Unusual DNA mismatch repair-deficient tumors in Lynch syndrome: a report of new cases and review of the literature

A novel lynch syndrome kindred with hereditary adrenal cortical carcinoma

BACKGROUND

Adrenal cortical carcinoma (ACC) is an extremely rare malignancy, and advanced ACC carries a very poor prognosis. Early detection is critical since early-stage disease can be cured with surgical resection. ACC can be seen in Lynch syndrome; this case and review of the literature provide insight as to the potential biological origin of this malignancy. Clinicians should be aware of this association and the potential impact on cancer screening in these kindreds.

CASE PRESENTATION

We describe a novel kindred with hereditary adrenal cortical carcinoma and the Muir- Torre syndrome, a phenotypic variant of Lynch syndrome that includes sebaceous neoplasms and visceral malignancies. We report a 59-year-old Caucasian man with an MSH2 deletion who was diagnosed with metastatic adrenal cortical carcinoma. The patient's brother also had a history of adrenal cortical carcinoma. The patient's cancer initially responded to immunotherapy with pembrolizumab. Somatic genetic testing performed on a tumor biopsy did not identify the germline MSH2 deletion.

CONCLUSIONS

A review of the literature identifies an association between germline MSH2 mutations and ACC, suggesting a potential biological basis for carcinogenesis. This case highlights the importance of ACC screening for patients with Lynch Syndrome and a family history of adrenal cortical carcinoma due to the high mortality from this malignancy. This case also highlights the importance of separate germline and somatic testing for patients with a concerning personal or family history of cancers.

Molecular Basis of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (NETs) are rare well-differentiated neoplasms with limited therapeutic options and unknown cells of origin. The current classification of pancreatic neuroendocrine tumors is based on proliferative grading, and guides therapeutic strategies, however, tumors within grades exhibit profound heterogeneity in clinical manifestation and outcome. Manifold studies have highlighted intra-patient differences in tumors at the genetic and transcriptomic levels. Molecular classification might become an alternative or complementary basis for treatment decisions and reflect tumor biology, actionable cellular processes. Here, we provide a comprehensive review of genomic, transcriptomic, proteomic and epigenomic studies of pancreatic NETs to elucidate patterns shared between proposed subtypes that could form a foundation for new classification. We denote four NET subtypes with distinct molecular features, which were consistently reproduced using various omics technologies.

Familial Intraductal Papillary Mucinous Neoplasm Associated With the Germline MSH6 Missense Variant and Progression of Pancreatic cancer

OBJECTIVES

Intraductal papillary mucinous neoplasm (IPMN) in individuals with at least one first-degree relative with IPMN is defined as familial IPMN. However, few studies have reported on familial IPMN, its clinical characteristics, or the associated genetic factors.

MATERIALS AND METHODS

We report the case of a 58-year-old woman with multifocal IPMN and a mural nodule in the pancreatic body. The patient underwent a distal pancreatectomy and developed pancreatic head cancer 1 year and 6 months postoperatively. The patient had a family history of multifocal IPMN in her father. Therefore, a genetic predisposition to IPMN and pancreatic cancer was suspected. The patient was analyzed for germline variants, and the resected IPMN was subjected to immunohistochemical and somatic variant analyses.

RESULTS

Next-generation sequencing revealed a heterozygous germline missense variant in exon 5 of MSH6 (c.3197A>G; Tyr1066Cys). The pathogenicity of this variant of uncertain significance was suspected based on multiple in silico analyses, and the same MSH6 variant was identified in the patient's father's colonic adenoma. The mural nodule in the pancreatic body was pathologically diagnosed as a high-grade IPMN with ossification and somatic KRAS and PIK3CA variants.

CONCLUSIONS

This case revealed a possible genetic factor for familial IPMN development and presented interesting clinicopathological findings.

The Role of Germline Mutations in Thoracic Malignancies: Between Myth and Reality

Considering the established contribution of environmental factors to the development of thoracic malignancies, the inherited susceptibility of these tumors has rarely been explored. However, the recent introduction of next-generation sequencing-based tumor molecular profiling in the real-word setting enabled us to deeply characterize the genomic background of patients with lung cancer with or without smoking-related history, increasing the likelihood of detecting germline mutations with potential prevention and treatment implications. Pathogenic germline variants have been detected in 2% to 3% of patients with NSCLC undergoing next-generation sequencing analysis, whereas the proportion of germline mutations associated with the development of pleural mesothelioma widely varies across different studies, ranging between 5% and 10%. This review provides an updated summary of emerging evidence about germline mutations in thoracic malignancies, focusing on pathogenetic mechanisms, clinical features, therapeutic implications, and screening recommendations for high-risk individuals.

The Impact of Germline Alterations in Appendiceal Adenocarcinoma

PURPOSE

More than 10% of assessed patients with appendiceal adenocarcinoma have a pathogenic (P) or likely pathogenic (LP) germline variant, including genes implicated in heritable gastrointestinal cancer syndromes, such as Lynch syndrome. We defined the clinical and molecular impact of heritable alterations in appendiceal adenocarcinoma to evaluate the need for dedicated appendiceal screening and prevention strategies in patients with LP/P germline variants.

EXPERIMENTAL DESIGN

We performed an integrated germline and somatic molecular analysis for patients with confirmed appendiceal adenocarcinoma. Patients underwent paired tumor-normal sequencing for up to 90 hereditary cancer risk genes and 505 genes for somatic mutation profiling. We defined the cooccurrence of LP/P germline variants and second-hit pathogenic somatic alterations. The associations between germline variants and patient clinicopathologic features were also evaluated.

RESULTS

Twenty-five of 237 patients (10.5%) carried pathogenic or likely pathogenic germline variants in cancer susceptibility genes. Clinicopathologic characteristics and appendiceal adenocarcinoma-specific survival were similar in patients with or without germline variants. Most (92%, N = 23/25) patients with germline variants demonstrated no second-hit somatic alterations, including loss of heterozygosity. Two patients with a germline APC I1307K low-penetrance founder variant exhibited secondary somatic pathogenic alterations in APC. However, only one patient tumor exhibited APC-mediated WNT signaling dysregulation: a plausible consequence of multiple somatic APC mutations with no germline variant contribution. Four patients had germline variants in PMS2 or MSH2 associated with Lynch syndrome, yet their cancers were microsatellite-stable.

CONCLUSIONS

Germline variants are likely incidental without a contributory driver role in appendiceal adenocarcinoma. Appendiceal adenocarcinoma screening in patients with germline variants is not clearly merited.

Pathogenic Insights into DNA Mismatch Repair (MMR) Genes-Proteins and Microsatellite Instability: Focus on Adrenocortical Carcinoma and Beyond

