Abstract
We examined the association between irregular pit patterns and the complex tubular structures of colorectal tumors. A total of 244 resected colorectal epithelial tumors with type V pit patterns of Kudo's classification on magnifying endoscopy were studied. The tumors were confined to the lamina propria mucosae or submucosa. We histopathologically examined specimens and the tubular irregularity of in each lesion was graded into 5 grades (G0 to G4). The mean grades of tubular irregularity were compared between lesions with a type VI pit pattern, showing an irregular surface and those with a type VN pit pattern, showing a nonstructured surface; the depth of tumor invasion was also considered. The grades of tubular irregularity were as follows: G0, no fusionated structures; G1, fusionated structures localized at the base of tubules; G2, fusionated structures extending to the tumor surface; G3, fusionated structures occupying the entire tubules, and G4, interstitial tissue exposed on the tumor surface, creating a nonstructured appearance. The mean grade of tubular irregularity was higher in lesions with a type VN pit pattern than in those with a type VI pit pattern. Among lesions with a type VI pit pattern, the mean grade of tubular irregularity tended to be higher in lesions with deeper invasion and was significantly higher in lesions with massive submucosal invasion than in those with slight submucosal invasion. An irregular pit pattern of G3 may be an indicator of massive submucosal invasion. The appearance of irregular pit patterns was closely linked to increasing complexity of tubules in colorectal tumors.
