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Chetty R. Traditional serrated adenoma (TSA): morphological questions, queries and quandaries. J Clin Pathol 2015; 69:6-11. [PMID: 26553935 DOI: 10.1136/jclinpath-2015-203452] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 10/17/2015] [Indexed: 12/31/2022]
Abstract
AIM Traditional serrated adenoma (TSA) is an uncommon type of serrated adenoma that can be a precursor to biologically aggressive colorectal cancer that invokes the serrated (accelerated) pathway. The purpose of this review is to address some of the more contentious issues around nomenclature, diagnostic criteria, histological variants, coexistence with other polyp types, the occurrence of dysplasia and the differential diagnosis. RESULTS While the vast majority of TSAs are exophytic villiform polyps composed of deeply eosinophilic cells, flat top luminal serrations and numerous ectopic crypt foci, histological variants include flat TSA, filiform TSA and one composed of large numbers of mucin-containing cells. It is unlikely that there is any biological difference between the histological variants. There is a contention that TSAs are not dysplastic ab initio and that the majority do not show cytological atypia. Two types of dysplasia are associated with TSA. Serrated dysplasia is less well recognised and less commonly encountered than adenomatous dysplasia. TSA with dysplasia must be separated from TSA with coexisting conventional adenoma. CONCLUSIONS TSA is a characteristic polyp that may be extremely exophytic, flat or composed of mucin-rich cells and is typified by numerous ectopic crypt foci. They may coexist with other serrated polyps and conventional adenomas. Approximately 20-25% will be accompanied by adenomatous dysplasia.
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Affiliation(s)
- Runjan Chetty
- Laboratory Medicine Program, Department of Pathology, University Health Network and University of Toronto, Toronto, Canada
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52
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Renaud F, Mariette C, Vincent A, Wacrenier A, Maunoury V, Leclerc J, Coppin L, Crépin M, Van Seuningen I, Leteurtre E, Buisine MP. The serrated neoplasia pathway of colorectal tumors: Identification of MUC5AC hypomethylation as an early marker of polyps with malignant potential. Int J Cancer 2015; 138:1472-81. [PMID: 26476272 DOI: 10.1002/ijc.29891] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 10/05/2015] [Indexed: 12/25/2022]
Abstract
The serrated neoplasia pathway accounts for 20-30% of colorectal cancers (CRC), which are characterized by extensive methylation (CpG island methylation phenotype, CIMP), frequent BRAF mutation and high microsatellite instability (MSI). We recently identified MUC5AC mucin gene hypomethylation as a specific marker of MSI CRC. The early identification of preneoplastic lesions among serrated polyps is currently challenging. Here, we performed a detailed pathological and molecular analysis of a large series of colorectal serrated polyps and evaluated the usefulness of mucin genes MUC2 and MUC5AC to differentiate serrated polyps and to identify lesions with malignant potential. A series of 330 colorectal polyps including 218 serrated polyps [42 goblet cell-rich hyperplastic polyps (GCHP), 68 microvesicular hyperplastic polyps (MVHP), 100 sessile serrated adenoma (SSA) and eight traditional serrated adenoma (TSA)] and 112 conventional adenomas was analyzed for BRAF/KRAS mutations, MSI, CIMP, MLH1 and MGMT methylation, and MUC2 and MUC5AC expression and methylation. We show that MUC5AC hypomethylation is an early event in the serrated neoplasia pathway, and specifically detects MVHP and SSA, arguing for a filiation between MVHP, SSA and CIMP-H/MSI CRC, whereas GCHP and TSA arise from a distinct pathway. Moreover, MUC5AC hypomethylation specifically identified serrated lesions with BRAF mutation, CIMP-H or MSI, suggesting that it may be useful to identify serrated neoplasia pathway-related precursor lesions. Our data suggest that MVHP should be recognized among HP and require particular attention.