DNA damage repair pathways, including mismatch repair (MMR) genes, are prone to carcinoma development in certain patients. The assessment of the MMR system is widely recognized as part of strategies concerning solid tumors (defective MMR cancers), especially MMR proteins (through immunohistochemistry), and molecular assays for microsatellite instability (MSI). We aim to highlight the status of MMR genes-proteins (including MSI) in the relationship with ACC (adrenocortical carcinoma) according to current knowledge. This is a narrative review. We included PubMed-accessed, full-length English papers published between January 2012 and March 2023. We searched studies on ACC patients for whom MMR status was assessed, respectively subjects harboring MMR germline mutations, namely Lynch syndrome (LS), who were diagnosed with ACC. MMR system assessments in ACCs involve a low level of statistical evidence. Generally, there are two main types of endocrine insights: 1. the role of MMR status as a prognostic marker in different endocrine malignancies (including ACC)-which is the topic of the present work, and 2. establishing the indication of immune checkpoint inhibitors (ICPIs) in selective, mostly highly aggressive, non-responsive to standard care forms upon MMR evaluation (which belongs to the larger chapter of immunotherapy in ACCs). Our one-decade, sample-case study (which, to our knowledge, it is the most comprehensive of its kind) identified 11 original articles (from 1 patient to 634 subjects per study diagnosed with either ACC or LS). We identified four studies published in 2013 and 2020 and two in 2021, three cohorts and two retrospective studies (the publication from 2013 includes a retrospective and a cohort distinct section). Among these four studies, patients already confirmed to have LS (N = 643, respective 135) were found to be associated with ACC (N = 3, respective 2), resulting in a prevalence of 0.0046%, with a respective of 1.4% being confirmed (despite not having a large amount of similar data outside these two studies). Studies on ACC patients (N = 364, respective 36 pediatric individuals, and 94 subjects with ACC) showed that 13.7% had different MMR gene anomalies, with a respective of 8.57% (non-germline mutations), while 3.2% had MMR germline mutations (N = 3/94 cases). Two case series included one family, with a respective four persons with LS, and each article introduced one case with LS-ACC. Another five case reports (between 2018 and 2021) revealed an additional five subjects (one case per paper) diagnosed with LS and ACC (female to male ratio of 4 to 1; aged between 44 and 68). Interesting genetic testing involved children with TP53-positive ACC and further MMR anomalies or an MSH2 gene-positive subject with LS with a concurrent germline RET mutation. The first report of LS-ACC referred for PD-1 blockade was published in 2018. Nevertheless, the use of ICPI in ACCs (as similarly seen in metastatic pheochromocytoma) is still limited. Pan-cancer and multi-omics analysis in adults with ACC, in order to classify the candidates for immunotherapy, had heterogeneous results, and integrating an MMR system in this larger and challenging picture is still an open issue. Whether individuals diagnosed with LS should undergo surveillance for ACC has not yet been proven. An assessment of tumor-related MMR/MSI status in ACC might be helpful. Further algorithms for diagnostics and therapy, also taking into consideration innovative biomarkers as MMR-MSI, are necessary.

Inherited Cancer Susceptibility Gene Sequence Variations Among Patients With Appendix Cancer

Importance

Germline sequence variations in APC, BMPR1A, CDH1, CHEK2, EPCAM, MLH1, MSH2, MSH6, MUTYH, PMS2, PTEN, SMAD4, STK11, and TP53 genes are associated with susceptibility to gastrointestinal cancers. As a rare cancer, the evaluation of appendiceal cancer (AC) predisposition has been limited.

Objective

To assess the prevalence and spectrum of inherited cancer susceptibility gene sequence variations in patients with AC and the utility of germline genetic testing for this population.

Design, Setting, and Participants

This cohort study included patients with AC who underwent germline genetic testing of 14 cancer susceptibility genes performed by a clinical testing laboratory between March 1, 2012, and December 31, 2016. Data were analyzed from March to August 2022. Clinical, individual, and family histories were obtained from clinician-completed test requisition forms. Multigene panel testing was performed by targeted custom capture and sequencing and chromosome rearrangement analysis.

Main Outcomes and Measures

The main outcomes were germline sequence variation prevalence and spectrum in patients with AC.

Results

Among the 131 patients with AC in the cohort (90 female [68.7%]), a total of 16 deleterious sequence variations were identified in 15 patients (11.5%). Similarly, when limited to the 74 patients with AC as the first and only primary tumor, a total of 8 patients (10.8%) had at least 1 deleterious sequence variation in a cancer susceptibility gene. Overall, 6 patients (4.6%) had a deleterious sequence variation observed in MUTYH (5 with monoallelic MUTYH and 1 with biallelic MUTYH). All 4 patients with Lynch syndrome (3.1%) had a sequence variation in the MLH1 gene, of whom 3 were aged 50 years or older at AC diagnosis. Five patients (3.8%) had deleterious sequence variations in other cancer predisposition genes (1 with APC [c.3920T>A, p.I1307K], 2 with CHEK2 [c.470T>C, p.I157T], 1 with SMAD4 [c.263 287dup, p.L98IFS*14], and 1 with TP53 [c.524G>A, p.R175H]).

Conclusions and Relevance

In this cohort study, 1 in every 10 patients with AC who underwent testing for hereditary cancer predisposition carried an inherited gene sequence variation associated with cancer susceptibility. Given the high frequency and broad spectrum of germline gene sequence variations, these data suggest that genetic evaluation might be warranted for all patients diagnosed with this rare malignant tumor. A systemic sequencing effort for all patients with AC may also identify cancer vulnerabilities to exploit for therapeutic development in a cancer type for which clinical trials are limited.

Detecting mismatch repair deficiency in solid neoplasms: immunohistochemistry, microsatellite instability, or both?

In managing patients with solid tumors, the value of detecting the status of tumor DNA mismatch repair function is widely recognized. Mismatch repair protein immunohistochemistry and molecular microsatellite instability testing constitute the two major test modalities currently in use, yet each is associated with caveats and limitations that can be consequential. Most notably, the traditional approach of defining mismatch repair protein immunohistochemistry abnormality by complete loss of staining in all tumor cells is evolving. Partial or clonal loss is becoming recognized as a manifestation of gene abnormality; in some cases, such clonal loss is associated with germline pathogenic variants. The current criteria and cutoff values for defining microsatellite instability-high are developed primarily according to colorectal tumors. Non-colorectal cases, and occasionally even colorectal tumors, that are mismatch repair-deficient by immunohistochemistry but not microsatellite instability-high by current standards are being recognized. Emerging data suggest that these immunohistochemistry abnormal / non-microsatellite instability-high cases warrant further genetic workup for Lynch syndrome detection. Whether these tumors respond to immunotherapy is a question still to be addressed. It is imperative that pathologists as well as clinicians and investigators be aware of such intricacies regarding routine immunohistochemistry and microsatellite instability testing and the results they generate. This review summarizes our current understanding of the advantages and limitations of these tests and offer our view on what constitutes the most optimal strategy in test selection and how best to utilize case context to enhance the interpretation of the test results.

Integrative Genomic Tests in Clinical Oncology

Many clinical decisions in oncology practice rely on the presence or absence of an alteration in a single genetic locus, be it a pathogenic variant in a hereditary cancer gene or activating mutation in a drug target. In addition, there are integrative tests that produce continuous variables and evaluate complex characteristics of the entire tumor genome. Microsatellite instability (MSI) analysis identifies tumors with the accumulation of mutations in short repetitive nucleotide sequences. This procedure is utilized in Lynch syndrome diagnostic pipelines and for the selection of patients for immunotherapy. MSI analysis is well-established for colorectal malignancies, but its applications in other cancer types lack standardization and require additional research. Homologous repair deficiency (HRD) indicates tumor sensitivity to PARP inhibitors and some cytotoxic drugs. HRD-related "genomic scars" are manifested by a characteristic pattern of allelic imbalances, accumulation of deletions with flanking homology, and specific mutation signatures. The detection of the genetic consequences of HRD is particularly sophisticated and expensive, as it involves either whole genome sequencing (WGS) or the utilization of large next-generation sequencing (NGS) panels. Tumor mutation burden (TMB) can be determined by whole exome sequencing (WES) or middle-throughput NGS multigene testing. Although TMB is regarded as an agnostic indicator of tumor sensitivity to immunotherapy, the clinical utility of this test is proven only for a few cancer types.

Genomic instability and the link to infertility: A focus on microsatellites and genomic instability syndromes

Infertility is associated to multiple types of different genomic instabilities and is a genetic feature of genomic instability syndromes. While the mismatch repair machinery contributes to the maintenance of genome integrity, surprisingly its potential role in infertility is overlooked. Defects in mismatch repair mechanisms contribute to microsatellite instability and genomic instability syndromes, due to the inability to repair newly replicated DNA. This article reviews the literature to date to elucidate the contribution of microsatellite instability to genomic instability syndromes and infertility. The key findings presented reveal microsatellite instability is poorly researched in genomic instability syndromes and infertility.

