P0015 PP BETA CATENIN IMMUNOHISTOCHEMISTRY IN SYNDROMIC COMPARED TO SPORADIC JUVENILE POLYPS

Abstract

Introduction: Juvenile Polyps (JP) are usually sporadic; typically isolated and entail no increased risk of colorectal cancer (CRC). Juvenile Polyposis Syndrome (JPS) is rare (1 in 15,000), usually familial, characterized by numerous (>5) JP and a heightened risk of CRC. Multiple juvenile polyps are common, and differentiation between syndromic and sporadic subtypes impacts endoscopic surveillance. Beta catenin is an intracellular structural protein that is also involved in transcription activation in neoplastic transformation. Aims: to compare beta catenin expression and intracellular distribution within syndromic and sporadic JP. Methods: Quantitative beta catenin expression and intracellular distribution was studied by immunohistochemistry. We compared 41 polyps from 7 patients (4M) with Juvenile Polyposis Syndrome with 17 polyps from 17 patients (11M) with isolated juvenile polyps, a negative family history of hereditary polyposis syndrome, and no history of recurrence based on questionnaire or repeat endoscopy at 5–10 years following initial presentation. Beta catenin staining was classified as nuclear stippling, cytoplasmic localization and intensity of staining. Results: Basal cytoplasmic localization of beta catenin was observed more frequently in sporadic than syndromic polyps (31 vs 17%) and nuclear stippling pattern was reported more often with syndromic polyps (87 vs 75% NS). Although the intensity of cytoplasmic staining was almost identical, 2 syndromic polyps exhibited markedly increased cytoplasmic staining. Conclusion: Our findings do not support the use of beta catenin immunohistochemistry in differentiating between syndromic and sporadic JP: indeed beta catenin over-expression and nuclear translocation may have a role in the growth of a subset of JPS associated polyps; this phenotypic diversity may be related to the genetic heterogeneity of JPS.