Pathologic and molecular features of uterine carcinosarcomas

Uterine carcinosarcomas: A case series of 9 cases from a low-income country

RATIONALE

Uterine carcinosarcomas (UCS) are rare aggressive biphasic tumors classified as a subtype of high-grade uterine carcinomas. However, these tumors have particular histopathological features and clinical behavior with worse prognosis than high-grade uterine carcinomas.

PATIENT CONCERNS

The incidence of UCS is increasing and more studies are required to elucidate their clinical and histopathological characteristics. Herein, we report clinicopathological features of 9 cases of UCS in a low-income country.

DIAGNOSES

We retrospectively collected all cases of UCS at our Pathology Department over a period of 4 years. The diagnosis was performed on formalin-fixed, paraffin-embedded and hematoxylin and eosin-stained surgical specimens.

INTERVENTIONS

Nine surgically treated cases of UCS have been registered, representing 12.67% of all uterine malignancies with a mean age of 58.88 years (range: 50-65 years). Abdominal pain and metrorrhagia were the main clinical presentations. The epithelial component of UCS was often a serous carcinoma (66.66%) and patients presented with large tumors (mean size of 9.24 cm, range of 5-19 cm), with advanced FIGO stages (stages III-IV) in 5/9 patients (55.55%).

OUTCOMES

Follow-up data were available in 5/9 patients among which only 2 were alive 2 and 25 months after the surgical treatment (overall survival of 40%).

LESSONS

UCS are rare and aggressive uterine tumors with very poor prognosis especially in low-income countries.

Prognostic significance of heterologous component in carcinosarcoma of the gynecologic organs: a systematic review and meta-analysis

OBJECTIVE

The aim of this study is to determine the histologic presence of heterologous component as a prognostic factor in gynecologic carcinosarcoma through a systematic review and meta-analysis.

METHODS

PubMed, Web of Science, and Embase were searched for publications. Studies that evaluated survival effect of sarcomatous component based on histology in human ovarian or uterine carcinosarcoma were included. Two authors independently reviewed the references based on eligibility criteria and extracted the data including primary tumor site, survival outcome, type of survival outcome, and proportion of each sarcomatous differentiation. The quality of each eligible study was assessed with Newcastle-Ottawa scale. Meta-analysis was conducted using a random-effects model to estimate hazard ratio (HR) and 95% confidence intervals (CIs) of survival outcome for carcinosarcoma with or without heterologous component.

RESULTS

Eight studies including 1,594 patients were identified. Overall proportion of carcinosarcoma with heterologous component was 43.3%. Presence of heterologous component was associated with worse overall survival (HR=1.81; 95% CI=1.15-2.85) but not with pooled recurrence-free survival and disease-free survival (HR=1.79; 95% CI=0.85-3.77). Removing multivariate analysis studies, early-stage studies, ovarian tumor study, or studies with large number of patient samples did not affect the significance between heterologous component and overall survival.

CONCLUSION

Gynecologic carcinosarcoma is histologically a biphasic tumor which comprise of epithelial and mesenchymal components. Our study emphasizes pathologic evaluation of heterologous component as a prognostic factor in gynecologic carcinosarcoma when all stages were considered.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42022298871.

Inter‑component immunohistochemical assessment of proliferative markers in uterine carcinosarcoma

In the scientific literature, a selected number of reports have investigated the impact of proliferative activity on the development and progression of uterine carcinosarcomas (UC). The aim of the present retrospective study was to compare the immunohistochemical proliferation markers [Ki67, proliferating cell nuclear antigen (PCNA), minichromosome maintenance complex component 3 (MCM3), and topoisomerase IIα (topoIIα)] assessment in both components of UC. A total of 30 paraffin-embedded slides of UCs, obtained from patients who underwent surgery between January 1, 2006, and December 31, 2020, were analyzed. Medical records and clinicopathological data of patients were reviewed. Formalin-fixed, paraffin-embedded tissue sections were immunostained with monoclonal antibodies against Ki67, PCNA, MCM3 and topoIIα. Ki67-positive nuclear immunoreactivity was reported in 20 (67%) and 16 (53%) UC carcinomatous and sarcomatous components, respectively. In the epithelial component, Ki67 positive staining was related to the International Federation of Gynecology and Obstetrics (FIGO) stage (P=0.025), and histological grade (G1 vs. G2/G3, P=0.031). Nuclear PCNA reactivity was observed in 18 (60%) and 16 (53%) carcinomatous and sarcomatous components, respectively. Notably, all four cases with omental metastases were PCNA-positive, and a relationship between staining pattern and the existence of metastases was of significant value (P=0.018). MCM3-positive nuclear staining was found nearly twice as high in the carcinomatous (n=19; 63%), compared with the sarcomatous (n=11; 37%) component, respectively, and MCM3 expression in the epithelial component was related to clinical stage (P=0.030), and the existence of omental metastasis (P=0.012). In addition, out of the 30 UCs, 17 (57%) and 13 (43%) showed topoIIα positivity in the carcinomatous and sarcomatous UC components, respectively. A significant relationship between protein immunoreactivity and FIGO stage (P=0.049), and omental metastasis (P=0.026) was revealed to exist. However, no significant differences between expression of proliferation markers and clinicopathological features in the sarcomatous UC component were identified. Finally, a significant correlation between each protein immunohistochemical staining was demonstrated, particularly in the sarcomatous UC component. Collectively, a combined analysis of Ki67, PCNA, MCM3, and topoIIα may provide more detailed information of cell-cycle alterations determining the heterogeneity of uterine carcinosarcomas.

Comparing paclitaxel-platinum with ifosfamide-platinum as the front-line chemotherapy for patients with advanced-stage uterine carcinosarcoma

BACKGROUND

Uterine carcinosarcoma (UCS) is a rare but highly lethal disease. Adjuvant chemotherapy is highly recommended for advanced UCS. To date, the standard chemotherapy regimen is still uncertain, although two regimens as paclitaxel-platinum (PP) and ifosfamide-platinum (IP) regimens are most commonly used. The aims of the current study attempt to compare both regimens in the management of advanced UCS patients.

METHODS

We evaluated advanced UCS patients who were treated either with PP or with IP after primary cytoreductive surgery in single institute retrospectively. The clinical-pathological parameters, recurrence, and survival were recorded.