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Affiliation(s)
- Florence Renaud
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,Pathology Institute, Biology Pathology Center, Lille University Hospital, Lille, France.,North of France Lille 2 University, Lille, France
| | - Christophe Mariette
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Department of Digestive Surgery, Claude Huriez Hospital, Lille University Hospital, Lille, France
| | - Audrey Vincent
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Lille University Hospital, Lille, France
| | - Agnès Wacrenier
- Pathology Institute, Biology Pathology Center, Lille University Hospital, Lille, France
| | - Vincent Maunoury
- Department of Gastroenterology, Claude Huriez Hospital, Lille University Hospital, Lille, France
| | - Julie Leclerc
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Department of Molecular Oncology and Genetics, Biochemistry and Molecular Biology Institute, Biology Pathology Center, Lille University Hospital, Lille, France
| | - Lucie Coppin
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Department of Molecular Oncology and Genetics, Biochemistry and Molecular Biology Institute, Biology Pathology Center, Lille University Hospital, Lille, France
| | - Michel Crépin
- Department of Molecular Oncology and Genetics, Biochemistry and Molecular Biology Institute, Biology Pathology Center, Lille University Hospital, Lille, France
| | - Isabelle Van Seuningen
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Lille University Hospital, Lille, France
| | - Emmanuelle Leteurtre
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,Pathology Institute, Biology Pathology Center, Lille University Hospital, Lille, France.,North of France Lille 2 University, Lille, France
| | - Marie-Pierre Buisine
- Inserm, UMR-S1172, Team 'Mucins, Epithelial Differentiation and Carcinogenesis', Jean-Pierre Aubert Research Center, Lille, France.,North of France Lille 2 University, Lille, France.,Department of Molecular Oncology and Genetics, Biochemistry and Molecular Biology Institute, Biology Pathology Center, Lille University Hospital, Lille, France
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53
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Tsai JH, Cheng CH, Chen CC, Lin YL, Lin LI, Chen ML, Liau JY. Traditional serrated adenoma withBRAFmutation is associated with synchronous/metachronousBRAF-mutated serrated lesions. Histopathology 2015; 68:810-8. [DOI: 10.1111/his.12814] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 08/16/2015] [Indexed: 01/09/2023]
Affiliation(s)
- Jia-Huei Tsai
- Department of Pathology; National Taiwan University; Taipei Taiwan
- Graduate Institute of Pathology; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Chien-Hsuan Cheng
- Department of Internal Medicine; National Taiwan University; Taipei Taiwan
| | - Chien-Chuan Chen
- Department of Internal Medicine; National Taiwan University; Taipei Taiwan
| | - Yu-Lin Lin
- Department of Oncology; National Taiwan University; Taipei Taiwan
- Graduate Institute of Clinical Medicine; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Liang-In Lin
- Department of Laboratory Medicine; National Taiwan University; Taipei Taiwan
- Department of Clinical Laboratory Sciences and Medical Biotechnology; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Mei-Ling Chen
- Department of Pathology; National Taiwan University; Taipei Taiwan
| | - Jau-Yu Liau
- Department of Pathology; National Taiwan University; Taipei Taiwan
- Graduate Institute of Pathology; College of Medicine; National Taiwan University; Taipei Taiwan
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54
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Tsai JH, Liau JY, Lin YL, Tseng LH, Lin LI, Yeh KH, Jeng YM. Frequent BRAF mutation in early-onset colorectal cancer in Taiwan: association with distinct clinicopathological and molecular features and poor clinical outcome. J Clin Pathol 2015; 69:319-25. [PMID: 26500331 DOI: 10.1136/jclinpath-2015-203335] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 09/30/2015] [Indexed: 12/18/2022]
Abstract
BACKGROUND Occurrence of early-onset colorectal cancer (EOCRC) under the age of 30 is very rare and the molecular characteristics are poorly understood. A low BRAF mutation rate has been noted in several studies of EOCRC from Western countries. AIMS To determine the clinicopathological and molecular features of EOCRCs in Taiwan. METHODS KRAS/BRAF gene mutation, mismatch repair protein immunohistochemistry, microsatellite instability and CpG island methylation phenotype analyses were examined to determine the molecular characteristics of EOCRC. RESULTS Sixty-six patients with EOCRC at our hospital between 2000 and 2012 were studied. BRAF mutation was detected in 11 of the 59 tumours analysed (19%) and the rate was significantly higher than the overall BRAF mutation rate of colorectal cancer in patients older than 30 years (p<0.001). Clinically, 9 of 11 patients with BRAF-mutated tumours presented with advanced-stage diseases and they presented significantly more frequently with stage IV disease than those with BRAF wild-type tumours (p=0.042). Histologically, BRAF mutation was associated with a poorly differentiated histology, a serrated precursor polyp and focal signet ring cell differentiation (p=0.042, 0.008 and 0.008, respectively). None of the BRAF-mutated tumours was mismatch repair protein-deficient and/or microsatellite instability-high. Overall survival of patients with BRAF-mutated tumours was significantly worse than that of patients with BRAF wild-type tumours, despite adjustment for the disease stages and tumour differentiation. CONCLUSIONS BRAF mutation was frequent in EOCRCs in Taiwan and was associated with distinct clinicopathological and molecular features.