Localized Malignant Peritoneal Mesothelioma (LMPeM) in Women: A Clinicopathologic Study of 18 Cases

Localized malignant peritoneal mesothelioma is a rare tumor with limited information in the literature. In this study, we present our experience with 18 cases seen in our hospital over a period of 43 years (1978 to 2021). Patients' median age was 55 years (y) (range: 33 to 79 y) and most of them were Caucasians. Patients presented with abdominal pain (11), ascites and right leg swelling (1), abdominal mass (1), and as incidental finding (1). Thirty percent of patients reported asbestos exposure, and all patients with available information had family history of tumors; a third had personal history of tumors. Seventy-seven percent had some form of abdominopelvic surgery and/or inflammatory process. Most cases had microscopic features typically seen in malignant mesothelioma; however, some cases had confounding features such as signet-ring cells, spindle cells, clear cell changes, and adenomatoid tumor-like appearance. BAP-1 by immunohistochemistry was lost in 1/3 cases. Only 1 patient underwent genetic testing and had an MSH2 germline mutation. Homozygous deletion of CDKN2A by FISH was not found in 1 tested case, although next-generation sequencing identified a CDKN2A pathogenic mutation. 16/18 (88%) had surgical treatment, and some also received adjuvant chemotherapy. The mean overall survival (OS) of our patients was 80.4 months (95% confidence interval: 54.3-106.52); the 3-year OS was 79%, while the 5-year OS was 52.6%. Fifty-three percent of patients had recurrences and 20% had tumor progression. Although the limited sample precludes definitive conclusions, small tumor size, low-grade cytology, and low mitotic index appeared to be associated with an indolent behavior.

Overview of the 2022 WHO Classification of Neuroendocrine Neoplasms

In this review, we detail the changes and the relevant features that are applied to neuroendocrine neoplasms (NENs) in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. Using a question-and-answer approach, we discuss the consolidation of the nomenclature that distinguishes neuronal paragangliomas from epithelial neoplasms, which are divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The criteria for these distinctions based on differentiation are outlined. NETs are generally (but not always) graded as G1, G2, and G3 based on proliferation, whereas NECs are by definition high grade; the importance of Ki67 as a tool for classification and grading is emphasized. The clinical relevance of proper classification is explained, and the importance of hormonal function is examined, including eutopic and ectopic hormone production. The tools available to pathologists for accurate classification include the conventional biomarkers of neuroendocrine lineage and differentiation, INSM1, synaptophysin, chromogranins, and somatostatin receptors (SSTRs), but also include transcription factors that can identify the site of origin of a metastatic lesion of unknown primary site, as well as hormones, enzymes, and keratins that play a role in functional and structural correlation. The recognition of highly proliferative, well-differentiated NETs has resulted in the need for biomarkers that can distinguish these G3 NETs from NECs, including stains to determine expression of SSTRs and those that can indicate the unique molecular pathogenetic alterations that underlie the distinction, for example, global loss of RB and aberrant p53 in pancreatic NECs compared with loss of ATRX, DAXX, and menin in pancreatic NETs. Other differential diagnoses are discussed with recommendations for biomarkers that can assist in correct classification, including the distinctions between epithelial and non-epithelial NENs that have allowed reclassification of epithelial NETs in the spine, in the duodenum, and in the middle ear; the first two may be composite tumors with neuronal and glial elements, and as this feature is integral to the duodenal lesion, it is now classified as composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). The many other aspects of differential diagnosis are detailed with recommendations for biomarkers that can distinguish NENs from non-neuroendocrine lesions that can mimic their morphology. The concepts of mixed neuroendocrine and non-neuroendocrine (MiNEN) and amphicrine tumors are clarified with information about how to approach such lesions in routine practice. Theranostic biomarkers that assist patient management are reviewed. Given the significant proportion of NENs that are associated with germline mutations that predispose to this disease, we explain the role of the pathologist in identifying precursor lesions and applying molecular immunohistochemistry to guide genetic testing.

Clinically actionable findings on surveillance EGD in asymptomatic patients with Lynch syndrome

BACKGROUND AND AIMS

Lynch syndrome (LS) predisposes patients to multiple cancers including of the gastric and small bowel. Data supporting EGD surveillance in LS are limited. Our aim is to describe upper GI (UGI) findings in asymptomatic LS patients undergoing EGD surveillance within a hereditary colorectal cancer registry.

METHODS

Asymptomatic patients with LS who underwent ≥1 surveillance EGD were included. Demographics, genotype, and EGD findings were reviewed. The frequency of clinically actionable findings including neoplasia (cancer, adenomas), Barrett's esophagus (BE), Helicobacter pylori, and hyperplastic polyps >5 mm were assessed.

RESULTS

Three hundred twenty-three patients underwent 717 EGDs starting at a median age of 49.5 years. On average, each patient had 2 EGDs with an interval of 2.3 years between examinations. Clinically actionable findings were identified in 57 patients (17.6%). On baseline EGD 27.7% of findings were identified, with the remainder on surveillance EGD over an average of 3.5 years. Five asymptomatic patients (1.5%) had an UGI cancer detected during surveillance, all at early stage, including 1 patient each with BE-related esophageal adenocarcinoma, gastric neuroendocrine tumor, and gastric adenocarcinoma and 2 patients with duodenal adenocarcinoma. Two cancers were found on baseline EGD and 3 on follow-up EGD.

CONCLUSIONS

Clinically actionable findings were found in approximately 1 in 6 asymptomatic patients with LS undergoing EGD surveillance. Five patients (1.5%) were diagnosed with cancer, all detected at an early stage. These data suggest that both baseline and follow-up EGD surveillance are effective in detecting early-stage UGI cancers in asymptomatic patients with LS.

Disorders of the adrenal cortex: Genetic and molecular aspects

Adrenal cortex produces glucocorticoids, mineralocorticoids and adrenal androgens which are essential for life, supporting balance, immune response and sexual maturation. Adrenocortical tumors and hyperplasias are a heterogenous group of adrenal disorders and they can be either sporadic or familial. Adrenocortical cancer is a rare and aggressive malignancy, and it is associated with poor prognosis. With the advance of next-generation sequencing technologies and improvement of genomic data analysis over the past decade, various genetic defects, either from germline or somatic origin, have been unraveled, improving diagnosis and treatment of numerous genetic disorders, including adrenocortical diseases. This review gives an overview of disorders associated with the adrenal cortex, the genetic factors of these disorders and their molecular implications.

Using Immunohistochemistry to Expand the Spectrum of Lynch Syndrome-Related Tumors

The most common genetic and molecular process leading to sporadic colorectal cancer is chromosomal instability. By contrast, mismatch repair deficiency, which results in high levels of microsatellite instability or lack of mismatch repair (MMR) protein expression on immunohistochemistry (IHC), is the predominant cancer pathway in patients with Lynch syndrome (LS). Importantly, patients with LS may still develop sporadic tumors through chromosomal instability. Testing tumors with IHC staining helps expand the spectrum of LS-related tumors. In this series, we describe 4 cancers in patients with LS that are not typical of the syndrome. Lack of MMR protein expression on IHC staining confirmed that 2 cancers are related to LS, expanding the spectrum of LS-related tumors, and the presence of MMR protein expression on IHC in the other 2 cases confirmed that they were sporadic and not related to mismatch repair deficiency and, thus, not related to LS.

Pituitary neuroendocrine tumors: a model for neuroendocrine tumor classification

The classification of adenohypophysial neoplasms as "pituitary neuroendocrine tumors" (PitNETs) was proposed in 2017 to reflect their characteristics as epithelial neuroendocrine neoplasms with a spectrum of clinical behaviors ranging from small indolent lesions to large, locally invasive, unresectable tumors. Tumor growth and hormone hypersecretion cause significant morbidity and mortality in a subset of patients. The proposal was endorsed by a WHO working group that sought to provide a unified approach to neuroendocrine neoplasia in all body sites. We review the features that are characteristic of neuroendocrine cells, the epidemiology and prognosis of these tumors, as well as further refinements in terms used for other pituitary tumors to ensure consistency with the WHO framework. The intense study of PitNETs has provided information about the importance of cellular differentiation in tumor prognosis as a model for neuroendocrine tumors in different locations.

Rare DNA Mismatch Repair-Related Protein Loss in Patients with Intrahepatic Cholangiocarcinoma and Combined Hepatocellular-Cholangiocarcinoma and Their Response to Immunotherapy

Purpose

The patients with advanced mismatch repair deficiency (dMMR) cancers can benefit from programmed cell death 1 (PD-1) pathway blockade, regardless of the tumor type. Little is known about the prevalence of dMMR in intrahepatic cholangiocarcinoma (ICC) and combined hepatocellular-cholangiocarcinoma (cHCC-CC). This study aimed to assess the mismatch repair (MMR)-related protein expression in patients with ICC and cHCC-CC.