RESULTS

A total of 16 patients were analyzed. Twelve patients received adjuvant PP therapy, and the remaining four patients received IP therapy. The median follow-up time was 28 months, ranging from 3.8 months to 121 months. Disease-related death occurred in 10 patients (62.5%). The median progression-free survival was 4.9 months, ranging from 3.8 months to 36.5 months in IP, and 23.1 months, ranging from 9.3 months to 121 months in PP, with statistically significant difference (p = 0.04). The median overall survival was 9.5 months (ranging from 3.8 months to 36.5 months) and 28.7 months (ranging from 10.3 months to 121 months) in IP and PP, respectively, without statistically significant difference (p = 0.06). Presence of pelvic and para-aortic lymphadenopathy and deep myometrial invasion (>1/2) were associated with worse prognosis by univariate analysis. No prognostic factor could be identified using multivariate analysis model.

CONCLUSION

In the current study, due to extremely little number of subjects enrolled, the advantage of using paclitaxel-platinum regimen in the management of advanced UCS was still unclear, although a certain trend of favoring was supposed. We are looking forward to seeing more studies to identify the approximate regimen in the management of this highly lethal disease.

Dynamic contrast-enhanced MR and PET/CT findings of uterine sarcomatoid carcinoma: a case report

Background

Sarcomatoid carcinoma (SC) is a malignant tumour composed of spindle cells. The incidence of SC is low, especially in the uterus. The imaging features of uterine sarcomatoid carcinoma (USC) are rarely reported. We report a case of USC and discuss the dynamic contrast-enhanced MR (DCE-MR) and PET/CT findings.

Case presentation

A 69-year-old woman presented to the Department of Gynaecology with vaginal bleeding. Ultrasound examination discovered a heterogeneous mass in the cervix. Then, MRI examination of the pelvis was performed. On T2-weighted images, the uterus was replaced by an ill defined and diffuse lesion with inhomogeneous intensity. On T1-weighted images, the lesion appeared with signal hypointensity and was heterogeneously enhanced with contrast material. Additionally, enlarged lymph nodes were found in the pelvic cavity. PET/CT demonstrated high uptake in the region of the uterus and pelvic lymph nodes, which was consistent with MRI findings. The radiologists diagnosed the patient with malignant uterine lesions. The patient underwent hysterectomy and bilateral adnexectomy with pelvic lymph node dissection. Then, systemic radiotherapy and chemotherapy were performed. USC with lymph node metastasis was diagnosed with the help of immuno-histochemical analysis. There was no treatment related complication and no evidence of tumour recurrence at the postoperative 6-month follow-up.

Conclusion

MRI and PET/CT features are sufficient to indicate the malignant nature of a USC, but they are not pathognomonic.

Cytologic features of undifferentiated and dedifferentiated carcinomas of the endometrium

BACKGROUND

Undifferentiated carcinoma (UC) is a rare, aggressive subtype of endometrial carcinoma. Dedifferentiated carcinomas (DCs) are UCs associated with a component of well differentiated endometrioid carcinoma. The authors sought to describe the morphologic features of UCs and DCs in cytologic specimens.

METHODS

Cytologic specimens from 23 women (aged 46-86 years; median age, 59 years) were reviewed, including cervicovaginal specimens (n = 7), peritoneal washings (n = 5), touch preparations of core biopsies from various sites (n = 5), fine-needle biopsies of lymph nodes (n = 3), ascitic fluid (n = 1), pleural fluid (n = 1), and intrauterine fluid (n = 1).

RESULTS

There were 10 UCs (43%) and 13 DCs (57%). Tumor cells were arranged as single cells (9 UCs, 90%; 12 DCs, 92%) and 3-dimensional groups (8 UCs, 80%; 11 DCs, 85%). Most cases showed high nuclear-to-cytoplasmic ratios. Nuclear molding was observed in 3 UCs (30%) and in 5 DCs (38%). Nuclear chromatin was often coarsely granular 6 UCs, 60%; 9 DCs, 69%). Nucleoli were inconspicuous in some cases (6 UCs, 60%; 8 DCs, 62%) but were appreciable in others. Necrosis was observed in 5 UCs (50%) and in 5 DCs (38%). Most cases exhibited clean backgrounds, and a few showed acute inflammation. Comparison of the cytologic features of UCs and DCs did not reveal any statistically significant differences.

CONCLUSIONS

UCs and DCs have a spectrum of cytomorphologic appearances that are not pathognomonic, but the presence of some of these (relatively uniform population of predominantly singly dispersed cells with high nuclear-to-cytoplasmic ratios and variably conspicuous nucleoli) should prompt consideration of UC and DC in the differential diagnosis.

MLH1 promoter hypermethylation in uterine carcinosarcoma rarely coexists with TP53 mutation

Introduction

Carcinosarcoma (CS) is an infrequent neoplasm composed of a carcinomatous and a sarcomatous element. Its molecular pathogenesis is poorly understood. In this study, we investigated the disturbances in the immunohistochemical expression of p53 and mismatch repair (MMR) proteins, as well as their molecular background.

Material and methods

The study group consisted of 20 uterine CSs. We analysed their morphology and immunohistochemical expression of hMLH1, hPMS2, hMSH2, MSH6, and p53 as well as the presence of mutations in TP53 and promoter methylation of the hMLH1. Loss of hMLH1 and PMS2 was found in 3/20 tumours. All cases were positive for hMSH2 and hMSH6. The TP53 mutation was detected in 8/19 tumours (42.1%), whereas MLH1 promoter hypermethylation in 4/19 cases (21%), and one case with synchronous aberrations (5%). Agreement between the results of the genetic and immunohistochemical study was moderate for p53 (k = 0.615, p< 0.01) and strong for MLH1 (k = 0.826, p< 0.01).

Results and conclusions

We demonstrated MLH1 promoter hypermethylation in uterine CS, leading to loss of MLH1 immunostaining. Concomitant aberrations of p53 and hMLH1 are infrequent. It is likely that uterine CS may develop in two independent molecular pathways in association with either chromosomal or microsatellite instability.

Unique Molecular Features in High-Risk Histology Endometrial Cancers

Endometrial cancer is the most common gynecologic malignancy in the United States and the sixth most common cancer in women worldwide. Fortunately, most women who develop endometrial cancer have low-grade early-stage endometrioid carcinomas, and simple hysterectomy is curative. Unfortunately, 15% of women with endometrial cancer will develop high-risk histologic tumors including uterine carcinosarcoma or high-grade endometrioid, clear cell, or serous carcinomas. These high-risk histologic tumors account for more than 50% of deaths from this disease. In this review, we will highlight the biologic differences between low- and high-risk carcinomas with a focus on the cell of origin, early precursor lesions including atrophic and proliferative endometrium, and the potential role of stem cells. We will discuss treatment, including standard of care therapy, hormonal therapy, and precision medicine-based or targeted molecular therapies. We will also discuss the impact and need for model systems. The molecular underpinnings behind this high death to incidence ratio are important to understand and improve outcomes.

