Mismatch Repair Deficiency in Uterine Carcinosarcoma: A Multi-institution Retrospective Review

Molecular Classification Outperforms Histologic Classification in Prognostication of High-grade Endometrial Carcinomas With Undifferentiated and Sarcomatous Components

Since the establishment of 4 molecular subgroups of endometrial carcinoma (EC), there has been significant interest in understanding molecular classification in the context of histologic features and diagnoses. ECs with undifferentiated, spindle, and/or sarcomatous components represent a diagnostically challenging subset of tumors with overlapping clinical and histologic features. We examined the clinicopathologic, morphologic, immunohistochemical, and molecular features of these tumors identified in our institutions' pathology databases using immunohistochemistry and targeted sequencing. Disease-specific survival (DSS) and progression-free survival (PFS) were analyzed using Kaplan-Meier curves and log-rank tests. One hundred sixty-two ECs were included: carcinosarcomas (UCS; n=96), dedifferentiated/undifferentiated EC (DDEC/UDEC; n=49), and grade 3 endometrioid EC with spindled growth (GR3spEEC) (n=17). All molecular subgroups were represented in all histologic subtypes and included 12 (7%) POLE -mutated ( POLE mut), 43 (27%) mismatch repair-deficient (MMRd), 77 (48%) p53-abnormal (p53abn), and 30 (19%) no specific molecular profile (NSMP) tumors. However, the molecular classification (irrespective of histologic diagnosis) was a significant predictor for both DSS ( P =0.008) and P≤0.0001). POLE mut EC showed an excellent prognosis with no recurrences or deaths from the disease. MMRd tumors also showed better outcomes relative to NSMP and p53abn tumors. In conclusion, molecular classification provides better prognostic information than histologic diagnosis for high-grade EC with undifferentiated and sarcomatous components. Our study strongly supports routine molecular classification of these tumors, with emphasis on molecular group, rather than histologic subtyping, in providing prognostication.

Comparative analysis of PD-L1 expression and tumor-infiltrating lymphocytes in metaplastic breast carcinoma and gynecologic carcinosarcoma: A single-institution retrospective study

Metaplastic breast carcinoma (MBC) and gynecologic carcinosarcoma (GCS) are rare, clinically aggressive cancers that demonstrate epithelial components and mesenchymal or sarcomatoid components. In this study, we assessed PD-L1 expression and tumor-infiltrating lymphocytes (TILs) in MBC and GCS. Overall, PD-L1 positivity using the SP142 clone was seen in 50 % of MBC and 51.9 % of GCS cases, with PD-L1 expression in tumor cells significantly higher in MBC cases (p = 0.034), and PD-L1 expression in immune cells similar in MBC and GCS cases. PD-L1 expression was significantly higher in epithelial components than in mesenchymal components in both MBC and GCS cases (p = 0.0005). TILs were low in the majority of MBC and GCS cases (≥ 10 %) and generally correlated with PD-L1 expression; however, many PD-L1 positive cases with low TILs were seen. PD-L1 expression using the 22C3 clone was additionally assessed, with positivity seen in 62.9 % of MBC cases and 30 % of GCS cases. Concordance between SP142 and 22C3 results was seen in 62.5 % of MBC cases and 80 % of GCS cases. Overall, our findings suggest that a subset of MBC and GCS cases may benefit from immune checkpoint inhibitor therapy. Our findings also illustrate unique aspects of PD-L1 expression patterns in these tumors which may harbor additional prognostic and therapeutic significance.

POLE-mutated Endometrial "Carcinosarcoma"

The molecular subtype classification of endometrial carcinomas has conceptually changed our approach to this disease. However, open questions remain about how to integrate certain histotype diagnoses with the molecular subtype. We report 2 cases with morphologic suspicion for endometrial carcinosarcoma, that still fell short of the essential criteria for diagnosing carcinosarcoma. On subsequent molecular testing pathogenic POLE mutations were detected and a descriptive diagnosis of endometrial endometrioid carcinomas, low-grade with a homologous sarcoma component was rendered. This challenges the existence of POLE-mutated "carcinosarcoma."

