Variable Expression of MSH6 in Endometrial Carcinomas With Intact Mismatch Repair and With MLH1 Loss Due to MLH1 Methylation

Immunohistochemistry for mismatch repair proteins MLH1, MSH2, MSH6, and PMS2 is an effective screen to detect individuals at risk for Lynch syndrome. College of American Pathologists guidelines stipulate that protein expression should be reported as present versus absent, as most patients with germline mutations in a mismatch repair gene have complete loss of protein expression in tumor cells. A similar approach is employed to screen for cancer patients eligible for immune checkpoint blockade. This “all or none” interpretive approach ignores substantial evidence that mismatch repair may be more finely regulated by other mechanisms. We have observed clinically that MSH6 expression is variable, even in carcinomas that are overall considered positive for MSH6 expression. A proof-of-principle study was therefore designed to more rigorously quantify the protein expression of MSH6 and its binding partner, MSH2, using image analysis applied to age-matched endometrioid grade 2 subsets that were either mismatch repair intact or MLH1-deficient due to MLH1 gene methylation. In both endometrioid groups, MSH6 expression was significantly lower than MSH2 expression. MSH6 expression increased in higher grade, mismatch repair intact serous carcinomas, but it was still significantly lower than that for MSH2. MSH2 expression was consistently high across the 3 different tumor groups. These results suggest that MSH6 expression is subject to wide fluctuations in expression, even when ...
Source: International Journal of Gynecological Pathology - Category: Pathology Tags: PATHOLOGY OF THE CORPUS: ORIGINAL ARTICLES Source Type: research

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Lynch syndrome (LS) is an autosomal dominant disease caused by a germline mutation in DNA mismatch repair genes which increases the risk of several cancers such as endometrial and colorectal cancers. However, there are only a few reports of peritoneal malignancies in patients with LS. Herein, we report the first case of a primary peritoneal low-grade serous carcinoma in a woman with LS and provide a literature review of peritoneal malignancies in patients with LS. The patient was a 72-yr-old gravid 2 para 2 Japanese woman with a germline mutation in MLH1. She had a history of colon cancer and endometrial cancer and was tre...
Source: International Journal of Gynecological Pathology - Category: Pathology Tags: PATHOLOGY OF THE UPPER TRACT: CASE REPORTS Source Type: research
Endometrial carcinoma (EC), as described by Bokhman, has historically been classified as Type I (low-grade, hormone-dependant, young patients, good prognosis) or Type II (high-grade, hormone-independent, older patients, poor prognosis). This classification is no longer pragmatic, however, as EC is a much more heterogeneous disease. Four molecular subtypes of EC were identified by The Cancer Genome Atlas (TCGA), and subsequent studies have demonstrated its utility in predicting prognosis. While endometrial serous carcinoma (ESC), the prototypical Type II EC, largely occurs in older women, younger women with ESC were not acc...
Source: The American Journal of Surgical Pathology - Category: Pathology Tags: Original Articles Source Type: research
Mismatch repair deficiency (MMRD) is involved in the initiation of both hereditary and sporadic tumors. MMRD has been extensively studied in colorectal cancer and endometrial cancer, but not so in other tumors, such as ovarian carcinoma. We have determined the expression of mismatch repair proteins in a large cohort of 502 early-stage epithelial ovarian carcinoma entailing all the 5 main subtypes: high-grade serous carcinoma, endometrioid ovarian carcinoma (EOC), clear cell carcinoma (CCC), mucinous carcinoma, and low-grade serous carcinoma. We studied the association of MMRD with clinicopathologic and immunohistochemical ...
Source: The American Journal of Surgical Pathology - Category: Pathology Tags: Original Articles Source Type: research
Abstract About 23% of adnexal tumors are related to a hereditary syndrome, most often hereditary breast and ovarian cancer syndrome or Lynch syndrome, responsible of epithelial tumors. However, the pathologist should be aware of rare hereditary syndromes responsible of non-epithelial ovarian tumors. Ovarian tumors associated with germline mutation of BRCA genes are essentially high-grade serous carcinomas of tubal origin, while those seen in Lynch syndrome are most often endometrioid or clear cell carcinomas. Sex-cord tumors associated with a familial predisposition are Sertoli-Leydig cell tumors in DICER syndrome...
Source: Annales de Pathologie - Category: Pathology Authors: Tags: Ann Pathol Source Type: research
This review is an appraisal of the current state of knowledge of 2 enigmatic histotypes of ovarian carcinoma: endometrioid and clear cell carcinoma. Both show an association endometriosis and the hereditary nonpolyposis colorectal cancer (Lynch) syndrome, and both typically present at an early stage. Pathologic and immunohistochemical features that distinguish these tumors from high-grade serous carcinomas, each other, and other potential mimics are discussed, as are staging, grading, and molecular pathogenesis.
Source: Surgical Pathology Clinics - Category: Pathology Authors: Source Type: research
CONCLUSION: Ovarian cancer in women with LS has a wide age-range of onset, is usually diagnosed at an early stage with predominantly endometrioid type histology and a good overall survival. The early stage at diagnosis could not be attributed to annual gynecological surveillance. PMID: 29880284 [PubMed - as supplied by publisher]
Source: Gynecologic Oncology - Category: Cancer & Oncology Authors: Tags: Gynecol Oncol Source Type: research
Microcystic, elongated, and fragmented (MELF) pattern invasion is a poor prognostic indicator in uterine endometrioid carcinoma, but its existence, biology, and prognostic value have not been described in ovarian endometrioid carcinoma. We evaluated cases of ovarian endometrioid carcinoma without synchronous uterine endometrioid carcinoma for MELF and other histologic features. To evaluate tumor biology, we assessed an immunohistochemical profile, including MLH1, PMS2, MSH2, MSH6, β-catenin, e-cadherin, CK19, and cyclin D1. A retrospective chart review evaluated clinical and demographic features and survival. The Fish...
Source: International Journal of Gynecological Pathology - Category: Pathology Tags: Pathology of the Upper Genital Tract: Original Articles Source Type: research
Hereditary breast and ovarian cancer (HBOC) syndrome and Lynch syndrome (LS) are associated with increased risk of developing ovarian carcinoma. Patients with HBOC have a lifetime risk of up to 50% of developing high-grade serous carcinoma of tube or ovary; patients with LS have a 10% lifetime risk of developing endometrioid or clear cell carcinoma of the ovary. Testing all patients with tubo-ovarian high-grade serous carcinoma for mutations associated with HBOC syndrome, and all patients presenting with endometrioid or clear cell carcinoma of the ovary for mutations associated with LS can identify patients with undiagnose...
Source: Surgical Pathology Clinics - Category: Pathology Authors: Source Type: research
ConclusionOur data support the motion for a histotype‐specific Lynch syndrome screening in ovarian carcinoma confined to endometrioid and clear cell carcinomas.This article is protected by copyright. All rights reserved.
Source: Histopathology - Category: Pathology Authors: Tags: Original Article Source Type: research
Epithelial ovarian cancer is a heterogeneous group of cancers, and molecular tools are urgently needed for a better understanding and targeted management of this often lethal disease. Since epigenetic methods can offer new tools for the management of ovarian cancer, our aim was to investigate epigenetic mechanisms in ovarian tumorigenesis representing different histological types. Expression profiling of ovarian and endometrial cancer cell lines treated with demethylating agents as well as literature were used to select gene candidates for epigenetic regulation. A methylation-specific multiplex ligation-dependent probe amp...
Source: Cancer Research - Category: Cancer & Oncology Authors: Tags: Molecular and Cellular Biology Source Type: research
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