Patients and Methods

Formalin-fixed, paraffin-embedded tumor specimens were obtained from patients undergoing surgery at the West china Hospital between 2009 and 2017. The immunoreactions for MLH1, MSH2, MSH6, and PMS2 were investigated to determine the MMR status.

Results

A total of 97 patients were evaluated, including 73 ICC patients and 24 cHCC-CC patients. The prevalence of dMMR was only found in two cases of 97 patients (2.06%). Both patients are ICC. In 24 cHCC-CC patients, no dMMR was observed. They did not receive an adjuvant chemotherapy after surgery. At the end of the follow-up, one patient was in a tumor-free state, and the other patient had local recurrence and metastasis. After receiving sintilimumab (an immune checkpoint inhibitor [ICI] for PD- 1), the patient had a partial response.

Conclusion

DMMR was detected in few patients with ICC and cHCC-CC. Thus, it is not recommended to routinely evaluate the MMR status of patients with ICC or cHCC-CC after surgery, but that of patients with advanced ICC or cHCC-CC should be assessed.

Papillary Renal Cell Carcinoma in Lynch/Muir-Torre Syndrome with Germline Pathogenic Variant in MSH6 and Molecular Analysis: Report of a Case and Review of the Literature

Lynch syndrome (LS) is an autosomal dominant inherited disorder due to pathogenic variations in the mismatch repair genes, which predisposes to malignancies, most commonly colon and endometrial carcinoma. Muir-Torre syndrome is a subset of LS with cutaneous sebaceous adenoma and keratoacanthoma in addition to the malignancies. Renal cell carcinoma (RCC) in patients with LS is extremely rare. Only 26 cases have been reported and among them, only two cases of papillary RCC. We report a case of synchronous papillary RCC and colonic adenocarcinoma in an 85-year-old male with Lynch/Muir-Torre syndrome. The LS was diagnosed when he presented with multiple sebaceous adenomas and genetic testing showed a pathogenic variant in MSH6 mismatch repair gene. A colonoscopy at that time showed multiple tubular adenomas with high-grade dysplasia. He was lost to follow-up and presented with gastrointestinal bleeding after 20 years. A right colonic mass, and a solid mass in the lower pole of the right kidney, was detected by imaging. Right Colectomy showed a T3N0 mucin-producing adenocarcinoma. Right nephrectomy showed a T3a papillary RCC which was microsatellite stable with MSH6, and KRAS mutation. The 36-month follow-up exams showed additional sebaceous neoplasms, and an absence of metastatic carcinoma. Analysis of the reported cases of RCC in LS show clear cell RCC as the most common type. These tumors showed MLH1 mutation most commonly, unlike the urothelial malignancies in LS which involve MSH2. Among the 4 cases of RCC with MSH6 mutation, three were in females, indicating some gender differences.

Primary Peritoneal Low-grade Serous Carcinoma in a Patient With Lynch Syndrome: A Case Report

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 treated with total hysterectomy and bilateral salpingo-oophorectomy 14 yr ago. During the follow-up, peritoneal nodules were detected by abdominal computed tomography which were surgically resected. Pathologic examination revealed a low-grade serous carcinoma with cells positive for BerEP4, MOC31, CEA, and WT-1 and negative for BAP1, PAX8, MLH1, and PMS2, by immunohistochemistry. This case report and literature review show that peritoneal low-grade serous carcinoma can occur in patients with LS and that LS-related cancers usually precede primary peritoneal malignancies. The differential diagnosis for peritoneal nodules in patients with LS should, therefore, include peritoneal serous carcinoma and malignant mesothelioma besides metastasis of LS-related cancers. Considering the ambiguous immunophenotypes, a combination of immunohistologic markers would be useful for an accurate diagnosis of such cases.

Mismatch Repair Deficiency and Microsatellite Instability in Triple-Negative Breast Cancer: A Retrospective Study of 440 Patients

Purpose

To investigate the status of mismatch repair (MMR) and microsatellite instability (MSI) in triple-negative breast cancer (TNBC) and to examine correlations between MMR/MSI status and clinicopathological parameters.

Methods

We retrospectively collected tissue samples from 440 patients with TNBC and constructed tissue microarrays. Protein expression of MLH1, MSH2, MSH6, and PMS2 was detected by immunohistochemistry (IHC). We also analyzed 195 patient samples using MSI polymerase chain reaction (PCR) testing. Correlations between MSI status and clinicopathological parameters and prognosis were analyzed.

Results

The median age of the cohort was 49 years (range: 24–90 years) with a median follow-up period of 68 months (range: 1–170 months). All samples were positive for MLH1, MSH2, MSH6, and PMS2, except for one sample identified as MMR-deficient (dMMR) by IHC, with loss of MSH2 and intact MSH6 expression. MSI PCR revealed no case with high-frequency MSI (MSI-H), whereas 14 (7.2%) and 181 (92.8%) samples demonstrated low-frequency and absence of MSI events, respectively. The dMMR sample harbored low-frequency instability, as revealed by MSI PCR, and a possible EPCAM deletion in the tumor, as observed from next-generation sequencing. No correlations were detected between MMR or MSI status and clinicopathological parameters, programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) expression, or survival.

Conclusions

The incidence of dMMR/MSI-H is extremely low in TNBC, and rare discordant MSI PCR/MMR IHC results may be encountered. Moreover, MMR/MSI status may be of limited prognostic value. Further studies are warranted to explore other predictive immunotherapy biomarkers for TNBC.

Molecular Pathology of Well-Differentiated Gastro-entero-pancreatic Neuroendocrine Tumors

Well differentiated neuroendocrine tumors (NETs) arising in the gastrointestinal and pancreaticobiliary system are the most common neuroendocrine neoplasms. Studies of the molecular basis of these lesions have identified genetic mutations that predispose to familial endocrine neoplasia syndromes and occur both as germline events and in sporadic tumors. The mutations often involve epigenetic regulators rather than the oncogenes and tumor suppressors that are affected in other malignancies. Somatic copy number alterations and miRNAs have also been implicated in the development and progression of some of these tumors. The molecular profiles differ by location, but many are shared by tumors in other sites, including those outside the gastroenteropancreatic system. The approach to therapy relies on both the neuroendocrine nature of these tumors and the identification of specific alterations that can serve as targets for precision oncologic approaches.

The diversity of tumours with microsatellite instability: molecular mechanisms and impact upon microsatellite instability testing and mismatch repair protein immunohistochemistry

Microsatellite instability (MSI) as a distinct molecular phenotype in human neoplasms was first recognised in 1993. Since then there has been tremendous progress in our understanding of this phenotype, including its genomic drivers and functional consequences. Currently, the multiple lines of investigation on MSI seem to have converged upon one important facet: its diversity, both genotypically and phenotypically, and both within and across tumour types. This review article offers a pathologist's perspective on our current understanding of this diversity, and highlights its potentially significant impact on the effective use of our current MSI detection tools: PCR- or sequencing-based MSI testing and mismatch repair protein immunohistochemistry.

Characteristics of Adrenocortical Carcinoma Associated With Lynch Syndrome

CONTEXT

Lynch syndrome (LS) is the most common inherited colorectal and endometrial cancer syndrome, caused by germline mutations in DNA mismatch repair (MMR) genes. It is also characterized by an increased risk of other tumors with lower prevalence, such as adrenal cortical carcinoma (ACC), an endocrine tumor with an incidence of <2 cases/million individuals/year. Most ACC developed during childhood are associated with hereditary syndromes. In adults, this association is not as well established as in children. Previous studies showed a 3.2% prevalence of LS among patients with ACC.

EVIDENCE ACQUISITION

The objective of this study is to determine the prevalence of ACC in a Spanish LS cohort and their molecular and histological characteristics. This retrospective study includes 634 patients from 220 LS families registered between 1999 and 2018.