Dedifferentiated endometrial carcinoma arising from serous carcinoma: Diagnostic challenges and recommendations

•Dedifferentiated endometrial carcinoma arising from serous carcinoma (null-type P53).•Differential diagnosis including carcinosarcoma, FIGO grade 3 endometrioid carcinoma.•Also need to rule out SMARCA4-deficient uterine sarcoma and other sarcomas.

The expression of programmed death-ligand 1 and programmed death-ligand 2 in endometrial carcinosarcoma: Correlation with mismatch repair protein expression status, tumor-infiltrating lymphocyte infiltration, and clinical outcomes

BACKGROUND

Endometrial carcinosarcomas have high malignant potential with a high recurrence rate and poor prognosis. Immunotherapy may be a promising treatment option. The aim of this study is to evaluate the expression of PD-L1/PD-L2 and its relationship to mismatch repair (MMR) protein status and tumor-infiltrating lymphocyte (TIL) density.

METHODS

We performed immunohistochemical analyses of PD-L1 (clone 22C3), PD-L2 (clone TY25), MSH-2, MSH-6, PMS-2, and MLH-1 in 77 tumors. We count TILs using CD8 antibody. Clinicopathologic features were recorded and statistically correlated with immunohistochemical results. Kaplan-Meier analyses were used to analyze the prognosis.

RESULTS

While PD-L1 positivity was seen more commonly in MMR protein deficient tumors (p = 0.010), PD-L2 positivity was seen more commonly in MMR protein proficient tumors (p = 0.003). PD-L1 positivity was also found to be more common in carcinosarcoma with high TIL infiltration. PD-L2 positivity was associated with decreased overall survival (OS) rates (p = 0.043, p = 0.043, respectively), whereas the PD-L1 positivity and TIL density were not significantly associated with OS rate. The OS rate of patients with MMR protein proficient tumors was significantly lower compared with those with MMR protein deficient tumors (p = 0.042). The lower TILs infiltration was associated with a shorter disease-free survival (DFS) rate. PD-L1 and PD-L2 positivity did not affect the DFS rate.

CONCLUSIONS

PD-L1/PD-L2 might be a better target for immunotherapy in endometrial carcinosarcoma. PD-L2 positivity was also associated with a worse clinical outcome in patients with endometrial carcinosarcoma, suggesting that PD-L2 status can be used to predict clinical behavior. Further studies are needed to elucidate the relationship between PD-L1/PD-L2 expression and therapeutic response.

Uterine carcinosarcoma with intestinal involvement: A case report and literature review

Uterine carcinosarcoma (UCS) is a high-grade endometrial cancer characterized by two components: Carcinomatous (epithelial) and sarcomatous (stromal tissue) elements. The present study describes a clinical case of this type of UCS and also provides a brief literature review of this type of tumor. A 72-year-old female visited the emergency department of the authors' hospital with pain in the hypogastric region, intestinal dysrhythmia since 3 months prior, fever and a palpable abdominal mass. Laboratory test results revealed sepsis and mild anemia and an imaging test revealed a large uterine tumor with wide areas of necrosis and adenopathies. As determined by the multidisciplinary committee, surgery was considered the main treatment option and this was performed with no incidences. Carcinosarcoma is a rare tumor, which most frequently occurs in older women. The diagnosis is based on symptoms and imaging tests, such as ecography and scans. The gold standard of treatment is surgery, although it is possible that other types of therapies, such as chemotherapy and radiotherapy may also be effective, depending on the tumor stage. On the whole, the prognosis of patients with this type of tumor is poor, with a low survival rate, even in earlier stages due to its malignant component and the possibility for metastasis. Surgery is the optimal treatment for this type of tumor, if this is possible, always individualizing patients.

Management and Prognosis of Patients with Recurrent or Persistent/Progressive Uterine Carcinosarcoma