[Un- and dedifferentiated endometrial carcinoma : A rare entity with a wide range of differential diagnosis]

Dedifferentiated endometrial carcinomas (ECs) are composed of undifferentiated EC and a FIGO grade 1 or 2 endometrioid carcinoma. The undifferentiated component represents a malignant epithelial neoplasm with no obvious differentiation and immunohistochemical loss of PAX8, E‑cadherin and focal expression of EMA and/or CK18 and the predominant presence of nuclear staining for INI1 (SMARCB1) and BRG1 (SMARCA4). The main differential diagnoses include poorly differentiated endometrioid EC, neuroendocrine carcinoma, lymphoma, plasmocytoma, high-grade endometrial stromal sarcomas, undifferentiated uterine sarcomas (UUS), carcinosarcomas, and metastases to the endometrium. The histogenesis is not yet fully understood and molecular data are still limited. Some tumors represent a loss of MHL1 and PMS2 staining due to MLH1-promotor methylation. Rare cases are associated with Lynch syndrome or POLE mutation. The un- or dedifferentiated EC represents a high-grade endometrial carcinoma that requires extended surgery and indicates a poor prognosis. In cases with mismatch repair protein deficiency or POLE mutation, immuno-oncological treatment with checkpoint inhibitors are a therapeutic option.

Sarcoma of the Uterus. Guideline of the DGGG and OEGGG (S2k Level, AWMF Register Number 015/074, February 2019)

Aims This is an official guideline published and coordinated by the German Society of Gynecology and Obstetrics (DGGG) and the Austrian Society of Gynecology and Obstetrics (OEGGG). Because of their rarity and heterogeneous histopathology, uterine sarcomas are challenging in terms of how they should be managed clinically, and treatment requires a multidisciplinary approach. To our knowledge, there are currently no binding evidence-based recommendations for the appropriate management of this heterogeneous group of tumors. Methods This S2k guideline was first published in 2015. The update published here is the result of the consensus of a representative interdisciplinary group of experts who carried out a systematic search of the literature on uterine sarcomas in the context of the guidelines program of the DGGG, OEGGG and SGGG. Members of the participating professional societies achieved a formal consensus after a moderated structured consensus process. Recommendations The consensus-based recommendations and statements include the epidemiology, classification, staging, symptoms, general diagnostic work-up and general pathology of uterine sarcomas as well as the genetic predisposition to develop uterine sarcomas. Also included are statements on the management of leiomyosarcomas, (low and high-grade) endometrial stromal sarcomas and undifferentiated uterine sarcomas and adenosarcomas. Finally, the guideline considers the follow-up and morcellation of uterine sarcomas and the information provided to patients.

[S3 guidelines on the diagnosis and treatment of carcinoma of the endometrium : Requirements for pathology]

The present article summarises the relevant aspects of the S3 guidelines on endometrioid carcinomas. The recommendations include the processing rules of fractional currettings as well as for hysterectomy specimens and lymph node resections (including sentinel lymph nodes). Besides practical aspects, the guidelines consider the needs of the clinicians for appropriate surgical and radiotherapeutic treatment of the patients. Carcinosarcomas are assigned to the endometrial carcinoma as a special variant. For the first time, an algorithmic approach for evaluation of the tumour tissue for Lynch syndrome is given. Prognostic factors based on morphologic findings are summarised.

Prognostic factors, survival outcomes, and surgical practices when dealing with uterine sarcomas: 8 years’ clinical experience

Objective

To determine the clinical and pathologic characteristics, prognostic factors, surgical practice, adjuvant therapies, and survival outcomes of patients with uterine sarcoma diagnosed and treated in our institution.

Material and Methods

Patients diagnosed and treated for uterine sarcomas at our institution from 2009 to 2017 were retrospectively evaluated. All histologic slides from the specimens underwent a thorough pathologic review by a gynecologic pathologist. The following variables were assessed: age, family history of cancer, smoking status, age of menarche, parity, age at first delivery, related symptoms, clinical staging, histologic type, treatment received, disease-free period, and the time and site of recurrence, as well as treatment of the latter and overall survival.

Results

Ten patients were diagnosed as having leiomyosarcoma, a further 10 patients had malignant mixed mullerian tumors, and five had endometrial stromal sarcoma; the remaining nine patients had other tumors. At the end of our study, 12 (35.3%) patients were alive and in remission, four (11.8%) were alive with disease, 10 (29.4%) were lost to follow-up, and eight (23.5%) had died. The mean survival time was 80.92 months, and the 2-year survival rate was 75.6%. We found that survival was significantly shorter in the presence of lymph node involvement, residual tumor, and recurrence.

Conclusion

This study serves to inform physicians about the outcome of various uterine sarcomas that were diagnosed and managed at our center. We found that 35.3% of our patients were alive and in remission, 11.8% were alive with disease, 29.4% were lost to follow-up, and 23.5% of patients died.

High-grade Endometrial Carcinomas: Morphologic and Immunohistochemical Features, Diagnostic Challenges and Recommendations

This review of challenging diagnostic issues concerning high-grade endometrial carcinomas is derived from the authors' review of the literature followed by discussions at the Endometrial Cancer Workshop sponsored by the International Society of Gynecological Pathologists in 2016. Recommendations presented are evidence-based, insofar as this is possible, given that the levels of evidence are weak or moderate due to small sample sizes and nonuniform diagnostic criteria used in many studies. High-grade endometrioid carcinomas include FIGO grade 3 endometrioid carcinomas, serous carcinomas, clear cell carcinomas, undifferentiated carcinomas, and carcinosarcomas. FIGO grade 3 endometrioid carcinoma is diagnosed when an endometrioid carcinoma exhibits >50% solid architecture (excluding squamous areas), or when an architecturally FIGO grade 2 endometrioid carcinoma exhibits marked cytologic atypia, provided that a glandular variant of serous carcinoma has been excluded. The most useful immunohistochemical studies to make the distinction between these 2 histotypes are p53, p16, DNA mismatch repair proteins, PTEN, and ARID1A. Endometrial clear cell carcinomas must display prototypical architectural and cytologic features for diagnosis. Immunohistochemical stains, including, Napsin A and p504s can be used as ancillary diagnostic tools; p53 expression is aberrant in a minority of clear cell carcinomas. Of note, clear cells are found in all types of high-grade endometrial carcinomas, leading to a tendency to overdiagnose clear cell carcinoma. Undifferentiated carcinoma (which when associated with a component of low-grade endometrioid carcinoma is termed "dedifferentiated carcinoma") is composed of sheets of monotonous, typically dyscohesive cells, which can have a rhabdoid appearance; they often exhibit limited expression of cytokeratins and epithelial membrane antigen, are usually negative for PAX8 and hormone receptors, lack membranous e-cadherin and commonly demonstrate loss of expression of DNA mismatch repair proteins and SWI-SNF chromatin remodeling proteins. Carcinosarcomas must show unequivocal morphologic evidence of malignant epithelial and mesenchymal differentiation.