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Affiliation(s)
- Jia-Huei Tsai
- Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jau-Yu Liau
- Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Lin Lin
- Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Li-Hui Tseng
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Liang-In Lin
- Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kun-Huei Yeh
- Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan Graduate Institute of Oncology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yung-Ming Jeng
- Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei, Taiwan
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55
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Yang HM, Mitchell JM, Sepulveda JL, Sepulveda AR. Molecular and histologic considerations in the assessment of serrated polyps. Arch Pathol Lab Med 2015; 139:730-41. [PMID: 26030242 DOI: 10.5858/arpa.2014-0424-ra] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
UNLABELLED CONTEXT : Colorectal cancer is a heterogeneous disease resulting from different molecular pathways of carcinogenesis. Recent data evaluating the histologic features and molecular basis of the serrated polyp-carcinoma pathway have significantly contributed to more comprehensive classifications of and treatment recommendations for these tumors. OBJECTIVE To integrate the most recent molecular findings in the context of histologic classifications of serrated lesions and their implications in diagnostic pathology and colorectal cancer surveillance. DATA SOURCES Published literature focused on serrated polyps and their association with colorectal cancer. CONCLUSIONS Three types of serrated polyps are currently recognized: hyperplastic polyps, sessile serrated adenomas/polyps, and traditional serrated adenomas. The BRAF V600E mutation is one of the most frequent molecular abnormalities identified in hyperplastic polyps and sessile serrated adenomas. In contrast, in traditional serrated adenomas, either BRAF V600E or KRAS mutations can be frequently identified. CpG methylation has emerged as a critical molecular mechanism in the sessile serrated pathway. CpG methylation of MLH1 often leads to reduced or lost expression in dysplastic foci and carcinomas arising in sessile serrated adenomas/polyps.
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Affiliation(s)
- Hui-Min Yang
- From the Department of Pathology and Cell Biology, Columbia University, New York, New York
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56
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Bettington M, Walker N, Rosty C, Brown I, Clouston A, McKeone D, Pearson SA, Klein K, Leggett B, Whitehall V. Serrated tubulovillous adenoma of the large intestine. Histopathology 2015. [PMID: 26212352 DOI: 10.1111/his.12788] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIMS Most colorectal polyps are classified readily, but a subset of tubulovillous adenomas (TVA) with prominent serrated architecture causes diagnostic confusion. We aimed to (i) identify histological features that separate serrated TVAs from both conventional TVAs and traditional serrated adenomas (TSA) and (ii) perform a clinicopathological and molecular analysis to determine if the serrated TVA has unique features. METHODS AND RESULTS We collected 48 serrated TVAs, 50 conventional TVAs and 66 BRAF wild-type TSAs for analysis. For each polyp we performed a clinicopathological assessment, BRAF and KRAS mutation profiling, cytosine-phosphate-guanosine (CpG) island methylator phenotype status, MGMT methylation and immunohistochemical assessment of seven markers [MutL homologue 1 (MLH1), p16, p53, β-catenin, Ki67, CK7 and CK20]. We found that serrated TVAs can be diagnosed reliably, and have features distinct from both conventional TVAs and TSAs. Compared to conventional TVAs, serrated TVAs are larger, more often proximal, more histologically advanced, show more CpG island methylation and more frequent KRAS mutation. Compared to TSAs they are more often proximal, show less CpG island methylation, more frequent MGMT methylation and more frequent nuclear staining for β-catenin. CONCLUSIONS The serrated TVA can be diagnosed reliably and has unique features. It represents a precursor of KRAS mutated, microsatellite stable colorectal carcinoma.