Uterine carcinosarcoma (UCS) is a highly aggressive gynecologic malignancy. Recurrent or persistent/progressive disease is usually fatal. We aimed to investigate the management and prognosis of these patients. Clinical records of UCS patients from June 1987 to April 2020 were retrospectively reviewed. The stage was re-assigned with the FIGO 2009 staging system. Univariate and multivariate analyses were used to identify the independent predictors of survival after recurrence (SAR) and cancer-specific survival (CSS). Of the 168 patients, 98 experienced treatment failure. The median time to treatment failure (TTF) was 8.1 months (range: 0.0-89.1). The median follow-up time of censored patients was 32.0 months (range: 16.8-170.7). The 5-year SAR rates of those with recurrent or persistent/progressive disease were 7.6%. On multivariate analysis, salvage therapy mainly using radiotherapy (HR 0.27, 95% CI: 0.10-0.71) or chemotherapy (HR 0.41, 95% CI: 0.24-0.72) or chemoradiotherapy (CRT) (HR 0.33, 95% CI: 0.15-0.75) were associated with improved SAR, whereas disseminated recurrence was associated with significantly worse SAR (HR 3.94, 95% CI: 1.67-9.31, p = 0.002). Salvage therapy using radiotherapy or chemotherapy or CRT significantly improved SAR. Surgery significantly improved CSS but not SAR, adjusting for confounding factors.

Microsatellite instability and oncological outcomes in Thai patients with endometrial cancer

Here, we determined the frequency of microsatellite instability (MSI) and the impact of MSI-high (MSI-H) on clinical outcomes of Thai patients with endometrial cancer (EC). Tissue samples of 110 Thai patients with EC, who had undergone surgical staging, were tested for mismatch repair (MMR) gene deficiency, and the patients were grouped into MSI-H and MSI-stable (MSI-S) groups; 24.5% had MSI-H. Unlike MSI-S group patients, MSI-H group patients had synchronous and metachronous cancer. They showed better 3-year disease-free survival (DFS) than those in the MSI-S group (p=.182; 92.3% vs. 82.6%). The 3-year overall survival was 96.2% in MSI-H and 86.4% in MSI-S groups (p=.163). Multivariate analyses showed lower uterine involvement (p=.004), myometrial invasion ≥50% (p=.032), lymphovascular space invasion (p<.001) and MSI-S (p=.006) as prognostic factors for DFS. Our study showed that the prevalence of MMR gene deficiency in Thai patients with EC is common and associated with better outcomes.Impact StatementWhat is already known on this subject? Microsatellite instability (MSI) occurs in approximately 20-40% of endometrial cancer (EC) cases. MSI analysis in EC can identify patients at higher risk of hereditary nonpolyposis colorectal cancer and those having prognostic factors. Additionally, it is predictive of immune checkpoint inhibitor treatment. However, current evidence shows a correlation between clinicopathological characteristics and EC prognosis. Studies on EC and MSI status effect on survival outcome have yielded inconsistent results regarding the pathological significance of MSI in such malignancies.What do the results of this study add? The prevalence of mismatch repair (MMR) gene deficiency in Thai patients with EC is common (24.5%) and associated with better outcomes.What are the implications of these findings for clinical practice and/or further research? This study highlights the prevalence and impact of MSI on oncological outcomes in patients with EC in a low-incidence country. Future studies should focus on the detection of germline mutation to understand the accurate prevalence of Lynch syndrome in Thai patients with EC.

Uncommon and Difficult High-Grade Endometrial Carcinomas

This article presents features of uncommon high-grade endometrial carcinomas that often pose a significant diagnostic challenge. An update on undifferentiated and dedifferentiated endometrial carcinoma is first provided, followed by discussions on more recently defined entities such as mesonephric-like carcinoma of the endometrium and gastric-type endometrial carcinomas. Finally, endometrial carcinoma with germ cell or trophoblastic-like components is discussed.

HER2 Overexpression and Amplification in Uterine Carcinosarcomas With Serous Morphology

