with lymphovascular invasion and lymph node metastasis. Seventy cases of EAE were reviewed to identify the presence of MELF and its correlation with other prognostic factors.

MATERIAL AND METHODS

Hysterectomies performed for EAE during a 5-year period were reviewed, searching for MELF pattern. Its presence was correlated with other variables such as histological grade, depth of myometrial infiltration, pelvic and/or aortic lymph node metastasis, peritoneal implants and evolution.

RESULTS

In 17 (24%) cases MELF pattern was detected. It was more frequent in low grade tumors; it was present in four grade 3 cases. In 9 (53%) cases there was deep myometrial infiltration. Five cases had lymph node metastasis in the pelvis and three in the para-aortic region. One of the patients died, another presented a vulvar recurrence and another pulmonary metastasis.

CONCLUSION

MELF pattern can be seen in high grade EAE and correlates with deep myometrial infiltration and pelvic lymph node metastasis. Its presence does not seem to influence survival.

Pathologic Staging of Endometrial Carcinomas: Selected Areas of Difficulty

Accurate staging of cancers is an important determinant of prognosis and guides optimal patient treatment. Although the International Collaboration on Cancer Reporting recommends that endometrial cancers (including carcinosarcomas) are pathologically staged using the International Federation of Gynecology and Obstetrics (FIGO) 2009 system, in many areas TNM [American Joint Committee on Cancer (AJCC) or Union for International Cancer Control (UICC)] staging is used or even mandated; these latter systems are based on FIGO 2009. In this review, areas of difficulty in the pathologic staging of endometrial carcinomas are covered with practical advice for the reporting pathologist. These include issues regarding the assessment of the depth of myometrial involvement (which may be rendered difficult due to a variety of factors), tumor involvement of adenomyosis, and assessment of cervical and uterine serosal involvement. Although not included in the FIGO staging system, the issue of lymphovascular space invasion (LVSI) is covered as this is of prognostic importance and there are multiple problems in the pathologic assessment of this. One important point is that tumors should not be upstaged based on the presence of LVSI alone without tissue involvement; for example, the presence of LVSI in the outer half of the myometrium or in cervical or adnexal vessels in a carcinoma with myoinvasion confined to the inner half of the myometrium is still FIGO stage IA. The issue of simultaneously occurring tumors of the endometrium and adnexa is also covered with advice on how to distinguish between synchronous independent and metastatic neoplasms of both endometrioid and nonendometrioid types. Recent molecular evidence showing that simultaneously occurring endometrioid carcinomas of the endometrium and ovary are clonal and thus probably represent metastatic disease from the endometrium to the ovary rather than synchronous independent neoplasms, as is widely assumed, is discussed.

Disseminated tumor cells are not associated with established risk factors, L1CAM immunoreactivity and outcome in endometrial carcinoma

PURPOSE

The presence of disseminated tumor cells (DTC) in the bone marrow of endometrial carcinoma patients has been demonstrated previously. In contrast to breast cancer, no prognostic significance or association with clinicopathological features was revealed for endometrial carcinoma so far. The aim of this study was to investigate DTC in a large patient cohort with in-depth pathology review data available and to study DTC occurrence in the context of L1CAM and long-term disease specific follow-up.

METHODS

Patients treated for endometrial carcinoma at the Tuebingen University Women's hospital between 2003 and 2013 were identified. Cases with previous expert central pathology review including L1CAM immunohistochemistry and bone marrow aspirates available were selected. The presence of DTC and L1CAM expression was studied immunohistochemically.

RESULTS

In 395 cases with a confirmed diagnosis of endometrial carcinoma, bone marrow aspirates were available. DTC were detected in 17.2%. The presence of DTC was independent from tumor histology, grade, lymphovascular space involvement (LVSI), FIGO stage, myoinvasion, L1CAM immunoreactivity, and nodal metastasis. DTC occurred less frequently in cases with a microcystic elongated and fragmented (MELF) pattern of invasion (2.2 vs. 21.8%, p = 0.0003). Disease progression was distributed equally among patients with and without DTC present.

CONCLUSIONS

We were able to confirm previous findings of DTC presence in a large well-characterized cohort of endometrial carcinoma patients. DTC are detectable in almost one-fifth of endometrial carcinoma and occur less frequently with a MELF pattern of invasion. Further studies investigating the role of DTC in endometrial carcinoma are warranted.