[603] The Variants of Gastric Epithelial Dysplasia Display Different Biologic Characteristics: An Immunohistochemical Study of p53, Ki-67, beta Catenin and Smad4 Expression

HJ Kang, JH Lee, GH Kim, GY Lauwers, DH Shin, KU Choi, CH Lee, GY Huh, MY Sol, DY Park. Pusan National University Hospital, Busan, Korea; Massachusetts General Hospital, Boston, MA

Background: Gastric epithelial dysplasia (GED) can be morphologically categorized into 2 types:adenomatous (or intestinal) and foveolar (or gastric / type II). While no distinct genetic differences have been demonstrated between these subtypes thus far, the immunophenotypic expression of p53, Ki-67, beta-catenin and Smad4 has not been simultaneously evaluated in this context previously.
Design: 58 cases of GED were immunohistochemically evaluated for expression of p53, Ki-67, beta-catenin and Smad4 and the findings were correlated with the morphologic subtypes. Accordingly, GED was classified as adenomatous, foveolar, or hybrid (showing features of both types), based on routine histologic evaluation.
Results: An adenomatous morphology was diagnosed in 26/58 cases (44.8%), hybrid in 18/58 cases (31.0%) and a foveolar subtype was observed in 14/58 cases (24.2%). The expression of the biologic immunomarkers was different between both dysplastic variants: the foveolar and hybrid types when analyzed as a group showed more p53 expression (p=0.012) and higher Ki-67 proliferation index (p=0.006) when compared to the adenomatous type. Conversely, nuclear beta-catenin expression was more common in adenomatous type (10/16, 62.5%) than foveolar (2/14, 14.3%), hybrid type (5/18, 27.7%), but it was statistically insignificant (p=0.168). There was no difference of Smad4 expression among three types of GED.
Conclusions: The various expression of p53 and Ki-67 suggests biologic differences between the in three epithelial phenotypes of GED: intestinal, gastric/foveolar, and hybrid type. The clinical significance of these differences needs to be investigated in future studies.
Category: Gastrointestinal

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 100, Tuesday Afternoon