Evaluation of the extended Japan NBI expert team classification of subtype 2B in laterally spreading colorectal tumors based on blue laser imaging

Objectives The Japan NBI Expert Team ( JNET ) classification has good diagnostic potential for colorectal diseases. We aimed to explore the diagnostic value of the JNET classification type 2B (JNET2B) criteria for colorectal laterally spreading tumors (LSTs) based on magnifying endoscopy with blue laser imaging (ME‐BLI) examination. Methods Between January 2017 and June 2023, 218 patients who were diagnosed as having JNET2B‐type LSTs using ME‐BLI were included retrospectively. Endoscopic images were reinterpreted to categorize the LSTs as JNET2B‐low (n = 178) and JNET2B‐high (n = 53) LSTs. The JNET2B‐low and JNET2B‐high LSTs were compared based on their histopathological and morphological classifications. Results Among the 178 JNET2B‐low LSTs, 86 (48.3%) were histopathologically classified as low‐grade intraepithelial neoplasia, 54 (30.3%) as high‐grade intraepithelial neoplasia (HGIN), 37 (20.8%) as intramucosal carcinoma (IMC), and one (0.6%) as superficial invasive submucosal carcinoma (SMC1). Among the 53 JNET2B‐high LSTs, five (9.4%) were classified as HGIN, 28 (52.9%) as IMC, 15 (28.3%) as SMC1, and 5 (9.4%) as deep invasive submucosal carcinoma. There were significant differences in this histopathological classification between the two groups ( P < 0.001). However, there was no significant difference between JNET2B‐low and JNET2B‐high LSTs based on their morphological classification (granular vs nongranular) or size (<20 mm vs ≥20 mm). Besides, the κ value for JNET2B subtyping was 0.698 (95% confidence interval 0.592–0.804) between the two endoscopists who reassessed the endoscopic images. Conclusion The JNET2B subtyping of LSTs has a diagnostic potential in the preoperative setting, and may be valuable for treatment decision‐making.