EVIDENCE SYNTHESIS

During the follow-up period, 3 patients were diagnosed with ACC (0.47%); all were carriers of a MSH2 germline mutation. The 3 ACC patients presented loss of expression of MSH2 and MSH6 proteins. One tumor analysis showed loss of heterozygosity of the MSH2 wildtype allele. Our findings support previous data that considered ACC as a LS spectrum tumor.

CONCLUSION

MMR protein immunohistochemistry screening could be an efficient strategy to detect LS in patients with ACC.

Malignant Mesothelioma of the Peritoneum in Women: A Clinicopathologic Study of 164 Cases

Malignant mesothelioma of the peritoneum in women is an uncommon tumor. In this study, we present the clinicopathologic features of 164 such cases seen in our institution over a period of 42 years (1974-2016). Clinical information, pathologic findings, immunohistochemical results, and follow-up were recorded. Hematoxylin and eosin-stained slides were reviewed in all cases. Patients ranged in age from 3 to 85 years, median: 49 years. Most patients presented with abdominal/pelvic pain, although some were asymptomatic, presented with paraneoplastic syndromes or cervical lymphadenopathy. Overall, 9% of patients had a history of direct or indirect exposure to asbestos. In total, 31% and 69% of patients had either a personal or family history of other tumors; most of these tumors are currently recognized as part of a syndrome. Genetic testing information was available in 5 patients: BAP-1 germline mutation (1), type 2 neurofibromatosis (1), Lynch syndrome (1), McCune-Albright syndrome (1), no BAP-1 or TP53 mutation (1). Most cases had gross and microscopic features typical of malignant mesothelioma of the peritoneum in women; however, some had confounding features such as gelatinous appearance, signet ring or clear cells, and well-differentiated papillary mesothelioma-like areas. Calretinin and WT-1 were the markers more frequently expressed, and up to 23% of the cases showed PAX-8 expression. Patients' treatments predominantly included: chemotherapy, cytoreductive surgery, and hyperthermic intraperitoneal chemotherapy. On multivariate analysis, the predominance of deciduoid cells, nuclear grade 3, and the absence of surgical treatment were associated with worse overall survival (OS). For all patients, the 3- and 5-year OS were 74.3% and 57.4%, respectively. The 3- and 5-year OS for patients treated with cytoreductive surgery, and hyperthermic intraperitoneal chemotherapy were 88.9% and 77.8%, respectively.

Immune-Based Therapies and the Role of Microsatellite Instability in Pancreatic Cancer

Pancreatic cancer is one of the most aggressive malignancies with limited treatment options thus resulting in high morbidity and mortality. Among all cancers, with a five-year survival rates of only 2-9%, pancreatic cancer holds the worst prognostic outcome for patients. To improve the overall survival, an earlier diagnosis and stratification of cancer patients for personalized treatment options are urgent needs. A minority of pancreatic cancers belong to the spectrum of Lynch syndrome-associated cancers and are characterized by microsatellite instability (MSI). MSI is a consequence of defective mismatch repair protein functions and it has been well characterized in other gastrointestinal tumors such as colorectal and gastric cancer. In the latter, high levels of MSI are linked to a better prognosis and to an increased benefit to immune-based therapies. Therefore, the same therapies could offer an opportunity of treatment for pancreatic cancer patients with MSI. In this review, we summarize the current knowledge about immune-based therapies and MSI in pancreatic cancer.

Germline EGFR variants are over-represented in adolescents and young adults (AYA) with adrenocortical carcinoma

Adrenocortical Carcinoma (ACC) is a rare endocrine tumor with poor overall prognosis and 1.5-fold overrepresentation in females. In children, ACC is associated with inherited cancer syndromes with 50-80% of childhood-ACC associated with TP53 germline variants. ACC in adolescents and young adults (AYA) is rarely due to germline TP53, IGF2, PRKAR1A and MEN1 variants. We analyzed exome sequencing data from 21 children (<15y), 32 AYA (15-39y), and 60 adults (>39y) with ACC, and retained all pathogenic, likely pathogenic, and highly prioritized variants of uncertain significance. We engineered a stable lentiviral-mutant ACC cell line, harboring an EGFR variant (p.Asp1080Asn) from a 21-year-old female without germline-TP53-variant and with aggressive ACC. We found that 4.8% of the children (P = 0.004) and 6.2% of AYA (P < 0.0001), all-female participants, harbored germline EGFR variants, compared to only 0.3% of the control group. Expanding our analysis to the RTK-RAS-MAPK pathway, we found that the RTK genes have the highest number of highly prioritized germline variants in these individuals amongst all three arms of this pathway. We showed EGFR mutant cells migrate faster and are characterized by a stem-like phenotype compared to wild type cells. While EGFR inhibitors did not affect the stemness of mutant cells, Sunitinib, a multireceptor tyrosine kinase inhibitor, significantly reduced their stem-like behavior. Our data suggest that EGFR could be a novel underlying germline predisposition factor for ACC, especially in the Childhood-AYA (C-AYA) population. Further clinical validation can improve precision oncology management of this disease, which is known to have limited therapeutic options.

Long Survival and Prolonged Remission after Surgery and Chemotherapy in a Metastatic Mismatch Repair Deficient Pancreatic Neuroendocrine Carcinoma with MLH1/PMS2 Immunodeficiency and Minimal Microsatellite Shift

Pancreatic neuroendocrine carcinomas (NECs) are rare and very aggressive neoplasms with dismal prognosis, especially when metastatic or with negative prognostic factors, such as vascular invasion. To the best of our knowledge, no case of pancreatic NEC with mismatch repair deficiency has been reported to date. We describe a 62-year-old patient who underwent pancreaticoduodenectomy for a NEC located in the pancreatic head, with peripancreatic lymph node metastases. Tumor necrosis was prominent and the Ki67 proliferative index was 60%. One year after the diagnosis, the patient experienced recurrence with a left supraclavicular lymph node metastasis, which was surgically removed, followed by standard cisplatin-etoposide chemotherapy. Neoplastic cells showed combined loss of expression of MLH1 and PMS2 in both primary tumor and lymph node metastasis. Microsatellite instability (MSI) test using a mononucleotide repeats pentaplex PCR (BAT-25, BAT-26, NR-21, NR-22, and NR-24) revealed minimal mononucleotide shifts showing deletion of less than 3 bp at NR-21, BAT-26, NR-24, and NR-22 loci. MLH1 methylation analysis revealed absence of the gene promoter methylation. BRAF and KRAS mutations were not detected. In gut, NECs' mismatch repair deficiency phenotype has been reported in about 10% of cases, and it represents an independent factor of more favorable outcome. Likewise, our patient is currently alive with a follow-up of more than 12 years after pancreaticoduodenectomy, by itself an unexpected finding for such an aggressive neoplasm.

Is DNA repair a potential target for effective therapies against malignant mesothelioma?

Malignant pleural mesothelioma (MPM) is a rare malignancy mainly caused by asbestos exposure. Germinal and acquired mutations in genes of DNA repair pathways, in particular of homologous recombination repair, are frequent in MPM. Here we overview the available experimental data suggesting that an impaired DNA repair system affects MPM pathogenesis by leaving lesions through the genome unresolved. DNA repair defects represent a vulnerability of MPM, and it seems plausible to propose that leveraging these deficiencies could have therapeutic potential for patients with MPM, for whom there is an urgent need of more effective therapies.

Inherited Genetic Mutations and Polymorphisms in Malignant Mesothelioma: A Comprehensive Review

Malignant mesothelioma (MM) is mainly caused by air-born asbestos but genetic susceptibility is also suspected to be a risk factor. Recent studies suggest an increasing number of candidate genes that may predispose to MM besides the well-characterized BRCA1-associated protein-1 gene. The aim of this review is to summarize the most important studies on germline mutations for MM. A total of 860 publications were retrieved from Scopus, PubMed and Web of Science, of which 81 met the inclusion criteria and were consider for this review. More than 50% of the genes that are reported to predispose to MM are involved in DNA repair mechanisms, and the majority of them have a role in the homologous recombination pathway. Genetic alterations in tumor suppressor genes involved in chromatin, transcription and hypoxia regulation have also been described. Furthermore, we identified several single nucleotide polymorphisms (SNPs) that may promote MM tumorigenesis as a result of an asbestos-gene interaction, including SNPs in DNA repair, carcinogen detoxification and other genes previously associated with other malignancies. The identification of inherited mutations for MM and an understanding of the underlying pathways may allow early detection and prevention of malignancies in high-risk individuals and pave the way for targeted therapies.

