title: Hyperplastic polyp? Look again... the impact of the new classification for serrated polyps.
abstract: BACKGROUND
  The World Health Organization reviewed the classification for serrated colonic polyps in 2010. A new entity, sessile serrated adenoma, was included with two variants: with and without cytological dysplasia. This lesion's malignant potential has been recognized and according to the new classification, many polyps may be reclassified. The impact of this change is yet to be assessed.
  
  
  OBJECTIVE
  Analyze the proportion of lesions that were reclassified according to the new World Health Organization classification and the variables that influenced it.
  
  
  METHODS
  Every patient with at least one sessile serrated adenoma diagnosed in a 5 year period was included. All polyps (regardless of type) resected during the study period were reviewed. Data concerning polyp's characteristics and patient variables were collected. Forty consecutive patients were included [13 female, mean age at 1st sessile serrated adenoma -59 yrs (34-80)].
  
  
  RESULTS
  Were reviewed 247 polyps: hyperplastic--42%; conventional adenomas--29%; sessile serrated adenoma--24%; serrated adenomas--5%. Sixty-three polyps were reclassified: 43 hyperplastic, 12 serrated adenomas, 7 sessile serrated adenoma and 1 conventional adenoma with low grade dysplasia. Reclassification was significantly greater for hyperplastic polyps when compared with the other subtypes. Forty-three of one hundred and four (41%) hyperplastic polyps were reclassified all as sessile serrated adenoma. In these polyps the probability of reclassification was independent from polyp location but was greater if polyp size ≥ 5 mm.
  
  
  CONCLUSIONS
  This is a single center, rectrospective study. The fact that it was done in an Oncology Referral Institution with a Family Risk Clinic may have influenced the results. Nevertheless the impressive reclassification rate for Hyperplastic Polyps and the fact that they were reclassified mainly as Serrated Adenomas makes these results relevant to daily practice.
  
  
  CONCLUSIONS
  Our results suggest that, according to the new World Health Organization classification for serrated colonic polyps, a considerable proportion of hyperplastic polyps will be reclassified. The serrated pathway of colorectal carcinogenesis has probably been underestimated and at-risk patients may have been under inappropriate surveillance.
authors.affiliation: Serviço de Gastrenterologia. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Fidalgo
authors.affiliation: Serviço de Anatomia Patológica. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Liliana
authors.initials: L
authors.lastname: Santos
authors.affiliation: Serviço de Gastrenterologia. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal. Clínica de Risco Familiar. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Isadora
authors.initials: I
authors.lastname: Rosa
authors.affiliation: Serviço de Anatomia Patológica. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Fonseca
authors.affiliation: Serviço de Gastrenterologia. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal. Clínica de Risco Familiar. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Lage
authors.affiliation: Serviço de Gastrenterologia. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal. Clínica de Risco Familiar. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Claro
authors.affiliation: Serviço de Anatomia Patológica. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Chaves
authors.affiliation: Serviço de Gastrenterologia. Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. Lisboa. Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Dias Pereira
mesh_terms: D000236:Adenoma / Q000145:classification* / Q000473:pathology*; D000328:Adult; D003110:Colonic Neoplasms / Q000145:classification* / Q000473:pathology*; D003111:Colonic Polyps / Q000145:classification* / Q000473:pathology*; D005260:Female; D006801:Humans; D006965:Hyperplasia; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014944:World Health Organization