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Affiliation(s)
- Mark Bettington
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,Envoi Specialist Pathologists, Brisbane, QLD, Australia
| | - Neal Walker
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,Envoi Specialist Pathologists, Brisbane, QLD, Australia
| | - Christophe Rosty
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,Envoi Specialist Pathologists, Brisbane, QLD, Australia.,Genetic Epidemiology Laboratory, Department of Pathology, The University of Melbourne, Carlton, Vic., Australia
| | - Ian Brown
- Envoi Specialist Pathologists, Brisbane, QLD, Australia.,Department of Anatomical Pathology, Pathology Queensland, Brisbane, QLD, Australia
| | - Andrew Clouston
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,Envoi Specialist Pathologists, Brisbane, QLD, Australia.,Department of Anatomical Pathology, Pathology Queensland, Brisbane, QLD, Australia
| | - Diane McKeone
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Sally-Ann Pearson
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Kerenaftali Klein
- Statistics Unit, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Barbara Leggett
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,The Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
| | - Vicki Whitehall
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,School of Medicine, The University of Queensland, Brisbane, QLD, Australia.,Department of Chemical Pathology, Pathology Queensland, Brisbane, QLD, Australia
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57
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Vleugels JLA, IJspeert JEG, Dekker E. Serrated lesions of the colon and rectum: the role of advanced endoscopic imaging. Best Pract Res Clin Gastroenterol 2015; 29:675-86. [PMID: 26381311 DOI: 10.1016/j.bpg.2015.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/20/2015] [Indexed: 02/06/2023]
Abstract
Conventional adenomas were traditionally thought to be the only precursors to colorectal cancer (CRC). Nowadays, also serrated polyps are acknowledged as precursor lesions for CRC, responsible for up to 30% of all CRCs and probably a larger percentage of interval CRCs after colonoscopy. In recent years, much research is being done to unravel the serrated neoplasia pathway. Endoscopic detection of serrated polyps is still a challenge for gastroenterologists, which is illustrated by large variations in detection rates of serrated polyps in the proximal colon. Clinical practice is further inhibited by poor optical differentiation of SSA/Ps from conventional adenomas and HPs and difficult delineation of those lesions, resulting in incomplete resection. The main focus of this review is to highlight recent advancements in endoscopic imaging techniques with regards to detection, differentiation and resection of serrated polyps.
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Affiliation(s)
- J L A Vleugels
- Department of Gastroenterology and Hepatology, Academic Medical Centre, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
| | - J E G IJspeert
- Department of Gastroenterology and Hepatology, Academic Medical Centre, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
| | - E Dekker
- Department of Gastroenterology and Hepatology, Academic Medical Centre, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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58
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Abstract
Colorectal cancer (CRC) is considered a heterogeneous disease, both regarding pathogenesis and clinical behaviour. Four decades ago, the adenoma-carcinoma pathway was presented as the main pathway towards CRC, a conclusion that was largely based on evidence from observational morphological studies. This concept was later substantiated at the genomic level. Over the past decade, evidence has been generated for alternative routes in which CRC might develop, in particular the serrated neoplasia pathway. Providing indisputable evidence for the neoplastic potential of serrated polyps has been difficult. Reasons include the absence of reliable longitudinal observations on individual serrated lesions that progress to cancer, a shortage of available animal models for serrated lesions and challenging culture conditions when generating organoids of serrated lesions for in vitro studies. However, a growing body of circumstantial evidence has been accumulated, which indicates that ≥15% of CRCs might arise through the serrated neoplasia pathway. An even larger amount of post-colonoscopy colorectal carcinomas (carcinomas occurring within the surveillance interval after a complete colonoscopy) have been suggested to originate from serrated polyps. The aim of this Review is to assess the current status of the serrated neoplasia pathway in CRC and highlight clinical implications.