Issues in the Differential Diagnosis of Uterine Low-grade Endometrioid Carcinoma, Including Mixed Endometrial Carcinomas: Recommendations from the International Society of Gynecological Pathologists

This article provides practical recommendations developed from the International Society of Gynecological Pathologists Endometrial Carcinoma Project to address 4 issues that may arise in the diagnosis of uterine corpus low-grade endometrioid carcinoma: (1) The distinction between atypical hyperplasia and low-grade endometrioid carcinoma. (2) The distinction between low-grade endometrioid carcinoma and serous carcinoma. (3) The distinction between corded and hyalinized or spindle cell variants of low-grade endometrioid carcinoma and carcinosarcoma. (4) The diagnostic criteria for mixed endometrial carcinomas, a rare entity that should be diagnosed only after exclusion of a spectrum of tumors including morphologic variants of endometrioid carcinoma, dedifferentiated endometrial carcinoma, carcinosarcoma, and endometrial carcinomas with ambiguous morphology.

Expression of p53 and PTEN in human primary endometrial carcinomas: Clinicopathological and immunohistochemical analysis and study of their concomitant expression

Endometrial carcinoma is a common malignancy of the female genital tract. Alterations in the expression levels of various oncogenes and tumor suppressor genes serve important roles in the carcinogenesis and biological behavior of endometrial carcinoma. The aim of the present study was to evaluate the combination and individual expression of p53 and phosphatase and tensin homolog (PTEN) protein in human endometrial carcinoma. In addition, the correlation of these proteins with clinicopathological parameters was also assessed. Retrospective immunohistochemical analysis of the expression of p53 and PTEN tumor suppressor proteins was conducted in 99 women with endometrial carcinoma. The overall rate of p53 and PTEN positivity was 89 and 77%, respectively, according to the sum of stain intensity and scores of immunopositive cells. The sum of p53 positivity correlated strongly with PTEN expression (ρ=0.256; P=0.044). The concomitant sum of p53 and PTEN expression was identified in 45% of patients with endometrial adenocarcinoma. Notably, the sum of the immunohistochemical expression of p53 was significantly correlated with patient age (P=0.037), histologic type (P=0.008), histologic grade (P=0.002) and fallopian and/or ovarian invasion (P=0.014). Furthermore, PTEN expression was associated with myometrial invasion (ρ=−0.377; P=0.002) and clinical stage (P=0.019). In addition, concomitant p53 and PTEN expression was correlated with patient age (P=0.008) and histologic differentiation (P=0.028). The findings indicated a correlation between the expression of p53 and PTEN in endometrial adenocarcinoma, which suggested an intrinsic association between expression levels of these tumor suppressor genes. The study also suggested that concomitant p53 and PTEN expression contributed in characterizing the tumor behavior of endometrial carcinoma. Taken together, the present study suggested the combined expression of p53 and PTEN in the development of high-grade endometrial carcinoma in older patients. In addition, the findings indicated activation of different molecular pathways in the tumor progression between low-grade and high-grade endometrial carcinomas.

When Is "Type I" Ovarian Cancer Not "Type I"? Indications of an Out-Dated Dichotomy

The dualistic classification of epithelial ovarian cancer (EOC) into “type I” and “type II” is widely applied in the research setting; it is used as a convenient way of conceptualizing different mechanisms of tumorigenesis. However, this classification conflicts with recent molecular insights of the etiology of EOC. Molecular and cell of origin studies indicate that while type II tumors could be classed together, type I tumors are not homogenous, even within the histological types, and can have poor clinical outcomes. Type II high grade serous carcinoma and type I low grade serous carcinomas best fit the description of the dualistic model, with different precursors, and distinct molecular profiles. However, endometriosis-associated cancers should be considered a separate group, without assuming an indolent course or type I genetic profiles. Furthermore, the very clear differences between mucinous ovarian carcinomas and other type I tumors, including an uncertain origin, and heterogeneous mutational spectrum and clinical behavior, indicate a non-type I classification for this entity. The impression that only type II carcinomas are aggressive, have poor prognosis, and carry TP53 mutations is an unhelpful misinterpretation of the dualistic classification. In this review, we revisit the history of EOC classification, and discuss the misunderstanding of the dualistic model by comparing the clinical and molecular heterogeneity of EOC types. We also emphasize that all EOC research, both basic and clinical, should consider the subtypes as different diseases beyond the type I/type II model, and base novel therapies on the molecular characteristics of each tumor.

p53 aberrations in low grade endometrioid carcinoma of the endometrium with nodal metastases: possible insights on pathogenesis discerned from immunohistochemistry

Background

TP53 mutations are rarely identified in low grade endometrioid carcinoma of the endometrium, and their pathogenic significance in such tumors is evidenced by the fact that TP53 aberrations have been associated with reduced recurrence-free survival in this subset of tumors. However, TP53 aberrations may not always represent a driving molecular event in a given endometrial cancer with a mutation. In this case study, the immunophenotype of a distinctive low grade endometrioid adenocarcinoma with an unusual pattern of lymph node metastases is used to explore the possible roles for underlying TP53-related molecular events in its pathogenesis.

