To investigate the usefulness of pit pattern to estimate depth of submucosal invasion and the mechanism of change in pit pattern by tumor character in colorectal cancer, we investigated the relation between pit pattern and immuno-histochemical E-cadherin and β-catenin expression. Fifty-seven colorectal tumors including 37 submucosal invasive carcinomas, 10 high-grade adenomas and 10 cases of advanced carcinomas invading into the muscularis propria were divided into a non-VN and VN group according to a modification of the Kudo classification system. In addition, distance between the invasive front and muscularis mucosae was measured, and histological and immunohistochemical expression of E-cadherin and β-catenin in the superficial portion and invasive portion were examined. Many tumors with deep invasion were classified in the VN group. Among the submucosal invasive carcinomas in the VN group, there was a significantly higher number with deep invasion than with slight invasion. All submucosal invasive cancers with lymphatic invasion also had deep submucosal invasion. Immunohistochemical analysis revealed significant loss of normal membrano-cytoplasmic β-catenin expression in the superficial area of cancers in the VN group. Submucosal carcinoma with deep invasion also had significant loss of membrano-cytoplasmic expression of β-catenin in the superficial area. Pit pattern is useful not only to predict tumor character but also to estimate depth of invasion. Change in pit pattern may be associated with abnormality of β-catenin expression.

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