Uterine carcinosarcoma (UCS) is an aggressive malignancy with few treatment options. A recent clinical trial has shown an increase in progression-free survival in patients with human epidermal growth factor receptor 2 (HER2)-positive serous endometrial carcinomas treated with anti-HER2-targeted therapies. Few studies have evaluated HER2 expression/amplification in UCS. Similar to serous endometrial carcinoma, the majority of UCS have TP53 mutations and a serous epithelial component, suggesting that UCS may show similar rates of HER2 positivity and therapeutic response. Therefore, we evaluated HER2 expression/amplification in a cohort of UCS over a 5-year period. HER2 immunohistochemistry (IHC) and chromogenic in situ hybridization were performed on tissue microarray and whole tissue sections and scored according to the most recent clinical trial recommendations. Three of 48 UCS (6%) had strong (3+) HER2 IHC expression, and 3 cases (6%) were equivocal (2+). Seven cases (15%) had HER2 amplification by chromogenic in situ hybridization, including all 3 with overexpression and 2 that were equivocal by IHC. Mismatch repair (MMR) protein, p53, and programmed cell death-ligand 1 (PD-L1) expression status was obtained from prior whole section analyses. All HER2-positive cases had a serous morphology and aberrant p53 expression. Only minimal PD-L1 expression was seen in the HER2-positive cases, and none had MMR loss. A subset of UCS with serous morphology have overexpression and/or amplification of HER2, which may predict response to HER2-targeted therapies. HER2-positive UCS may be less susceptible to immune checkpoint inhibition as they uncommonly show MMR deficiency and/or strong PD-L1 expression. Thus, HER2-targeted therapies could be of clinical utility in a subset of UCS without other adjuvant treatment options.

Clinicopathological Features Associated with Microsatellite Instability/Mismatch Repair Deficiency in Uterine Carcinosarcoma: A Quantitative Systematic Review

INTRODUCTION

Recent studies suggested that microsatellite instability/mismatch repair deficiency (MSI/MMR-d) might define a clinicopathologically distinct subset of uterine carcinosarcomas (UCSs).

OBJECTIVE

The aim of this study was to compare clinicopathological features between MSI/MMR-d and microsatellite-stable/mismatch repair-proficient (MSS/MMR-p) UCSs.

METHODS

A quantitative systematic review was performed by searching electronic databases from January 2000 to January 2021. All studies assessing MSI/MMR status in UCS were included. Odds ratio (OR) with a significant two-tailed p value <0.05 was used to assess the association of MSI/MMR-d with clinicopathological features.

RESULTS

Eleven studies with 783 patients were included. MSI/MMR-d was directly associated with endometrioid (pure: p < 0.001; pure + mixed: p < 0.001), undifferentiated/dedifferentiated (p < 0.001), and clear cell carcinoma component (p = 0.046), and inversely associated with age >60 (p = 0.034), serous carcinoma component (pure: p < 0.001; pure + mixed: p < 0.001), heterologous sarcoma component (p = 0.027), TP53-mutation/p53-abnormal expression (p < 0.001), and recurrence (p < 0.001). MSI/MMR-d showed no significant association with advanced FIGO stage (OR = 1.259; p = 0.517), low-grade carcinoma component (pure: p = 0.596; pure + mixed: p = 0.307), mixed carcinoma component (p = 1), and proportion of patients "dead of disease" (p = 0.352), "alive with disease" (p = 1) or with "no evidence of disease" (p = 0.458).

CONCLUSION

MSI/MMR-d UCSs show younger age, more common endometrioid, undifferentiated or clear cell carcinoma component, and less common serous carcinoma component, heterologous sarcoma component, and TP53 mutation than MSS/MMR-p UCSs. Given the discrepancy between recurrence rate and oncologic outcomes at the last follow-up, further studies are necessary to define whether MSI/MMR-d UCSs have better prognosis.

Molecular Evaluation of Endometrial Dedifferentiated Carcinoma, Endometrioid Carcinoma, Carcinosarcoma, and Serous Carcinoma Using a Custom-Made Small Cancer Panel

It is often difficult to histologically differentiate among endometrial dedifferentiated carcinoma (DC), endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma (CS) due to the presence of solid components. In this study, we aimed to categorize these carcinomas according to The Cancer Genome Atlas (TCGA) classification using a small custom-made cancer genome panel (56 genes and 17 microsatellite regions) for integrated molecular diagnosis. A total of 36 endometrial cancer cases with solid components were assessed using IHC, next-generation sequencing (NGS), and the custom-made panel. Among 19 EC cases, six were categorized as MMR-deficient (MMR-d) and eight were classified as having a nonspecific molecular profile. Three EC cases were classified as POLE mutation (POLEmut)-type, which had a very high tumor mutation burden (TMB) and low microsatellite instability (MSI). Increased TMB and MSI were observed in all three DC cases, classified as MMR-d with mutations in MLH1 and POLD1. Except for one case classified as MMR-d, all SC cases exhibited TP53 mutations and were classified as p53 mutation-type. SC cases also exhibited amplification of CCND1, CCNE1, and MYC. CS cases were classified as three TCGA types other than the POLEmut-type. The IHC results for p53 and ARID1A were almost consistent with their mutation status. NGS analysis using a small panel enables categorization of endometrial cancers with solid proliferation according to TCGA classification. As TCGA molecular classification does not consider histological findings, an integrated analytical procedure including IHC and NGS may be a practical diagnostic tool for endometrial cancers.

