Clinical significance of type VI pit pattern subclassification in determining the depth of invasion of colorectal neoplasms

AIM: To clarify whether subclassification of the type V I pit pattern on the basis of magnifying colonoscopy findings is useful in determining the type and depth of invasion of colorectal neoplasms. METHODS: We retrospectively analyzed 272 colorectal neoplasms (117 dysplasias and 155 submucosal invasive carcinomas; 228 patients) with a type V pit pattern (type VI, n = 202; type VN, n = 70 (Kudo and Tsuruta classification system)). We divided lesions with a type VI pit pattern into two subclasses, mildly irregular lesions and severely irregular lesions, according to the prominent and detailed magnifying colonoscopy findings. We examined the relation between these two subclasses and histology/invasion depth. RESULTS: One hundred and four lesions (51.5%) were judged to be mildly irregular, and 98 lesions (48.5%) were judged to be severely irregular. Ninety-seven (93.3%) mildly irregular lesions showed dysplasias or submucosal invasion of less than 1000 µm (SM < 1000 µm). Fifty-five (56.1%) severely irregular lesions showed submucosal invasion equal to or deeper than 1000 µm (SM ≥ 1000 µm). Mild irregularity was found significantly more often in dysplasias or lesions with SM < 1000 µm than in lesions with SM ≥ 1000 µm (P < 0.01).