Evaluation of new subclassification of type V-I pit pattern for determining the depth and type of invasion of colorectal neoplasm

Background Colorectal neoplasms with a type V-I pit pattern include various lesions, such as adenomas, intra-mucosal cancers, and submucosal carcinomas. Methods We analyzed 96 colorectal neoplasms with a type V-I pit pattern and identified six different variants: ( 1) unclear outline of the pit; (2) irregular margins of the pit; (3) narrowing of the pit; (4) ragged array of the pit; (5) high residual density of the pit; (6) abnormal branching of the pit. We examined the relationship between the appearance of each V-I pit pattern and histology, including the depth of invasion. Results In univariate logistic regression analysis the unclear outline, irregular margins, and narrowing of the pit were significantly associated with a submucosal (SM) invasion >= 1000 mu m (P < 0.01). In multivariate logistic regression analysis, unclear outline of the pit was shown to be the only significant predictor of highly invasive submucosal cancer (odds ratio = 24.20, P < 0.0001). Regarding tumor morphology, the following were significantly associated with an SM invasion >= 1000 mu m: in protruded type, ragged array (P = 0.022), irregular margins of the pit (P = 0.011), and unclear outline of the pit (P < 0.01); in flat type, irregular margins of the pit (P < 0.01) and unclear outline of the pit (P < 0.01); and in the depressed type, narrowing of the pit (P = 0.015) and unclear outline of the pit (P < 0.01). Conclusions Subclassification of the type V-I pit pattern is useful for determining the depth of invasion of colorectal neoplasms.