Sa1909 GRADING OF DYSPLASIA FOR DIAGNOSING COLORECTAL ADENOMAS USING ENDOCYTOSCOPY

Abstract

Recent opinions have expressed that if an endoscopic diagnosis of adenomas can be made with high accuracy, then, the omission of a pathological diagnosis following endoscopic resection is acceptable. Currently, there is no clear consensus regarding whether endoscopic treatment is required for all adenomas. Colonoscopy-based grading of dysplasia can be clinically effective for diagnosing adenomas, if such a diagnosis of adenomas, particularly of low-grade adenomas, can be made with high accuracy. In this study, we focused on the existence of mixed-pit pattern type I lesions in slit-like lumens, which is an endocytoscopy (EC) finding characteristic of adenomas, and investigated pathological findings that were correlated with this observation. We retrospectively examined 724 lesions among the neoplastic lesions that could be observed by EC between May 2005 and May 2017 and that were classified as EC2 according to the EC classification system and could be pathologically examined via endoscopic resection. Lesions characterized by mixed-pit pattern type I in slit-like lumens were classified as EC2 normal pit (NP) sign (+), while those characterized by slit-like lumens only were classified as EC2 NP sign (−). We investigated the final pathological diagnosis results, and also examined the location, diameter, and morphological type of NP (+) lesions to elucidate their clinical traits. A total of 466 lesions were classified as EC2 NP sign (+). Of these, low-grade adenomas accounted for 450 lesions and advanced lesions (high-grade dysplasia, tubulovillous adenoma, invasive cancer) accounted for 16. NP sign (+) as an indicator of low-grade adenomas had a sensitivity of 85.4%, specificity of 90.8%, positive predictive value of 96.6%, negative predictive value of 67.1%, accuracy of 86.7%, and positive likelihood ratio of 9.23. Furthermore, an examination of the EC2 NP (+) rate by location, diameter, and morphological type of the lesions revealed that 56.6% of the lesions were located in the distal colon and 75.7% were located in the proximal colon; 81.4% of the lesions were ≤10 mm in diameter and 10.9% were ≥10 mm. Further, 53.9% of the lesions were of the protruding morphological type and 79.8% were of the flat/depressed type. Taken together, this indicated that the EC2 NP sign (+) rate was significantly higher in lesions located in the proximal colon (p < 0.001), that were ≤10 mm in diameter (p < 0.001), and that were of the flat/depressed type (p < 0.001). These results suggest that when using EC for diagnosing colorectal neoplastic lesions, NP sign is a good indicator of low-grade adenomas with the EC2 classification. Furthermore, the NP (+) rate tended to be high in lesions located in the proximal colon, that were ≤10 mm in diameter, and that were of the flat/depressed type.