Lynch syndrome and urologic malignancies: a contemporary review

PURPOSE OF REVIEW

An overview of urologic malignancies in Lynch syndrome and the current state of research.

RECENT FINDINGS

Upper tract urothelial carcinoma (UTUC) is the third most common malignancy in Lynch syndrome. Establishment and utilization of a sensitive and practical screening method for Lynch syndrome in patients presenting with UTUC is overdue. Next-generation sequencing to evaluate for microsatellite instability (MSI) and detect mutations of mismatch repair (MMR) genes may be the future of Lynch syndrome screening. Epidemiologic data and molecular characterization suggest bladder urothelial carcinoma (BUC) and prostate cancer (PCA) as unrecognized components of Lynch syndrome. Small studies suggest that Lynch syndrome may predispose individuals to adrenocortical carcinoma. Testicular cancer literature focuses on characterizing MSI and MMR gene expression as it relates to chemotherapy sensitivity; outcomes suggest a potential avenue to investigate its relationship to Lynch syndrome.

SUMMARY

Patients with Lynch syndrome have an increased risk of urologic malignancies, including UTUC and likely BUC and PCA. BUC and PCA have a lower penetrance than UTUC for unknown reasons. Established Lynch syndrome-associated genitourinary tumors will necessitate the development of methods to diagnose Lynch syndrome in patients presenting with these malignancies, in addition to establishing screening guidelines for patients with Lynch syndrome-associated genitourinary tumors.

PD-1 Blockade in Advanced Adrenocortical Carcinoma

PURPOSE

Adrenocortical carcinomas (ACC) are rare and aggressive malignancies with limited treatment options. This study was undertaken to evaluate the immunogenicity of ACC.

PATIENTS AND METHODS

Patients with advanced ACC were enrolled in a phase II study to evaluate the clinical activity of pembrolizumab 200 mg every 3 weeks, without restriction on prior therapy. The primary end point was objective response rate. Efficacy was correlated with tumor programmed death-ligand 1 expression, microsatellite-high and/or mismatch repair deficient (MSI-H/MMR-D) status, and somatic and germline genomic correlates.

RESULTS

We enrolled 39 patients with advanced ACC and herein report after a median follow-up of 17.8 months (range, 5.4 months to 34.7 months). The objective response rate to pembrolizumab was 23% (nine patients; 95% CI, 11% to 39%), and the disease control rate was 52% (16 patients; 95% CI, 33% to 69%). The median duration of response was not reached (lower 95% CI, 4.1 months). Two of six patients with MSI-H/MMR-D tumors responded. The other seven patients with objective responses had microsatellite stable tumors. The median progression-free survival was 2.1 months (95% CI, 2.0 months to 10.7 months), and the median overall survival was 24.9 months (95% CI, 4.2 months to not reached). Thirteen percent of patients (n = 5) had treatment-related grade 3 or 4 adverse events. Tumor programmed death-ligand 1 expression and MSI-H/MMR-D status were not associated with objective response.

CONCLUSION

MSI-H/MMR-D tumors, for which pembrolizumab is a standard therapy, are more common in ACC than has been recognized. In advanced ACC that is microsatellite stable, pembrolizumab provided clinically meaningful and durable antitumor activity with a manageable safety profile.

Neuroendocrine Neoplasms Associated with Germline Pathogenic Variants in the Homologous Recombination Pathway

Neuroendocrine neoplasms (NENs) have been primarily associated with germline pathogenic variants in genes involved in chromatin remodeling (MEN1), cell cycle control (CDKN1B), PI3K/mTOR signaling (TSC1/2, PTEN) as well as pseudohypoxia (VHL, SDHx). Recent work has implicated various genes involved in DNA repair pathways in the pathophysiology of a subset of pancreatic neuroendocrine neoplasms, including BRCA2, via the homologous recombination pathway (HRD). To date, germline variants in other HRD pathway genes have not been described to contribute to NEN. PALB2, RAD51C, and BARD1 are additional tumor suppressor genes which also mediate repair of double stranded DNA breaks through the HRD pathway and are implicated in hereditary breast (PALB2; BARD1) and ovarian (RAD51C) cancer. Here we report three cases of NEN associated with germline pathogenic variants in PALB2 (pancreatic NEN), RAD51C (thymic NEN), and BARD1 (pancreaticoduodenal NEN) respectively, further linking the DNA repair pathway to NENs.

Malignant mesothelioma in Lynch syndrome: A report of two cases and a review of the literature

Malignant mesothelioma is a rare and aggressive cancer most typically associated with prior asbestos exposure. The nature of the relationship between asbestos exposure and hereditary familial syndromes predisposing to malignancy has not been determined. We report two Lynch syndrome patients with paraoccupational asbestos exposure who developed diffuse malignant mesothelioma of the pleura or peritoneum. Interestingly, one showed a separate focus of pleural well-differentiated papillary mesothelioma. It is likely that Lynch syndrome patients are at increased risk for the development of mesothelioma in the setting of exposure to asbestos, even at what is generally considered to be low levels. In the presence of a documented history of low-level asbestos exposure, patients with genetic predisposition disorders (including Lynch syndrome) should be considered to have an independent risk factor modifying the effects of asbestos exposure.

Adrenal Cortical Carcinoma Associated With Lynch Syndrome: A Case Report and Review of Literature

Objective

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. ACC was reported in 3.2% patients with Lynch syndrome (LS), however no particular case-detection strategies have been recommended.

Participants

We report a case of a 65-year-old woman who was incidentally discovered with a large adrenal mass during work-up of postmenopausal uterine bleeding. She was recently diagnosed with MSH6 germline mutation after her sister presented with uterine carcinoma in the setting of LS.

Results

Whereas the patient was asymptomatic for overt hormonal excess, biochemical work-up confirmed glucocorticoid autonomy and androgen and estrogen excess. Urine steroid profiling was suggestive of ACC. Adrenalectomy confirmed an oncocytic ACC with focal extracapsular extension into the periadrenal adipose tissue with a Ki-67 of 15% and a peak mitotic count of 40/50 high-power fields.

Conclusion

ACC can be the only manifestation of LS. A best case-detection approach for ACC in the asymptomatic patient with LS is unclear, however urine steroid profiling could be considered.

Frequency of Germline Mutations in Cancer Susceptibility Genes in Malignant Mesothelioma

PURPOSE

The aim of the current study was to determine the prevalence and clinical predictors of germline cancer susceptibility mutations in patients with malignant mesothelioma (MM).

METHODS

We performed targeted capture and next-generation sequencing of 85 cancer susceptibility genes on germline DNA from 198 patients with pleural, peritoneal, and tunica vaginalis MM.

RESULTS

Twenty-four germline mutations were identified in 13 genes in 23 (12%) of 198 patients. BAP1 mutations were the most common (n = 6; 25%). The remaining were in genes involved in DNA damage sensing and repair (n = 14), oxygen sensing (n = 2), endosome trafficking (n = 1), and cell growth (n = 1). Pleural site (odds ratio [OR], 0.23; 95% CI, 0.10 to 0.58; P < .01), asbestos exposure (OR, 0.28; 95% CI, 0.11 to 0.72; P < .01), and older age (OR, 0.95; 95% CI, 0.92 to 0.99; P = .01) were associated with decreased odds of carrying a germline mutation, whereas having a second cancer diagnosis (OR, 3.33; 95% CI, 1.22 to 9.07; P = .02) significantly increased the odds. The odds of carrying a mutation in BAP1 (OR, 1,658; 95% CI, 199 to 76,224; P < .001), BRCA2 (OR, 5; 95% CI, 1.0 to 14.7; P = .03), CDKN2A (OR, 53; 95% CI, 6 to 249; P < .001), TMEM127 (OR, 88; 95% CI, 1.7 to 1,105; P = .01), VHL (OR, 51; 95% CI, 1.1 to 453; P = .02), and WT1 (OR, 20; 95% CI, 0.5 to 135; P = .049) were significantly higher in MM cases than in a noncancer control population. Tumor sequencing identified mutations in a homologous recombination pathway gene in 52% (n = 29 of 54).

