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Prevalence of MLH1 and MSH2 mutations in colorectal serrated polyps and its morphological and cytoarchitectural correlation

Abstract:

Introduction: Serrated polyps of the large intestine comprise a diverse group of lesions of the colonic mucosa that includes hyperplastic polyps, sessile serrated adenomas and traditional serrated adenomas. These lesions have been considered precursors of colorectal carcinogenesis associated with microsatellite instability. Objective: To determine the prevalence of the MLH1 y MSH2 mutations in serrated polyps and to correlate with morphological and cytoarchitectural characteristics. Methods: A descriptive study of 164 serrated colorectal polyps was performed. Tissue microarray technique was used to analyze their morphological and cytoarchitectural features and immunohistochemical expression of the MLH1 and MSH2 mutated genes in different regions of the colonic crypts. Results: One-hundred and fifty-nine hyperplastic polyps, 2 sessile serrated adenomas and 3 traditional serrated adenomas were included. There was no significant difference in the immunohistochemical expression between hyperplastic polyps and serrated adenomas for MLH1 and MSH2. Moreover, the degree of expression decreased from the base toward the surface of the crypt where it was negative. This finding was not a sufficient to qualify for microsatellite instability. Conclusions: The prevalence of the MLH1 and MSH2 mutated genes were similar between hyperplastic polyps and serrated adenomas. No correlation was found with morphological and cytoarchitectural characteristics. © 2011 Asociación Mexicana de Gastroenterología.