PD-L1 and Mismatch Repair Status in Uterine Carcinosarcomas

Uterine carcinosarcomas have few adjuvant treatment options. Programmed cell death ligand-1 (PD-L1) expression in these tumors may predict response to checkpoint inhibitor therapies. An increase in PD-L1 expression has been shown in endometrial carcinomas with mismatch repair (MMR) deficiencies; however, few studies have evaluated PD-L1 expression in uterine carcinosarcomas. We examined PD-L1 expression in 41 cases of uterine carcinosarcoma using combined positive scores (CPS) and tumor proportion scores (TPS), and correlated with MMR status, p53 expression, and epithelial histotype. In addition to confirming the diagnosis of carcinosarcoma, the epithelial components were stratified based on endometrioid versus serous histology. Thirty-three cases (80%) were positive for PD-L1, defined as a CPS score of ≥1 or a TPS score of ≥1%. Twelve cases (29%) showed high expression of PD-L1, defined as a CPS score of ≥10 or a TPS score of ≥10%. The majority of the morphologically adjudicated carcinosarcomas had a serous epithelial component (83%) rather than endometrioid (17%), which was reinforced by aberrant p53 staining predominantly within cases with serous morphology. The majority of carcinosarcomas showed at least focal PD-L1 expression, predominantly in tumor-associated immune cells. Carcinosarcomas with endometrioid morphology were significantly more likely to have high-level PD-L1 (5/7 vs. 7/34; P=0.015). MMR-deficient carcinosarcomas were also more likely to have high-level PD-L1 (2/3 vs. 10/28); however, this did not reach statistical significance (P=0.2) and overall MMR-deficiency was uncommon (3 cases, 7%). These findings suggest that PD-L1 may be additive to MMR testing as a predictive biomarker for checkpoint inhibitor vulnerability in carcinosarcomas.

Corded and Hyalinized and Spindled Endometrioid Endometrial Carcinoma: A Clinicopathologic and Molecular Analysis of 9 Tumors Based on the TCGA Classifier

Corded and hyalinized and spindled carcinomas are rare variants of endometrioid carcinoma (EC) characterized by cords of low-grade epithelial cells (±spindle cells) within a hyalinized stroma or spindled epithelial cells, respectively, that merge with conventional low-grade EC. Due to their "biphasic" morphology, these tumors are often misdiagnosed as carcinosarcoma. The clinicopathologic features including mismatch repair protein (PMS2 and MSH6) and p53 immunohistochemical expression and POLE mutational status of 9 corded and hyalinized and spindled endometrial ECs were evaluated and classified into The Cancer Genome Atlas (TCGA) based molecular subgroups. Beta-catenin immunohistochemistry was performed as a surrogate for CTNNB1 mutational status. The mean age at diagnosis was 49 years (range: 34 to 68 y) with staging information available for 6 patients: stage IA (n=1), stage IB (n=1), stage II (n=2), stage IIIA (n=1), stage IIIC1 (n=1). A prominent corded and hyalinized component was present in 7 ECs comprising 15% to 80% of the tumor with a minor (5% to 15%) spindled morphology in 5. Two additional tumors were composed of a low-grade spindled component comprising 25% to 30% of the neoplasm. Tumors were grade 1 (n=3), grade 2 (n=5), and grade 2 to 3 (n=1) and squamous differentiation was identified in 8/9. All tumors had preserved expression of mismatch repair proteins with 8 showing a p53 wild-type phenotype including the grade 2 to 3 EC; 1 grade 2, stage IB tumor exhibited a mutant pattern of expression. All (n=7) but 1 tumor demonstrated nuclear beta-catenin expression in the glandular, squamous, and corded or spindled components. POLE exonuclease domain mutations were absent in all tumors. Based on our findings, corded and hyalinized EC and EC with spindle cells are usually low grade, low stage, and present at a younger age and exhibit squamous differentiation at an increased frequency compared to typical EC. Unlike carcinosarcomas, which frequently harbor TP53 mutations, these tumors usually exhibit wild-type p53 and nuclear beta-catenin expression, indicative of underlying CTNNB1 mutations. According to the TCGA subgroups of endometrial carcinoma, the majority of corded and hyalinized and spindled EC appear to fall into the copy number low ("no specific molecular profile") subgroup.