CONCLUSION

A significant proportion of patients with MM carry germline mutations in cancer susceptibility genes, especially those with peritoneal MM, minimal asbestos exposure, young age, and a second cancer diagnosis. These data support clinical germline genetic testing for patients with MM and provide a rationale for additional investigation of the homologous recombination pathway in MM.

Mismatch Repair Protein Defects and Microsatellite Instability in Malignant Pleural Mesothelioma

INTRODUCTION

Malignant pleural mesothelioma is an aggressive malignancy with limited systemic therapy options. Promising results have been reported with use of anti-programmed cell death 1 therapy; however, its benefits appear to be confined to a subgroup of patients. Microsatellite instability (MSI) results from the inactivation of DNA mismatch repair genes and results in a high tumor mutational burden, a phenomenon that has not been seen with mesothelioma. MSI and protein absence have been shown to correlate in colorectal cancer, such that most centers have adopted immunohistochemistry (IHC) to screen for MSI-high colorectal cancers. We profiled a large cohort of patients with mesothelioma to determine the rate of negative IHC staining results the four common mismatch repair proteins.

DESIGN

A tissue microarray comprising 335 patients with malignant pleural mesothelioma were used. IHC for the four common mismatch repair proteins (mutL homolog 1; PMS1 homolog 2, mismatch repair system component; mutS homolog 2; and mutS homolog 6) was performed. Programmed death ligand 1 IHC staining with the E1L3N clone was also performed. DNA was isolated from IHC equivocal samples and analyzed for microsatellite instability by using the Promega MSI Analysis System (version 1.2, Promega, Madison, WI).

RESULTS

Of the patients profiled, 329 had intact mismatch repair proteins by IHC. Six samples with IHC testing results indicating absent mismatch repair protein were analyzed for MSI and confirmed to be negative. Of the six IHC-negative samples, five were negative for programmed death ligand 1 staining and one sample had more than 5% staining.

CONCLUSION

In this large retrospective series, we were unable to identify any patients with malignant pleural mesothelioma with microsatellite instability. Response to anti-programmed cell death 1-based immunotherapy may be driven by other mechanisms.

High throughput gene sequencing reveals altered landscape in DNA damage responses and chromatin remodeling in sporadic pancreatic neuroendocrine tumors

PURPOSE

The main objectives of this retrospective study were to survey the genetic landscape of PNETs in a clinical cohort by using the high throughput gene sequencing method and to determine cellular signaling networks affected by the uncovered gene mutations.

MATERIALS AND METHODS

We retrieved the demographics and tumor characteristics of 13 patients. Cellular DNA was extracted from fresh snap frozen tumor tissues and was subject to high throughput gene sequencing analysis using the Illumina NextSeq500 System. Furthermore, the interaction network was constructed from the input gene set by Reactome and performed gene set enrichment analysis was performed with a cutoff FDR of ≤0.01.

RESULTS

Totally 74 mutated genes and 93 mutations were identified. The median number of mutations was 7 (range 1-20) and that of mutated genes was 6 (range 1-17). Among these mutations, 48 (51.6%) were substitution mutations, nine (9.7%) were duplication mutations, 28 (30.1%) were deletion mutations and eight (8.6%) were deletion/insertion mutations. Gene set enrichment analysis generated a network of 21 interactions, 10 of which were associated with DNA repair like the Fanconi anemia pathway, nucleotide excision repair, and homologous recombination repair, or chromosome maintenance. Moreover, 9 patients had one or more mutations in DNA repair genes including the mismatch repair genes MSH2/MSH6.

CONCLUSIONS

The study has uncovered genetic alterations of genes implicated in DNA damage responses and chromatin remodeling. Our findings will prompt further studies into the role of these mutated genes in the oncogenesis and molecular stratification of PNETs.

Evaluating Mismatch Repair Deficiency in Pancreatic Adenocarcinoma: Challenges and Recommendations

Purpose: Immune checkpoint inhibition has been shown to generate profound and durable responses in mismatch repair deficient (MMR-D) solid tumors and has elicited interest in detection tools and strategies to guide therapeutic decision-making. Herein we address questions on the appropriate screening, detection methods, patient selection, and initiation of therapy for MMR-D pancreatic ductal adenocarcinoma (PDAC) and assess the utility of next-generation sequencing (NGS) in providing additional prognostic and predictive information for MMR-D PDAC.Experimental Design: Archival and prospectively acquired samples and matched normal DNA from N = 833 PDAC cases were analyzed using a hybridization capture-based, NGS assay designed to perform targeted deep sequencing of all exons and selected introns of 341 to 468 cancer-associated genes. A computational program using NGS data derived the MSI status from the tumor-normal paired genome sequencing data. Available germline testing, IHC, and microsatellite instability (MSI) PCR results were reviewed to assess and confirm MMR-D and MSI status.Results: MMR-D in PDAC is a rare event among PDAC patients (7/833), occurring at a frequency of 0.8%. Loss of MMR protein expression by IHC, high mutational load, and elevated MSIsensor scores were correlated with MMR-D PDAC. All 7 MMR-D PDAC patients in the study were found to have Lynch syndrome. Four (57%) of the MMR-D patients treated with immune checkpoint blockade had treatment benefit (1 complete response, 2 partial responses, 1 stable disease).Conclusions: An integrated approach of germline testing and somatic analyses of tumor tissues in advanced PDAC using NGS may help guide future development of immune and molecularly directed therapies in PDAC patients. Clin Cancer Res; 24(6); 1326-36. ©2018 AACR.

Genetics of tumors of the adrenal cortex

This review describes the molecular alterations observed in the various types of tumors of the adrenal cortex, excluding Conn adenomas, especially the alterations identified by genomic approaches these last five years. Two main forms of bilateral adrenocortical tumors can be distinguished according to size and aspect of the nodules: primary pigmented nodular adrenal disease (PPNAD), which can be sporadic or part of Carney complex and primary bilateral macro nodular adrenal hyperplasia (PBMAH). The bilateral nature of the tumors suggests the existence of an underlying genetic predisposition. PPNAD and Carney complex are mainly due to germline-inactivating mutations of PRKAR1A, coding for a regulatory subunit of PKA, whereas PBMAH genetic seems more complex. However, genome-wide approaches allowed the identification of a new tumor suppressor gene, ARMC5, whose germline alteration could be responsible for at least 25% of PBMAH cases. Unilateral adrenocortical tumors are more frequent, mostly adenomas. The Wnt/beta-catenin pathway can be activated in both benign and malignant tumors by CTNNB1 mutations and by ZNRF3 inactivation in adrenal cancer (ACC). Some other signaling pathways are more specific of the tumor dignity. Thus, somatic mutations of cAMP/PKA pathway genes, mainly PRKACA, coding for the catalytic alpha-subunit of PKA, are found in cortisol-secreting adenomas, whereas IGF-II overexpression and alterations of p53 signaling pathway are observed in ACC. Genome-wide approaches including transcriptome, SNP, methylome and miRome analysis have identified new genetic and epigenetic alterations and the further clustering of ACC in subgroups associated with different prognosis, allowing the development of new prognosis markers.

Triple primary malignancies in a patient with colorectal adenocarcinoma: A case report

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A 55-year-old male patient was found to have triple primary malignancies, suspected to be lynch syndrome.

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The patient had an uneventful recovery after surgery and received chemotherapy regularly for his liver metastasis.

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MSI testing and further genetic testing are suggested for the patient to identify the suspected Lynch syndrome.

Introduction

While colorectal carcinoma is one of the most commonly diagnosed malignancies, its synchronous occurrence with other primary malignancies is rare.

Presentation of case

In this case, we describe the diagnosis and surgical intervention of a 55-year-old male patient who was found to have colonic adenocarcinoma at the hepatic flexure, right renal urothelial carcinoma, and malignant mesothelioma.