Case presentation

A low grade endometrioid carcinoma, 9 cm in greatest dimension, with 35% invasion of the myometrial wall thickness, focal lymphovascular invasion, and metastases to 2 of 16 pelvic lymph nodes, was diagnosed in a 52-year-old woman. The endometrial tumor showed a p53-mutation (aberrant)-type immunohistochemical pattern in 40% of the tumor, but the rest of the tumor, as well as the foci of myometrial and lymphovascular invasion, were p53-wild type. Both lymph nodes with metastatic disease showed a distinct biphasic pattern, comprised of both p53-wild type and p53-aberrant areas in tumoral foci that were spatially apposed but not intermixed. Most p53-aberrant areas (at both the lymph nodes and the endometrium) showed a higher mitotic index and increased atypia as compared to the p53-wild type areas; both showed squamous differentiation. The p53-aberrant areas at both locations were also p16-diffusely positive, vimentin-positive, and estrogen/progesterone receptor-positive, whereas the p53-wild type areas showed an identical immunophenotype with the exception of being p16-mosaic positive. All components of the tumor at both the primary and metastatic sites showed loss of MSH2 and MSH6 and retained MLH/PMS2 expression.

Conclusions

The presence of p53-mutant and wild-type areas in multiple lymph nodes, coupled with the absence of a p53-aberrant immunophenotype in the myometrium-invasive or lymphovascular-invasive portions of the tumor, argues against the possibility that the TP53 mutation in this tumor is a driving event in its pathogenesis, at least regarding the metastatic process. This case illustrates how routine immunohistochemistry can provide important insights into underlying molecular events in cancers, exemplifies an uncommon co-existence of DNA mismatch repair protein deficiency and p53-aberrant immunophenotype in low-grade endometrioid carcinoma, illustrates morphologic differences between p53-aberrant and p53-wild type areas within in the same tumor, and is an exemplar of the emerging theory that lymph node metastases of endometrial cancer may be comprised of different subclones of the primary tumor.

Fascin Is Associated With Aggressive Behavior and Poor Outcome in Uterine Carcinosarcoma

OBJECTIVE

The mechanisms underlying the histogenesis and aggressiveness of uterine carcinosarcoma (UCS) are poorly understood; however, previous studies implicate epithelial-mesenchymal transition (EMT). Fascin is a proinvasive, actin-bundling protein and an important component of EMT. It is associated with poor outcomes in human carcinoma, especially in estrogen receptor (ER)-negative tumors arising in organs normally expressing ER. We sought to evaluate fascin expression in UCS and its relationship to ER status, clinicopathologic indicators of tumor aggressiveness, and survival outcomes.

METHOD

Forty-four surgically staged cases of UCS were immunohistochemically evaluated for fascin and estrogen receptor-α expression and correlated with clinicopathologic parameters derived from electronic medical records and pathology reports.

RESULTS

Fascin was only expressed in malignant epithelium and mesenchyma and was uniformly absent in background benign counterparts. Increased expression was associated with extrapelvic disease (P = 0.028), higher stage (P = 0.021), larger tumor size (P = 0.032), shorter progression-free interval (P = 0.035), and reduced estrogen receptor-α expression (P = 0.04).

CONCLUSION

Fascin is aberrantly expressed in both elements of UCS and is associated with aggressive behavior and worse outcome. As a component of EMT and mediator of invasion, fascin may serve as a target in future therapies.

[Grading of gynecological tumors : Current aspects]

Histopathological assessment of the tumor grade and cell type is central to the management and prognosis of various gynecological malignancies. Conventional grading systems for squamous carcinomas and adenocarcinomas of the vulva, vagina and cervix are poorly defined. For endometrioid tumors of the female genital tract as well as for mucinous endometrial, ovarian and seromucinous ovarian carcinomas, the 3‑tiered FIGO grading system is recommended. For uterine neuroendocrine tumors the grading system of the gastrointestinal counterparts has been adopted. Uterine leiomyosarcomas are not graded. Endometrial stromal sarcomas are divided into low and high grades, based on cellular morphology, immunohistochemical and molecular findings. A chemotherapy response score was established for chemotherapeutically treated high-grade serous pelvic cancer. For non-epithelial ovarian malignancies, only Sertoli-Leydig cell tumors and immature teratomas are graded. At this time molecular profiling has no impact on the grading of tumors of the female genital tract.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Uterine Tumors

This article focuses on the diagnostic, prognostic, and predictive molecular biomarkers in uterine malignancies, in the context of morphologic diagnoses. The histologic classification of endometrial carcinomas is reviewed first, followed by the description and molecular classification of endometrial epithelial malignancies in the context of histologic classification. Taken together, the molecular and histologic classifications help clinicians to approach troublesome areas encountered in clinical practice and evaluate the utility of molecular alterations in the diagnosis and subclassification of endometrial carcinomas. Putative prognostic markers are reviewed. The use of molecular alterations and surrogate immunohistochemistry as prognostic and predictive markers is also discussed.

miR-200c-driven Mesenchymal-To-Epithelial Transition is a Therapeutic Target in Uterine Carcinosarcomas

Uterine carcinosarcomas (UCSs) are highly aggressive malignancies associated with poor prognoses and limited treatment options. These tumors are hypothesized to develop from the endometrial adenocarcinoma (EAC) through epithelial-mesenchymal transition (EMT). We test this long-standing hypothesis by depleting miR-200, a family of microRNAs critical for EMT, in EAC cell lines. Our data suggest that UCSs do not develop from EACs via EMT. Clinically more relevant, we show that miR-200 expression in UCS cells induces a robust mesenchymal-epithelial transition (MET). Using in vitro and murine xenograft models, we demonstrate decreased growth and aggressiveness of miR-200-overexpressing UCS cell lines. Whole transcriptome analysis confirmed changes consistent with an MET and also revealed changes in angiogenic genes expression. Finally, by treatment of UCS-xenografted mice with miR-200c incorporated in DOPC nanoliposomes, we demonstrate anti-tumor activities. These findings suggest that ectopic miR-200 expression using advanced microRNA therapeutics may be a potential treatment approach for patients with UCS.

Integrated Molecular Characterization of Uterine Carcinosarcoma

We performed genomic, epigenomic, transcriptomic, and proteomic characterizations of uterine carcinosarcomas (UCSs). Cohort samples had extensive copy-number alterations and highly recurrent somatic mutations. Frequent mutations were found in TP53, PTEN, PIK3CA, PPP2R1A, FBXW7, and KRAS, similar to endometrioid and serous uterine carcinomas. Transcriptome sequencing identified a strong epithelial-to-mesenchymal transition (EMT) gene signature in a subset of cases that was attributable to epigenetic alterations at microRNA promoters. The range of EMT scores in UCS was the largest among all tumor types studied via The Cancer Genome Atlas. UCSs shared proteomic features with gynecologic carcinomas and sarcomas with intermediate EMT features. Multiple somatic mutations and copy-number alterations in genes that are therapeutic targets were identified.