Mixed Endometrioid Adenocarcinoma and Müllerian Adenosarcoma of the Uterus and Ovary: Clinicopathologic Characterization With Emphasis on its Distinction From Carcinosarcoma

Mullerian adenosarcoma is a biphasic neoplasm composed of benign or atypical Müllerian epithelium and a malignant mesenchymal component that is usually, but not always, of low grade. Focal architectural or cytologic atypia of the epithelial component resembling atypical hyperplasia may uncommonly be present and foci of adenocarcinoma have been rarely reported. Whether the coexistence of these 2 tumor components is a result of independent primaries (collision tumor), adenocarcinoma arising from the epithelial component of the adenosarcoma, an unusual form of carcinosarcoma or some other mechanism is uncertain. To establish the diagnostic criteria and clinical significance of the coexistence of adenocarcinoma in close association with Müllerian adenosarcoma, we conducted a multi-institutional study of these rare tumors. Twenty-six patients were identified with "mixed" adenosarcoma and adenocarcinoma; they ranged in age from 43 to 87 years (median: 66 y). Tumors occurred in the uterine corpus (n=22), ovary (n=2), and the pelvis (n=2). All but 6 had International Federation of Gynecology and Obstetrics (FIGO) stage I disease. All extrauterine tumors were associated with endometriosis. The tumor size ranged from 2 to 25 cm (median: 7.9 cm). The sarcomatous component was of low grade in 18 and high grade in 8 (the majority demonstrating rhabdomyoblastic differentiation); 9 had stromal overgrowth. Twenty-five carcinomas were endometrioid in type (23 FIGO grade 1; 3 FIGO grade 2) and 1 carcinoma was dedifferentiated with FIGO grade 1 endometrioid adenocarcinoma component; 33% of the uterine neoplasms were associated with adjacent endometrial hyperplasia. Next-generation sequencing in 2 tumors identified similar molecular abnormalities in the sarcomatous and carcinomatous components supporting a clonal relationship. Of 10 patients with available follow-up (median: 18 mo), 8 had no evidence of disease and 2 died of recurrent sarcoma at 7 and 8 months. Endometrioid adenocarcinomas that arise in close spatial association with Müllerian adenosarcoma appear to be clonally related to the sarcoma. Unlike carcinosarcomas, these tumors are usually early stage at presentation. The prognosis appears to be driven by the sarcomatous component. These tumors should be distinguished from carcinosarcomas, dedifferentiated endometrial carcinomas, and corded and hyalinized endometrioid carcinomas.

Undifferentiated and dedifferentiated neoplasms of the female genital tract

Undifferentiated neoplasms in the female gynecologic tract comprise two main groups-undifferentiated carcinoma, most common in the endometrium and ovary, and undifferentiated uterine sarcoma, although tumors with an undifferentiated appearance may occur in all gynecologic organs. Their differential diagnosis is broad and generous sampling, careful morphological evaluation, judicious use of immunohistochemistry, and in many cases, molecular testing is often essential in the diagnostic work-up. As some of these neoplasms fail to respond to conventional chemotherapy regimens and/or radiation therapy, targeted therapy may be valuable in treating these highly aggressive tumors, thus the importance of precise diagnosis. In this review we discuss the clinicopathological features of undifferentiated carcinoma, dedifferentiated carcinoma, and undifferentiated uterine sarcoma, followed by a comprehensive analysis of morphological mimickers. Finally, we briefly review ovarian and lower genital tract tumors with an undifferentiated histological appearance.

