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serrated colorectal polyp; serrated adenoma

- distinct from adenomas (adenomatous polyps) Classification: - includes a) sessile serrated adenomas 1] sessile or flat 2] distributed toward the proximal colon 3] endoscopically subtle 4] some share molecular features with a group of colon cancers that account for many cancers that develop after colonoscopy a] the BRAF mutation b] the CpG island methylator phenotype c] microsatellite instability b) traditional serrated adenomas - infrequent, dysplastic, often protuberant or pedunculated, located toward the distal colon Etiology: - serrated polyposis syndrome Pathology: 1) large serrated polyps may be associated with colorectal cancer a) associated with DNA mismatch repair deficiency & microsatellite instability b) associated with BRAF mutations (78%) or K-ras mutations (11%) c) benign hyperplastic polyps tend to have more K-ras mutations than BRAF mutations d) MLH1 promoter methylation is frequent e) associated with smoking & estrogen withdrawal [3] r) these colon cancers tend to occur on the right side of the colon 2) no increased risk of proximal colon cancer with distal (rectosigmoid) hyperplastic polyps [2] * pathologic distinction between hyperplastic polyps sessile serrated adenomas is not reliable in clinical practice & can be difficult, even for experts [4,6] Management: - follow-up colonoscopy in 3 years for - serrated polyps >= 10 mm - dysplastic serrated polyps - traditional serrated adenomas - follow-up colonoscopy in 5 years for - serrated polyps < 10 mm - see notes Notes: - pathologic distinction between hyperplastic polyps sessile serrated adenomas is not reliable in clinical practice & can be difficult, even for experts [4,6]

Related

serrated polyposis syndrome; hyperplastic polyposis syndrome

General

colorectal polyp

References

  1. Journal Watch 21(19):151, 2001 Hawkins & Ward J Natl Cancer Inst 93:1307, 2001
  2. Lin OS, Schembre DB, McCormick SE, Gluck M, Patterson DJ, Jiranek GC, Soon MS, Kozarek RA. Risk of proximal colorectal neoplasia among asymptomatic patients with distal hyperplastic polyps. Am J Med. 2005 Oct;118(10):1113-9. PMID: 16194642
  3. Pathology Outlines Colon tumor, Polyps, Adenoma-carcinoma sequence of colon http://www.pathologyoutlines.com/topic/colontumoradenomacarcinoma.html
  4. Schreiner MA et al. Proximal and large hyperplastic and nondysplastic serrated polyps detected by colonoscopy are associated with neoplasia. Gastroenterology 2010 Nov; 139:1497. PMID: 20633561 - Hiraoka S et al. The presence of large serrated polyps increases risk for colorectal cancer. Gastroenterology 2010 Nov; 139:1503, 1510. - Terdiman JP and McQuaid KR. Surveillance guidelines should be updated to recognize the importance of serrated polyps. Gastroenterology 2010 Nov; 139:1444. PMID: 20875785
  5. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015
  6. Hetzel JT, Huang CS, Coukos JA et al Variation in the detection of serrated polyps in an average risk colorectal cancer screening cohort. Am J Gastroenterol. 2010 Dec;105(12):2656-64 PMID: 20717107
  7. Rex DK, Ahnen DJ, Baron JA et al Serrated lesions of the colorectum: review and recommendations from an expert panel. Am J Gastroenterol. 2012 Sep;107(9):1315-29 PMID: 22710576