Malignant mesenchymal tumors of the uterus - time to advocate a genetic classification

INTRODUCTION

Sarcomas are rare uterine tumors with leiomyosarcomas and endometrial stromal sarcomas constituting the predominant entities often making their first appearance in young and middle-aged women. By histology combined with immunostaining alone some of these tumors can offer diagnostic challenges e.g. for the differential diagnosis between leiomyosarcomas and smooth muscle tumors of uncertain malignant potential (STUMP). Areas covered: Recent advances in the genetic classification and subclassification, respectively, have shown that genetic markers can offer a valuable adjunct to conventional diagnostic tools. Herein, we will review these recent data from the literature also referring to genetic alterations found in STUMP, endometrial stromal nodules, and leiomyomas including their variants. Expert commentary: For the future, we consider genetic classification as a necessary step in the clinical management of these tumors which will help not only to improve the diagnosis but also the therapy of these malignancies often associated with a worse prognosis.

[Dualistic classification of epithelial ovarian cancer: Is it clinically relevant?]

Malignant epithelial tumors (carcinomas) are the most common ovarian cancers and the most lethal gynecological malignancies. Based on their heterogeneous morphology, a dualistic model of carcinogenesis was proposed in 2004. Type I carcinomas, composed of low grade serous, endometrioid, mucinous, clear cell carcinomas and malignant Brenner tumors, were distinct from type II carcinomas (high grade serous, undifferentiated carcinomas and carcinosarcomas). However, clinical studies failed to demonstrate the prognostic value of such a classification. The main reproach to this dualistic model was that it lumped together in type I tumors, heterogeneous lesions such as clear cell and mucinous carcinomas. Recent advances on molecular genetic alterations and precursor lesions favor the classification of ovarian carcinomas as five distinct diseases. The dualistic model of carcinogenesis in type I and II can finally be applied only to serous ovarian carcinomas (low grade and high grade).

A practical approach to the diagnosis of mixed epithelial and mesenchymal tumours of the uterus

The current 2014 World Health Organization (WHO) Classification of mixed epithelial and mesenchymal tumours of the uterus includes categories of carcinosarcoma, adenosarcoma, adenofibroma, adenomyoma and atypical polypoid adenomyoma, the last two lesions being composed of an admixture of benign epithelial and mesenchymal elements with a prominent smooth muscle component. In this review, each of these categories of uterine neoplasm is covered with an emphasis on practical tips for the surgical pathologist and new developments. In particular, helpful clues in the distinction between carcinosarcoma and dedifferentiated endometrial carcinoma will be discussed. In addition, salient features to help distinguish between adenofibroma, adenosarcoma, embryonal rhabdomyosarcoma and other mesenchymal neoplasms in the differential diagnosis will be outlined. Finally, a discussion of adenomyoma and its main differential diagnostic considerations will be covered.

Outcome and prognosis in uterine sarcoma and malignant mixed Mullerian tumor

PURPOSE

There is low evidence regarding the optimal treatment in patients with uterine sarcomas and malignant mixed Mullerian tumors (MMMTs). This study provides an overview of experience at our center with patients diagnosed with uterine sarcoma and MMMT, in relation to the clinical management and outcome.

METHODS

The medical records for 143 patients with low-grade endometrial stromal sarcoma (ESS), leiomyosarcoma (LMS), and high-grade (undifferentiated) endometrial sarcoma (UES) and MMMT were reviewed. All available clinical and pathological data were collected and analyzed. Putative prognostic factors were entered into a multivariate analysis using a Cox proportional hazards ratio model, and survival data were calculated.

RESULTS

The 5-year overall survival rates were significantly different between patients with ESS, LMS, and UES and MMMT (86 vs. 40 vs. 57 vs. 45 %; P < 0.001). The multivariate analysis showed that the patients' age, higher FIGO stage (III-IV), a history of smoking, prior pelvic radiation, diabetes, and residual tumor after surgery were associated with a poorer overall survival. Histological subtypes of LMS (HR 4.68; 95 % CI 1.35-16.17), UES (HR 1.21; 95 % CI 0.26-5.77) and MMMT (HR 1.63; 95 % CI 0.42-6.43) were also associated with a poorer overall survival than ESS (P = 0.008). Adjuvant therapies showed no associations with overall survival.

CONCLUSIONS

Adjuvant therapy has so far not shown any overall survival benefit, and the focus is therefore on primary surgery. In future studies, the entities should be investigated separately in relation to prognostic factors and effective therapeutic management.

Sarcoma of the Uterus. Guideline of the DGGG (S2k-Level, AWMF Registry No. 015/074, August 2015)

Purpose: Official guideline published and coordinated by the German Society of Gynecology and Obstetrics (DGGG). Due to their rarity and their heterogeneous histopathology uterine sarcomas remain challenging tumors to manage and need a multidisciplinary approach. To our knowledge so far there is no evidence-based guideline on the appropiate management of these heterogeneous tumors. Methods: This S2k-guideline is the work of an representative committee of experts from a variety of different professions who were commissioned by the DGGG to carry out a systematic literature review of uterine sarcoma. Members of the participating scientific societies developed a structured consensus in a formal procedure. Recommendations: 1. The incidence and histopathologic classification of uterine sarcoma. 2. The clinical manifestations, diagnosis and staging of uterine sarcoma. 3. The management of leiomyosarcoma. 4. The management of endometrial stromal sarcoma and undifferentiated uterine sarcoma. 5. The management of adenosarcoma as well as carcinosarcomas. 6. The management of morcellated uterine sarcoma.

Immunohistochemical expression of cancer stem cell related markers CD44 and CD133 in endometrial cancer

The goal of this study was to detect the presence of cancer stem cell markers CD44 and CD133 in immunohistochemically stained samples of endometrial cancer and correlate their expression with clinicopathological variables to identify the impact of CD44 or CD133 expression on tumor behavior and endometrial carcinogenesis. Marker expression was analyzed in 62 endometrial cancer samples (57 endometrioid carcinoma and 5 carcinosarcoma) and 15 proliferative endometrium samples. We detected CD133 and CD44 expression in 87.09% and 79.03% respectively of the studied endometrial cancers, and the expression was significantly different from the normal group. CD44 expression decreased with myometrial invasive depth and lymph-vascular space invasion (LVSI), and these inverse relationships were significant (p=0.034, p=0.019, respectively). CD133 was more expressed by early stage tumor (FIGO I-II) compared with those having FIGO III to IV stage disease (p=0.021). The most notable conclusion of the present study is that CD44 and CD133 might participate in early-stage endometrial cancer carcinogenesis, and their overexpression may facilitate the early diagnosis of endometrial cancers. Analysis of our results supports the hypothesis that CD44 expression tends to decrease as the disease becomes invasive and progressive. So, we concluded that CD44 down-regulation might warn of a more aggressive course and may have a link with poorly prognosis carcinosarcomas. Further examination of the expression and function of CD44 and CD133 with a greater number of carcinosarcomas is warranted.