Discussion

None of the previous studies reported these three distinct types of cancer, even in those patients with Lynch Syndrome. To the best of our knowledge, this is the first report of such case. The etiology and pathogenesis of multiple primary malignancies are complex. Common genetic and environmental risk factors that were found in different cancers might increase the risk of multiple primary malignancies.

Conclusion

The use of genetic testing and preoperative imaging studies should be considered to be invaluable tools for detecting synchronous malignancies. Practicing physicians should pay more attention to the risk of simultaneous separate primary malignancies.

Case report: primary acinar cell carcinoma of the liver treated with multimodality therapy

We describe a case of primary acinar cell carcinoma (ACC) originating in the liver in a 54-year-old female, diagnosed following persistent abnormal elevated liver function. Imaging revealed two masses, one dominant lesion in the right hepatic lobe and another in segment IVA. A right hepatectomy was performed to remove the larger lesion, while the mass in segment IVA was unresectable due to its proximity to the left hepatic vein. Immunohistochemical staining showed positivity for trypsin and chymotrypsin. Postoperatively the patient underwent hepatic arterial embolization of the other unresectable lesion followed by FOLFOX chemotherapy. At 20 months from diagnosis the patient is currently under observation with a decreasing necrotic mass and no other disease evident. Based on histology, immunohistochemistry and radiological findings a diagnosis of primary ACC of the liver was made. Genomic assessment of somatic mutations within the patient's tumor was also performed through next generation sequencing and findings were consistent with an acinar malignancy. This case highlights a rare tumor subtype treated with a combination of therapeutic modalities through a multidisciplinary approach.

Pancreatic Cancer in Lynch Syndrome Patients

Although colorectal cancer (CRC) is the most common cancer type in Lynch syndrome (LS) families, patients have also increased lifetime risk of other types of tumors. The accumulated risk of pancreatic cancer (PC) in LS patients is around 3.7% and developed tumors often present a characteristically medullary appearance with prominent lymphocytic infiltration. LS patients are considered in high risk for PC development as they present 8.6-fold increase compared with the general population. Here we review PC cases reported in LS patients and current management guidelines. Literature data show that LS is clearly associated with PC and recent publications also demonstrated a connection with pancreatic neoplasic precursor lesions such as intraductal papillary mucinous neoplasms (IPMN) in these patients. While screening techniques are well established for CRC detection, clear strategies are not yet uniform for PC. Magnetic resonance imaging (MRI) and/or endoscopic ultrasound every 1-2 years in MMR mutation carriers with PC in a first or second-degree relative is recommended. Better pancreatic cancer detection strategies should be urgently defined due to the importance of early diagnosis in this disease.

Pancreatic non-functioning neuroendocrine tumor: a new entity genetically related to Lynch syndrome

Some pancreatic neuroendocrine tumors (P-NETs) are associated with hereditary syndromes. An association between Lynch syndrome (LS) and P-NETs has been suggested, however it has not been confirmed to date. We describe the first case associating LS and P-NETs. Here we report a 65-year-old woman who in the past 20 years presented two colorectal carcinomas (CRC) endometrial carcinoma (EC), infiltrating ductal breast carcinoma, small intestine adenocarcinoma, two non-functioning P-NETs and sebomatricoma. With the exception of one P-NET, all these conditions were associated with LS, as confirmed by immunohistochemistry (IHC) and polymerase chain reaction (PCR). LS is caused by a mutation of a mismatch repair (MMR) gene which leads to a loss of expression of its protein. CRC is the most common tumor, followed by EC. Pancreatic tumors have also been associated with LS. Diagnosis of LS is based on clinical criteria (Amsterdam II and Bethesda) and genetic study (MMR gene mutation). The association between LS and our patient's tumors was confirmed by IHC (loss of expression of proteins MLH1 and its dimer PMS2) and the detection of microsatellite instability (MSI) using PCR.

Update on Lynch syndrome genomics

Four main DNA mismatch repair (MMR) genes have been identified, MLH1, MSH2, MSH6, and PMS2, which when mutated cause susceptibility to Lynch syndrome (LS). LS is one of the most prevalent hereditary cancer syndromes in man and accounts for 1–3 % of unselected colorectal carcinomas and some 15 % of those with microsatellite instability and/or absent MMR protein. The International Society for Gastrointestinal Hereditary Tumours (InSiGHT) maintains a database for LS-associated mutations since 1996. The database was recently reorganized to efficiently gather published and unpublished data and to classify the variants according to a five-tiered scheme linked to clinical recommendations. This review provides an update of germline mutations causing susceptibility to LS based on information available in the InSiGHT database and the latest literature. MMR gene mutation profiles, correlations between genotype and phenotype, and possible mechanisms leading to the characteristic spectrum of tumors in LS are discussed in light of the different functions of MMR proteins, many of which directly serve cancer avoidance.

Triple synchronous primary malignancies: a rare occurrence

Triple synchronous primary malignant neoplasms are rare. The exact aetiology is unknown; however, risk factors include older age, family history, genetic aberrations, prolonged exposure to carcinogens and smoking. We describe a previously healthy 48-year-old woman who presented with abdominal pain and a palpable abdominal mass. Imaging revealed a complex cystic, solid pelvic mass and another mass in the right upper quadrant. She received an extensive abdominal surgery including exploratory laparotomy, pelvic mass resection, total abdominal hysterectomy, bilateral salpingo-oophorectomy, bilateral pelvic lymphadenectomy, omentectomy and right adrenalectomy. During surgery, a mass in the distal sigmoid colon was noted and subsequent sigmoidectomy was performed. The surgical specimen revealed three different primary tumours with three different histologies, a granulosa cell tumour of the ovary, adrenocortical carcinoma and adenocarcinoma of the colon. She received six cycles of adjuvant chemotherapy for colon cancer with 5-fluorourocil, leucovorin and oxaliplatin and is currently living with no recurrence.

Metachronous Uterine Endometrioid Adenocarcinoma and Peritoneal Mesothelioma in Lynch Syndrome: A Case Report

Lynch syndrome is a hereditary disease with germline mutation in a DNA mismatch repair gene, most often presenting with colorectal and/or endometrial carcinomas; however, the spectrum of Lynch syndrome-associated tumors is expanding. In this article, we report a case of a primary peritoneal epithelioid mesothelioma that developed in a Lynch syndrome patient 10 months after diagnosis of uterine endometrioid adenocarcinoma. To our knowledge, this is the first reported case of a Lynch syndrome patient with metachronous uterine endometrioid adenocarcinoma and primary peritoneal mesothelioma.

Nonductal Pancreatic Cancers

Nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms, acinar cell carcinomas, and pancreatoblastomas, are uncommon. These entities share overlapping gross, microscopic, and immunohistochemical features, such as well-demarcated solid neoplasms, monotonous cellular tumor cells with little intervening stroma, and abnormal beta-catenin expression. Each tumor also has unique clinicopathologic characteristics with diverse clinical behavior. To differentiate nonductal pancreatic neoplasms, identification of histologic findings, such as pseudopapillae, acinar cell features, and squamoid corpuscles, is important. Immunostainings for acinar cell or neuroendocrine markers are helpful for differential diagnosis. This article describes the clinicopathologic and immunohistochemical features of nonductal pancreatic cancers.

Impact of DNA mismatch repair system alterations on human fertility and related treatments

DNA mismatch repair (MMR) is one of the biological pathways, which plays a critical role in DNA homeostasis, primarily by repairing base-pair mismatches and insertion/deletion loops that occur during DNA replication. MMR also takes part in other metabolic pathways and regulates cell cycle arrest. Defects in MMR are associated with genomic instability, predisposition to certain types of cancers and resistance to certain therapeutic drugs. Moreover, genetic and epigenetic alterations in the MMR system demonstrate a significant relationship with human fertility and related treatments, which helps us to understand the etiology and susceptibility of human infertility. Alterations in the MMR system may also influence the health of offspring conceived by assisted reproductive technology in humans. However, further studies are needed to explore the specific mechanisms by which the MMR system may affect human infertility. This review addresses the physiological mechanisms of the MMR system and associations between alterations of the MMR system and human fertility and related treatments, and potential effects on the next generation.