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59
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Bettington ML, Chetty R. Traditional serrated adenoma: an update. Hum Pathol 2015; 46:933-8. [PMID: 26001333 DOI: 10.1016/j.humpath.2015.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/29/2015] [Accepted: 04/03/2015] [Indexed: 02/06/2023]
Abstract
Although recognized 25 years ago, the traditional serrated adenoma (TSA) remains an ongoing source of diagnostic and biologic debate. Recent research has greatly improved our understanding of the morphological and molecular aspects of these polyps. In particular, the recognition of ectopic crypt foci (ECFs) in combination with typical cytology and slitlike serrations improves diagnostic reproducibility. Awareness that many TSAs, particularly BRAF-mutated TSAs, arise in precursor microvesicular hyperplastic polyps and sessile serrated adenomas can aid in making this diagnosis and should not be confused with a sessile serrated adenoma with dysplasia. At a molecular level, TSAs can be divided into 2 groups based on their BRAF or KRAS mutation status. The development of overt cytologic dysplasia is accompanied by TP53 mutation, Wnt pathway activation, and, in some cases, silencing of CDKN2A. Importantly, however, mismatch repair enzyme function is retained. Thus, the TSA is an important precursor of aggressive molecular subtypes of colorectal carcinoma.
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Affiliation(s)
- Mark L Bettington
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, School of Medicine, University of Queensland, Envoi Specialist Pathologists, Brisbane 4072, Queensland, Australia
| | - Runjan Chetty
- Department of Pathology, Laboratory Medicine Program, University Health Network, University of Toronto, Toronto, Ontario M5G 2C4, Canada.
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60
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Bettington ML, Walker NI, Rosty C, Brown IS, Clouston AD, McKeone DM, Pearson SA, Klein K, Leggett BA, Whitehall VLJ. A clinicopathological and molecular analysis of 200 traditional serrated adenomas. Mod Pathol 2015; 28:414-27. [PMID: 25216220 DOI: 10.1038/modpathol.2014.122] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/13/2014] [Accepted: 06/15/2014] [Indexed: 12/12/2022]
Abstract
The traditional serrated adenoma is the least common colorectal serrated polyp. The clinicopathological features and molecular drivers of these polyps require further investigation. We have prospectively collected a cohort of 200 ordinary and advanced traditional serrated adenomas and performed BRAF and KRAS mutational profiling, CpG island methylator phenotype analysis, and immunohistochemistry for a panel of 7 antibodies (MLH1, β-catenin, p53, p16, Ki67, CK7, and CK20) on all cases. The mean age of the patients was 64 years and 50% were female. Of the polyps, 71% were distal. Advanced histology (overt dysplasia or carcinoma) was present in 19% of cases. BRAF mutation was present in 67% and KRAS mutation in 22%. BRAF mutant traditional serrated adenomas were more frequently proximal (39% versus 2%; P≤0.0001), were exclusively associated with a precursor polyp (57% versus 0%; P≤0.0001), and were more frequently CpG island methylator phenotype high (60% versus 16%; P≤0.0001) than KRAS mutant traditional serrated adenomas. Advanced traditional serrated adenomas retained MLH1 expression in 97%, showed strong p53 staining in 55%, and nuclear β-catenin staining in 40%. P16 staining was lost in the advanced areas of 55% of BRAF mutant traditional serrated adenomas compared with 10% of the advanced areas of KRAS mutant or BRAF/KRAS wild-type traditional serrated adenomas. BRAF and KRAS mutant traditional serrated adenomas are morphologically related but biologically disparate polyps with distinctive clinicopathological and molecular features. The overwhelming majority of traditional serrated adenomas retain mismatch repair enzyme function indicating a microsatellite-stable phenotype. Malignant progression occurs via TP53 mutation and Wnt pathway activation regardless of mutation status. However, CDKN2A (encoding the p16 protein) is silenced nearly exclusively in the advanced areas of the BRAF mutant traditional serrated adenomas. Thus, the BRAF mutant traditional serrated adenoma represents an important precursor of the aggressive BRAF mutant, microsatellite-stable subtype of colorectal carcinoma.