DNA Mismatch Repair-deficient Endometrial Carcinosarcomas Portend Distinct Clinical, Morphologic, and Molecular Features Compared With Traditional Carcinosarcomas

Uterine carcinosarcomas (UCSs) are aggressive neoplasms composed of high-grade malignant epithelial and mesenchymal elements with most (∼90%) showing TP53 abnormalities. A subset, however, shows mismatch repair deficiency (MMR-D). We sought to describe their clinical, morphologic, and molecular features. Clinicopathologic data of MMR-D UCSs were recorded including age, stage, follow-up, mismatch repair and p53 immunohistochemistry (IHC), MLH1 promoter methylation status, and germline alterations, TP53 mutation status, microsatellite instability and mutational burden by massively parallel sequencing. Seventeen (6.2%) MMR-D were identified among 276 UCSs. Of MMR-D UCSs, the median age was 60 years. mismatch repair IHC loss is as follows: MLH1/PMS2 65%, MSH2/MSH6 18%, MSH6 12%, and PMS2 6%. MLH1 promoter methylation and Lynch syndrome was identified in 47% and 12% of cases, respectively. Cases with p53 IHC showed the following patterns: wild-type 70%, aberrant 20%, and equivocal 10%. Of cases with sequencing, 88% were hypermutated and microsatellite instability high. High-grade endometrioid, undifferentiated, and clear cell carcinoma was present in 53%, 41%, and 6% of cases, respectively and 47% also showed a low-grade endometrioid component. Most patients presented at an early stage (67%) and upon follow-up, 18% died of disease, 65% showed no evidence of disease, while 18% are alive with disease. Patients with MMR-D UCS are younger than the reported median age (70 y) for traditional UCS and most do not show p53 abnormalities. Low-grade endometrioid and undifferentiated carcinoma were seen in approximately half of all cases. Although UCSs have a high tendency for early extrauterine spread, most patients in our cohort presented at an early stage and at follow-up were no evidence of disease. MMR-D UCSs display distinct clinical, morphologic, and molecular features compared with traditional UCSs.

Dedifferentiated and undifferentiated neoplasms: A conceptual approach

This review provides a conceptual approach to dedifferentiation across a variety of tumor types, with particular attention to genetic events that tie together morphologically disparate areas of these neoplasms. First, working definitions of the terms differentiated, undifferentiated, and dedifferentiated are developed. Then, specific examples of tumors with a particular propensity for undergoing dedifferentiation are highlighted, with emphasis on both immunohistochemical studies and molecular lesions that enable surgical pathologists to establish diagnostic clarity in morphologically vexing situations. Throughout this review, the historical arc of the literature is followed, and therefore the discussion of specific tumor types begins with dedifferentiated chondrosarcoma, the neoplasm that inspired the terminology regarding dedifferentiation that remains in use today. Selected other sarcomas with well-established pathways of dedifferentiation are subsequently discussed, followed by descriptions of this process in subtypes of carcinoma and melanoma.

Immunohistochemical evaluation of mismatch repair proteins and p53 expression in extrauterine carcinosarcoma/sarcomatoid carcinoma

Introduction

Carcinosarcoma (CS) is a tumor with components: epithelial (carcinomatous) and mesenchymal (sarcomatous), developing in the mechanism of epithelial-mesenchymal transition. It is known that the p53 defect is a frequent finding in a carcinosarcoma in different anatomical locations, additionally, in a subgroup of uterine CS MMR defect plays a role in the pathogenesis. The aim of this paper was to investigate the frequency of MMR and p53 aberrations in extrauterine CS.

Material and methods

Twenty eight extrauterine CS from the lung (n = 8), breast (n = 6), head and neck (n = 5), ovary (n = 3), urinary bladder (n = 3), adrenal gland (n = 1), skin (n = 1), and stomach (n = 1) were stained for hMLH1, PMS2, hMSH2, hMSH6 and p53. The pattern of expression was evaluated separately in carcinomatous and sarcomatous component.

Results

Immunostainings for hMLH1, PMS2, hMSH2 and hMSH6 were positive in all tumors. p53 defect was observed in 19 out of 28 samples (67.85%). In all cases except one (96.42%) there was a concordance between sarcomatoid and carcinomatous components.

Conclusions

MMR deficiency does not seem to play a role in the pathogenesis of extrauterine CS. p53 aberrant expression is frequent and almost always consistent in carcinomatous and sarcomatous component.