AKT, EGFR, C-ErbB-2, and C-kit expression in uterine carcinosarcoma

Uterine carcinosarcoma (UCS) accounts for approximately 15% of uterine cancer-associated deaths in the United States. With lack of effective treatment modalities, identification of underlying molecular defects may allow the introduction of targeted treatments. The expression of AKT, epithelial growth factor receptor, C-Kit, and C-ErbB-2 were studied by immunohistochemistry and exons 9 and 20 of PIK3CA gene were sequences in a cohort of 37 UCS, including 23 early-stage (I and II) and 14 late-stage (III and IV) tumors. Twenty-three (62%) of the UCS were homologous; the reminder contained heterologous elements. The carcinomatous component was pure serous carcinoma in 13 (35%), endometrioid in 12 (32%) cases. An immunostaining score ranging from 0 to (6+) was calculated for AKT, epithelial growth factor receptor, and C-Kit. C-ErbB-2 staining was scored by American Society of Clinical Oncology/College of American Pathologists criteria. AKT staining was seen in 35/37 cases with an immunostaining score ranging from (2+) to (5+). AKT was expressed significantly more in the early-stage than late-stage disease (P=0.016). The expression of AKT in the epithelial component was associated with the survival (P=0.026). Epithelial growth factor receptor was positive in 21/37 cases. Only 8 cases showed (≤3+) immunostaining score with C-Kit. C-ErbB-2 immunostain was (3+) in only 1 case. An H1047R mutation on PIK3CA gene was detected in both carcinomatous and sarcomatous components in a single case. These results indicate that AKT pathway may be important in pathogenesis of UCS. Further studies with larger cohorts are warranted to confirm the observed associations in this study.

Extravascular migratory metastasis in gynaecological carcinosarcoma

AIMS

Extravascular migratory metastasis (EVMM) is a potential mechanism of tumour spread reported most extensively in cutaneous melanoma. It has not been described previously in gynaecological malignancies. We describe EVMM in four gynaecological carcinosarcomas.

METHODS AND RESULTS

Extravascular migratory metastasis was observed in an ovarian carcinosarcoma during routine diagnostic assessment. Twenty-three additional, randomly selected gynaecological carcinosarcomas (11 tubo-ovarian and 12 endometrial) were examined retrospectively and EVMM was identified in three of these. Other than the index case, EVMM was a focal finding, identified in 12-18% of slides. The malignant cells demonstrating EVMM appeared sarcomatoid and were distributed abluminally, partly or completely surrounding the endothelium. Affected vessels often showed mural fibrin deposition. Immunohistochemistry for α-smooth muscle actin (SMA), CD31, CD34, D2-40, laminin and type IV collagen was performed on the EVMM-positive cases. The perivascular malignant cells showed more consistent SMA and laminin immunoreactivity than the non-vascular tumour elements.

CONCLUSIONS

Extravascular migratory metastasis is a hitherto unrecognized mechanism of tumour spread in gynaecological carcinosarcomas. The perivascular tumour cells appear to adopt a pericytic phenotype, and this may represent a specific pattern of epithelial-mesenchymal transition. Further studies with pericyte-specific immunohistological markers may better demonstrate the presence and possible prognostic significance of EVMM in gynaecological tumours.

A core microRNA signature associated with inducers of the epithelial-to-mesenchymal transition

Although it is becoming clear that certain miRNAs fulfil a fundamental role in the regulation of the epithelial-to-mesenchymal transition (EMT), a comprehensive study of the miRNAs associated with this process has yet to be performed. Here, we profiled the signature of miRNA expression in an in vitro model of EMT, ectopically expressing in MDCK cells one of seven EMT transcription factors (SNAI1, SNAI2, ZEB1, ZEB2, TWIST1, TWIST2 or E47) or the EMT inducer LOXL2. In this way, we identified a core subset of deregulated miRNAs that were further validated in vivo, studying endometrial carcinosarcoma (ECS), a tumour entity that represents an extreme example of phenotypic plasticity. Moreover, epigenetic silencing through DNA methylation of miRNA genes of the miR-200 family and miR-205 that are down-regulated during EMT was evident in both the in vitro (MDCK transfectants) and in vivo (ECS) models of EMT. The strong correlation between expression and DNA methylation suggests a major role for this epigenetic mark in the regulation of the miR-141-200c locus.

TGFβ-pathway is down-regulated in a uterine carcinosarcoma: a case study

Data assessing the role of various genetic alterations in uterine carcinosarcoma (CS), particularly the transforming growth factors-β (TGFβ) that play a crucial role in many cellular processes, including proliferation, differentiation, adhesion and migration, are scarce. TGFβ exert their effects through specific receptors and associated auxiliary receptors. In the current study, we investigated the expression of TGFβ isoforms and their receptors, as well as selected genes in a case of CS. We applied the real-time fluorescence detection PCR method with FAM dye-labeled TaqMan specific probes. In a comparison to the normal counterpart, TGFB1, TGFB2, TGFBRII, TGFBR3, ENG and CD109 were all down-regulated in uterine CS samples at different extents. BIRC5 and hTERT, markers of tumor survival, were up-regulated in CS as compared with normal counterparts. A concomitant increase of the hypoxia marker HIF1A expression pattern was noted, whereas the expression of GPR120, responsible for free fatty acids sensing, was not different in both counterparts evaluated. In conclusion, deregulation of various cellular mechanisms in uterine CS is associated with alterations at many levels - cell growth and proliferation, apoptosis, and impaired response to stimuli from extracellular environment.

