title: Traditional serrated adenomas (TSAs) admixed with other serrated (so-called precursor) polyps and conventional adenomas: a frequent occurrence.
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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Runjan
authors.initials: R
authors.lastname: Chetty
authors.affiliation: Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Hafezi-Bakhtiari
authors.affiliation: Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Stefano
authors.initials: S
authors.lastname: Serra
authors.affiliation: Department of Cellular Pathology, Oxford University Hospitals, Oxford, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Colling
authors.affiliation: Department of Pathology, Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Lai Mun
authors.initials: LM
authors.lastname: Wang
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000473:pathology*; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009864:Ontario / Q000453:epidemiology; D011230:Precancerous Conditions / Q000453:epidemiology / Q000473:pathology*
keywords: COLON; GASTROINTESTINAL DISEASE; GUT PATHOLOGY