Sessile Serrated Adenoma (SSA) vs. Traditional Serrated Adenoma (TSA)
- 1 January 2008
- journal article
- Published by Ovid Technologies (Wolters Kluwer Health) in The American Journal of Surgical Pathology
- Vol. 32 (1), 21-29
- https://doi.org/10.1097/pas.0b013e318157f002
Abstract
The morphologic distinction between various serrated polyps of the colorectum may be challenging. The distinction between sessile serrated adenoma (SSA) and traditional serrated adenoma (TSA) may be difficult using currently available criteria mostly based on cytologic characteristics. We have evaluated 66 serrated polyps including 29 SSA, 18 TSA, and 19 hyperplastic polyps for overall shape of the polyps, architectural features of individual crypts, the presence of eosinophilic cytoplasm, size and distribution of the proliferation and maturation zones, as well as Ki-67 and CK20 expression. The extent of the expression of CK20 and Ki-67 could not distinguish between the 3 types of serrated polyps, but the distribution of their expression was very helpful and differences were statistically significant. The distribution of Ki-67+ cells was the single most helpful distinguishing feature of the serrated polyp type (P<0.0001, chi test). Hyperplastic polyps had regular, symmetric, and increased Ki-67 expression. SSA had irregular, asymmetric, and highly variable expression of Ki-67. TSA had low Ki-67 expression, which was limited to "ectopic crypts" and admixed tubular adenomalike areas. In serrated polyps, ectopic crypt formation (ECF) defined by the presence of ectopic crypts with their bases not seated adjacent to the muscularis mucosae was nearly exclusive to TSA and was found in all cases, while the presence of cytologic atypia and eosinophilia of the cytoplasm were characteristic, but not limited to TSA. No evidence of ECF, but nevertheless abnormal distribution of proliferation zone was characteristic of SSA, whereas HP had neither. The presence of the ECF defines TSA in a more rigorous fashion than previous diagnostic criteria and also explains the biologic basis of exuberant protuberant growth associated with TSA and the lack of such growth in SSA. Recognition of this phenomenon may also help in exploring the genetic and molecular basis for differences between SSA and TSA, because these architectural abnormalities may well be a reflection of abnormalities in genetically programmed mucosal development.Keywords
This publication has 41 references indexed in Scilit:
- Molecular classification and genetic pathways in hyperplastic polyposis syndromeThe Journal of Pathology, 2007
- Crypt dynamics and colorectal cancer: advances in mathematical modellingCell Proliferation, 2006
- MIB-1 and MCM-2 Immunohistochemical Analysis Does Not Aid in Identification of Serrated Colorectal Polyps With Abnormal ProliferationAmerican Journal of Clinical Pathology, 2006
- Small Colonic Microsatellite Unstable Adenocarcinomas and High-Grade Epithelial Dysplasias in Sessile Serrated Adenoma Polypectomy SpecimensAmerican Journal of Clinical Pathology, 2006
- Isolated crypts form spheres prior to full intestinal differentiation when grown as xenografts: anin vivo model for the study of intestinal differentiation and crypt neogenesis, and for the abnormal crypt architecture of juvenile polyposis coliThe Journal of Pathology, 2005
- β-Catenin and TCF Mediate Cell Positioning in the Intestinal Epithelium by Controlling the Expression of EphB/EphrinBCell, 2002
- The β-Catenin/TCF-4 Complex Imposes a Crypt Progenitor Phenotype on Colorectal Cancer CellsCell, 2002
- RAF/RAS oncogenes and mismatch-repair statusNature, 2002
- Three-dimensional Reconstruction and Fractal Geometric Analysis of Serrated AdenomaJapanese Journal of Cancer Research, 2002
- Integrins and anoikisCurrent Opinion in Cell Biology, 1997