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Affiliation(s)
- Mark L Bettington
- 1] The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia [2] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [3] Envoi Specialist Pathologists, Brisbane, QLD, Australia
| | - Neal I Walker
- 1] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [2] Envoi Specialist Pathologists, Brisbane, QLD, Australia
| | - Christophe Rosty
- 1] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [2] Envoi Specialist Pathologists, Brisbane, QLD, Australia [3] Genetic Epidemiology Laboratory, Department of Pathology, The University of Melbourne, Carlton, VIC, Australia
| | - Ian S Brown
- 1] Envoi Specialist Pathologists, Brisbane, QLD, Australia [2] Department of Anatomical Pathology, Pathology Queensland, Brisbane, QLD, Australia
| | - Andrew D Clouston
- 1] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [2] Envoi Specialist Pathologists, Brisbane, QLD, Australia [3] Department of Anatomical Pathology, Pathology Queensland, Brisbane, QLD, Australia
| | - Diane M McKeone
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Sally-Ann Pearson
- The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Kerenaftali Klein
- Statistics Unit, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Barbara A Leggett
- 1] The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia [2] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [3] The Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
| | - Vicki L J Whitehall
- 1] The Conjoint Gastroenterology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia [2] The School of Medicine, The University of Queensland, Brisbane, QLD, Australia [3] Department of Chemical Pathology, Pathology Queensland, Brisbane, QLD, Australia
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61
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Chetty R, Hafezi-Bakhtiari S, Serra S, Colling R, Wang LM. Traditional serrated adenomas (TSAs) admixed with other serrated (so-called precursor) polyps and conventional adenomas: a frequent occurrence. J Clin Pathol 2015; 68:270-3. [PMID: 25589791 DOI: 10.1136/jclinpath-2014-202827] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Traditional serrated adenoma (TSA) is a very characteristic type of serrated polyp that has a predilection for the left colon. Recent molecular advances have shown two molecular phenotypes of TSA: one associated with BRAF mutations and the other with KRAS mutations. The former is associated with hyperplastic polyps (HPs) and sessile serrated adenomas (SSAs), while the latter is associated with more conventional adenomatous dysplasia. AIMS The association of TSAs with so-called precursor lesions (HPs and SSAs) is not well recognised and the purpose of this study was to explore the coexistent presence of HPs, SSAs and adenomatous polyps within a large cohort of TSAs. METHODS In total 149 TSAs were examined for the presence of HP, SSA and adenomatous polyps. RESULTS Seen in 83 men and 65 women ranging in age from 32 to 89 years and 127 were left sided with 22 in the right colon. Seventy-eight of the 149 TSAs showed evidence of another polyp (52.34%): 32 were low-grade tubular/tubulovillous adenomas (TAs/TVAs; 41%), 28 were HPs (36%) and 18 were SSAs (23%). Eleven of the 22 right-sided TSAs were associated with a precursor lesion (1 HP and 7 SSA). In addition, five TSAs showed more than one polyp type: TSA with TA/TVA and HP (3); TSA with TA/TVA and SSA (2). The TAs/TVAs were adjacent to the TSA but occurred as a separate discrete polyp, while HPs and SSAs were intermingled with the TSA and present at the base and surface of the lesion. CONCLUSIONS More than 50% of TSAs are associated with a precursor lesion or adjacent TA/TVA. Their recognition is important as this may have surveillance and management ramifications.
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Affiliation(s)
- Runjan Chetty
- Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada
| | - Sara Hafezi-Bakhtiari
- Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada
| | - Stefano Serra
- Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada
| | - Richard Colling
- Department of Cellular Pathology, Oxford University Hospitals, Oxford, UK
| | - Lai Mun Wang
- Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada
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62
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Abstract
The serrated pathway (SP) can be viewed as two parallel, but partially overlapping, arrays of colorectal precursor lesions, and their respective endpoint carcinomas, that are distinct from those of the conventional adenoma-carcinoma sequence (APC-pathway). In this review we focus at the outset on the clinical impact, pathological features, molecular genetics and biological behaviours of the various SP cancers. Then we summarize the clinicopathological features, classification and molecular profiles of the two main precursor lesions that anchor the respective pathways: (i) sessile serrated adenoma/polyp (SSA/P), also called sessile serrated lesion (SSL), and (ii) traditional serrated adenoma (TSA). Activating mutations of the RAS-RAF-MAPK pathway initiate and sustain the lesions of the SP, and CpG island methylation of the promoter regions of tumour suppressor and DNA repair genes play the major role in their neoplastic progression. The SP includes microsatellite stable (MSS) carcinomas that are among the most biologically aggressive colorectal carcinomas (CRC), and also accounts for the great preponderance of sporadic hypermutated, mismatch repair (MMR)-deficient or microsatellite instable (MSI) CRC. The identification, removal and appropriate classification of at-risk SP precursors and surveillance of individuals who harbour these lesions present a challenge and opportunity for CRC prevention and mortality reduction.
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Affiliation(s)
- Michael J O'Brien
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA
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