Diagnosis of invasion depth in early colorectal carcinoma by pit pattern analysis with magnifying endoscopy

Background: The aim of this study was to clarify whether various pit patterns on the surface of colorectal tumors are associated with various levels of submucosal invasion. Methods: We examined pathologic features of the pit pattern of the tumor surface in 457 colorectal adenomas and early carcinomas. The examinations involved the use of magnifying endoscopy with indigocarmine dye spraying or crystal violet staining methods. Regarding the pit pattern classification, we used the types I, II, III L , III S , IV, V A and V N . We subclassified the V N pit pattern according to the area of the tumor surface covered into grades A (small), B (medium) and C (large). Results: Magnifying colonoscopic observation revealed the rates of submucosal invasion associated with specific pit patterns to be 1% (3/213) for III L , 5% (2/42) for III S , 8% (4/57) for IV, 14% (13/93) for V A and 80% (42/52) for V N . The rates of submucosal massive invasion (> 400 μm) associated with specific pit patterns was 0% (0/213) for III L , 0% (0/42) for III S , 4% (2/57) for IV, 5% (5/93) for V A and 72% (38/52) for V N . Within the V N pit pattern subclassification, the incidence of submucosal invasion ≥ 1500 μm was found each grade (A, B & C): 5% (1/19) for grade A, 64% (14/22) for grade B and 93% (13/14) for grade C. Conclusion: Determination of pit pattern is useful for prediction of submucosal invasion depth and for decisions concerning treatment in colorectal tumors. Lesions with V A and non‐grade C V N pit patterns are candidates for total endoscopic resection. A grade C V N pit pattern is a definite indicator of severely invasive submucosal carcinoma, which is unresectable by endoscopic resection.