Epithelial-mesenchymal transition in carcinomas of the female genital tract

Invasion is a defining feature of malignancy, but the mechanisms of invasion in many common cancers, including gynaecological malignancies, remain unclear. However, it has been proposed that malignant cells may usurp a normal embryological process, epithelial-mesenchymal transition (EMT), as a means of acquiring migratory capacity. The synergistic role of the tumour microenvironment in EMT induction has also been explored and helps to explain the spatially restricted distribution of EMT at the deep tumour margin (invasive front). Furthermore, tumour cells undergoing EMT may acquire cancer stem cell characteristics, and this may be relevant to the entire metastatic process and to tumour recurrence and treatment failure. Nevertheless, doubts persist regarding the role of EMT in malignant progression in vivo, partly because few studies have correlated molecular and histological alterations in clinical pathology specimens. In the current review we summarize the evidence for EMT in the common gynaecological epithelial malignancies, and discuss the morphological and immunohistochemical changes occurring at the invasive tumour front that may represent EMT-like processes. The possibility that carcinosarcomas represent a variant type of EMT with 'fixed' mesenchymal differentiation is also considered. Diagnostic histopathologists are ideally placed to critically evaluate the role of EMT in gynaecological and other types of malignancy.

Molecular events in endometrial carcinosarcomas and the role of high mobility group AT-hook 2 in endometrial carcinogenesis

The molecular events implicated in the development of endometrial carcinosarcoma remain poorly understood. Using complementary DNA microarrays, we analyzed a group of 15 endometrial carcinosarcomas and compared their gene expression profiles with those obtained from a group of 23 endometrioid endometrial carcinomas. We demonstrated changes in the expression of genes modulating processes such as the epithelial to mesenchymal transition, muscle differentiation, the expression of cancer/testis antigens, and immune response in endometrial carcinosarcomas. The high mobility group AT-hook 2 gene is an embryonic nuclear factor that mediates epithelial to mesenchymal transition in various tumor models, and it was among the genes overexpressed in endometrial carcinosarcomas. High mobility group AT-hook 2 overexpression was confirmed in 54% of endometrial carcinosarcomas by quantitative real time-polymerase chain reaction and immunohistochemistry. Moreover, we found a significant inverse correlation between the expression of high mobility group AT-hook 2 and let-7b, a member of the let-7 family of microRNAs that represses high mobility group AT-hook 2 expression. These changes were also associated with overexpression of Lin28B, a suppressor of microRNA biogenesis that is implicated in cancer progression and metastasis. Finally, high mobility group AT-hook 2 overexpression, which was detected in less than 3% of endometrioid endometrial carcinomas, was observed in many nonendometrioid carcinomas (46% of 28 samples). This pattern of expression, restricted to nonendometrioid carcinomas and endometrial carcinosarcomas, reflects a role for high mobility group AT-hook 2 in endometrial carcinogenesis that is associated with aggressive phenotypes and points to its potential use as a marker to distinguish between endometrioid and nonendometrioid tumors.

Endometrial carcinoma: molecular alterations involved in tumor development and progression

In the western world, endometrial carcinoma (EC) is the most common cancer of the female genital tract. The annual incidence has been estimated at 10-20 per 100,000 women. Two clinicopathological variants are recognized: the estrogen related (type I, endometrioid) and the non-estrogen related (type II, non-endometrioid).The clinicopathological differences are paralleled by specific genetic alterations, with type I showing microsatellite instability and mutations in phosphatase and tensin homologue deleted on chromosome 10, PIK3CA, K-RAS and CTNNB1 (β-catenin), and type II exhibiting TP53 mutations and chromosomal instability. Some non-endometrioid carcinomas probably arise from pre-existing endometrioid carcinomas as a result of tumor progression and, not surprisingly, some tumors exhibit combined or mixed features at the clinical, pathological and molecular levels. In EC, apoptosis resistance may have a role in tumor progression. Understanding pathogenesis at the molecular level is essential in identifying biomarkers for successful targeted therapies. In this review, the genetic changes of endometrial carcinogenesis are discussed in the light of the morphological features of the tumors and their precursors.

Endometrial carcinomas: a review emphasizing overlapping and distinctive morphological and immunohistochemical features

This review focuses on the most common diagnostic pitfalls and helpful morphologic and immunohistochemical markers in the differential diagnosis between the different subtypes of endometrial carcinomas, including: (1) endometrioid versus serous glandular carcinoma, (2) papillary endometrioid (not otherwise specified, villoglandular and nonvillous variants) versus serous carcinoma, (3) endometrioid carcinoma with spindle cells, hyalinization, and heterologous components versus malignant mixed müllerian tumor, (4) high-grade endometrioid versus serous carcinoma, (5) high-grade endometrioid carcinoma versus dedifferentiated or undifferentiated carcinoma, (6) endometrioid carcinoma with clear cells versus clear cell carcinoma, (7) clear cell versus serous carcinoma, (8) undifferentiated versus neuroendocrine carcinoma, (9) carcinoma of mixed cell types versus carcinoma with ambiguous features or variant morphology, (10) Lynch syndrome-related endometrial carcinomas, (11) high-grade or undifferentiated carcinoma versus nonepithelial uterine tumors. As carcinomas in the endometrium are not always primary, this review also discusses the differential diagnosis between endometrial carcinomas and other gynecological malignancies such as endocervical (glandular) and ovarian/peritoneal serous carcinoma, as well as with extra-gynecologic metastases (mainly breast and colon).

PPP2R1A mutations are common in the serous type of endometrial cancer

Recently unbiased sequencing efforts identified PPP2R1A mutations in clear cell ovarian cancers (OCC). Similar mutations were also noted with high frequency in uterine serous carcinoma. Because the endometrium develops from the same developmental precursors we further examined the hypothesis that PPP2R1A mutations might also occur in diverse histologic subtypes of uterine cancer. We sequenced the PPP2R1A in 22 cell line models of uterine cancer and 10 primary cancers. We found no mutations in the cell lines originally derived from endometrioid (n = 13), undifferentiated (n = 3), clear cell (n = 1), and carcinosarcoma (n = 3) cancers. However, we found a CCC (Pro) to CGC (Arg) codon 179 mutation in the ACI-158 serous carcinoma cell line, a CCC (Pro) to CTC (Leu) in a primary serous carcinoma as well as a CGC (Arg) to CAC (His) codon 258 mutation in a poorly differentiated endometrioid cancer. We sequenced a large panel of endometrial malignancies (n = 181) and found 12 mutants. Importantly, we confirmed a high frequency of mutation in 8 of 25 (32%) serous carcinomas a subtype with well-recognized poor prognosis. Mutations were infrequent in endometrioid cancer and absent in clear cell and carcinosarcoma subtypes. The PPP2R1A mutation regions are conserved among species and known to interact with the regulatory subunits of the PP2A enzyme. PPP2R1A mutant endometrial cancers may represent good candidates for personalized drug therapies particularly for women with the lethal serous histologic variant of uterine cancer.