title: Critical appraisal of the diagnosis of the sessile serrated adenoma.
abstract: The sessile serrated adenoma (SSA) is a relatively recently described polyp that can present diagnostic difficulties for the practicing pathologist. The frequency of SSA diagnoses varies dramatically in the reported literature. In addition, the histologic interface between the microvesicular hyperplastic polyp (MVHP) and the SSA continues to be a diagnostic problem. The trend in recent years has been toward a lower threshold for SSA diagnosis. Herein, we have performed a cross-sectional study of 6340 colorectal polyps received at a high-volume community-based pathology practice over a 3-month period. After central review, with strict application of the diagnostic criteria outlined in the 2010 edition of the World Health Organization Classification of Tumours of the Digestive Tract, we found that SSAs represented 12.1% of all polyps. In addition, we developed novel diagnostic subcategories in an attempt to determine the most appropriate cutoff for the interface between the MVHP and the SSA. We found that serrated polyps (MVHPs or SSAs) with any SSA-like crypts had clinical features more in common with the SSA than the MVHP and that this diagnostic cutoff showed good reproducibility between pathologists. This supports the position of a recent consensus publication proposing that polyps with as few as 1 SSA-type crypt should be diagnosed as an SSA. Applying these criteria to our cohort yields an overall SSA rate of 14.7%. In summary, we believe that SSAs continue to be underdiagnosed in pathologic practice and that this may result in inadequate surveillance and thus contribute to interval colorectal carcinomas.
authors.affiliation: *The Conjoint Gastroenterology Laboratory §Cancer and Population Studies Group ¶The Statistics Unit, QIMR Berghofer Medical Research Institute †School of Medicine, The University of Queensland ‡Envoi Specialist Pathologists Departments of ∥Anatomical Pathology #Chemical Pathology, Central Laboratory, Pathology Queensland **The Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Bettington
authors.forename: Neal
authors.initials: N
authors.lastname: Walker
authors.forename: Christophe
authors.initials: C
authors.lastname: Rosty
authors.forename: Ian
authors.initials: I
authors.lastname: Brown
authors.forename: Andrew
authors.initials: A
authors.lastname: Clouston
authors.forename: Leesa
authors.initials: L
authors.lastname: Wockner
authors.forename: Vicki
authors.initials: V
authors.lastname: Whitehall
authors.forename: Barbara
authors.initials: B
authors.lastname: Leggett
mesh_terms: D000236:Adenoma / Q000145:classification / Q000473:pathology*; D000368:Aged; D016009:Chi-Square Distribution; D016000:Cluster Analysis; D003111:Colonic Polyps / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000145:classification / Q000473:pathology*; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011793:Queensland; D015203:Reproducibility of Results