gathered ME-NBI images and patients' clinical information. Kato Y provided valuable advice regarding the technical information and managed the AI-assisted CNN-CAD system and analyzed the data in this manuscript. All authors gave final approval for publication. Ueyama H, Nagahara A, and Tada T take full responsibility for the work as a whole, including the study design, access to data, and the decision to submit and publish the manuscript.

BackgroundColorectal sessile serrated adenoma/polyps (SSA/Ps) are considered early precursor lesions in the serrated neoplasia pathway. Recent studies have shown associations of SSA/Ps with lost MLH1 expression, a CpG island methylator phenotype, and BRAF mutations. However, the molecular biological features of SSA/Ps with early neoplastic progression have not yet been fully elucidated, owing to the rarity of cases of SSA/P with advanced histology such as cytologic dysplasia or invasive carcinoma. In this study, we aimed to elucidate the molecular biological features of SSA/Ps with dysplasia/carcinoma, representing relatively early stages of the serrated neoplasia pathway.MethodsWe performed immunostaining for β-catenin, MLH1, and mucins (e.g., MUC2, MUC5AC, MUC6, and CD10); targeted next-generation sequencing; and microsatellite instability (MSI) testing in 8 SSA/P lesions comprised of 4 SSA/Ps with high-grade dysplasia and 4 SSA/Ps with submucosal carcinoma.ResultsLost MLH1 expression was found in 5 cases. All lesions studied were positive for nuclear β-catenin expression. Regarding phenotypic mucin expression, all lesions were positive for MUC2, but negative for CD10. MUC5AC and MUC6 positivity was observed in 7 cases. Genetically, the most frequently mutated gene was BRAF (7 cases), and other mutations were detected in FBXW7 (3 cases); TP53 (2 cases), and KIT, PTEN, SMAD4, and SMARCB1 (1 case each). Furthermore, 4 of 8 lesions were MSI-high and the remaining 4 lesions were microsatellite-stable (MSS). Interestingly, all 4 MSI-high lesions displayed MLH1 loss, 3 of which harbored a FBXW7 mutation, but not a TP53 mutation. However, 2 MSS lesions harbored a TP53 mutation, although none harbored a FBXW7 mutation.ConclusionsSSA/Ps with dysplasia/carcinoma frequently harbored BRAF mutations. Activation of the WNT/β-catenin signaling pathway may facilitate the development of dysplasia in SSA/Ps and progression to carcinoma. Furthermore, our results suggested that these lesions might be associated with both MSI-high and MSS colorectal cancer, which might be distinguished by distinct molecular biological features such as lost MLH1 expression, FBXW7 mutations, and TP53 mutations.

Background/Aims: To compare white light imaging (WLI) with linked color imaging (LCI) and blue LASER imaging (BLI) in endoscopic findings of Helicobacter pylori presently infected, previously infected, and uninfected gastric mucosae for visibility and inter-rater reliability. Methods: WLI, LCI and BLI bright mode (BLI-bright) were used to obtain 1,092 endoscopic images from 261 patients according to the Kyoto Classification of Gastritis. Images were evaluated retrospectively by 10 experts and 10 trainee endoscopists and included diffuse redness, spotty redness, map-like redness, patchy redness, red streaks, intestinal metaplasia, and an atrophic border (52 cases for each finding, respectively). Physicians assessed visibility as follows: 5 (improved), 4 (somewhat improved), 3 (equivalent), 2 (somewhat decreased), and 1 (decreased). Visibility was assessed from totaled scores. The inter-rater reliability (intraclass correlation coefficient) was also evaluated. Results: Compared with WLI, all endoscopists reported improved visibility with LCI: 55.8% for diffuse redness; LCI: 38.5% for spotty redness; LCI: 57.7% for maplike redness; LCI: 40.4% for patchy redness; LCI: 53.8% for red streaks; LCI: 42.3% and BLI-bright: 80.8% for intestinal metaplasia; LCI: 46.2% for an atrophic border. For all endoscopists, the inter-rater reliabilities of LCI compared to WLI were 0.73

<b><i>Aims:</i></b> We aimed to clarify the endoscopic/clinicopathological features of superficial non-ampullary duodenal epithelial tumors (SNADETs) based on their mucin phenotypes. <b><i>Methods:</i></b> We analyzed 62 SNADET lesions and classified them based on mucin phenotypic expression. Endoscopic and clinicopathological findings were compared according to mucin phenotypes. <b><i>Results:</i></b> Eleven lesions had the gastric phenotype (GP) and 43 lesions had the intestinal phenotype (IP). All GP lesions were located in the first portion of the duodenum, while most IP lesions (72.1%) were located in the second portion (<i>p</i> &#x3c; 0.01). Tumor size was significantly larger in the GP than in the IP group (14.4 mm vs. 10.2 mm, <i>p</i> &#x3c; 0.05). Reddish color (72.7% in GP vs. 37.2% in IP, <i>p</i> &#x3c; 0.05), type 0-I (72.7% vs. 11.6%, <i>p</i> &#x3c; 0.01), lobular/granular pattern (81.8% vs. 4.7%, <i>p</i> &#x3c; 0.01), and category 4/5 in Vienna classification (81.8% vs. 30.2%, <i>p</i> &#x3c; 0.01) were observed significantly more often in the GP than in the IP group. Regarding findings of magnifying endoscopy with narrow-band imaging (M-NBI), white opaque substance (22.2% in GP vs. 89.7% in IP, <i>p</i> &#x3c; 0.01) and light blue crest (0% vs. 43.6%, <i>p</i> &#x3c; 0.05) were significantly less frequently observed in the GP group. Oval-shaped marginal epithelium (66.7% vs. 17.9%, <i>p</i> &#x3c; 0.01), dense pattern (55.6% vs. 2.6%, <i>p</i> &#x3c; 0.01), and dilatation of the intervening part (100% vs. 12.8%, <i>p</i> &#x3c; 0.01) were more frequently observed in the GP group. <b><i>Conclusions:</i></b> SNADETs showed distinct endoscopic/clinicopathological features according to the mucin phenotype. Tumor location, coloration, macroscopic type, and endoscopic findings including M-NBI are useful to distinguish the mucin phenotypes of SNADETs.

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