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Appendiceal mucinous tumors (AMTs) include low-grade mucinous appendiceal neoplasms (LAMNs), high-grade mucinous appendiceal neoplasms (HAMNs), and mucinous adenocarcinomas (MACs). We collected 51 AMT samples (LAMN: 34, HAMN: 8, MAC: 9). Three of the eight HAMN cases contained LAMN components, and four out of nine MAC cases contained LAMN and/or HAMN components within the tumor. A next-generation sequencing (NGS) cancer hotspot panel was used to analyze 11 pure LAMN, 4 HAMN, and 3 MAC cases. The results revealed KRAS and GNAS as the most frequently mutated genes. Sanger sequencing was then performed to detect KRAS, GNAS, and TP53 mutations in the remaining 31 cases and RNF43 mutations in all cases. KRAS/GNAS and TP53 mutations occurred exclusively in pure LAMNs; however, five LAMN cases had mutations in both KRAS and GNAS. RNF43 mutations almost exclusively occurred with KRAS/GNAS mutations in pure LAMNs. In MAC and HAMN, KRAS/GNAS mutation status was nearly preserved between lower-grade areas. Most of the detected RNF43 mutations was missense type. RNF43 mutations were detected in both components of MAC with lower-grade area; however, RNF43 mutations detected in these two lesions were entirely different. RNF43 mutations were detected in only one of the eight HAMN patients, which was the sole case without pseudomyxoma peritonei (PMP). None of the four MAC patients with RNF43 mutation showed PMP. These findings suggest that RNF43 mutations occur at a later stage of MAC development and do not associate with PMP. Furthermore, a gradual transition from LAMN to MAC via HAMN could be considered.

BackgroundRecently, Helicobacter pylori (HP)-uninfected gastric mucosal cancer has been reported; however, the clinicopathological and molecular features of HP-uninfected gastric cancer have not been elucidated.MethodsWe evaluated the clinicopathological, immunohistochemical, and genetic alterations in HP-uninfected early gastric adenocarcinoma using next-generation sequencing (NGS).ResultsAmong 968 primary early gastric carcinomas, 64 (6.6%) were HP-uninfected gastric adenocarcinoma and were pathologically classified as gastric adenocarcinoma of fundic-gland type (GA-FG, n = 39), differentiated gastric adenocarcinoma (DGA, n = 16), and signet-ring cell carcinoma (SRCC, n = 9). Based on the expression profile of the mucin core protein, DGAs were classified into a gastrointestinal phenotype showing either MUC5AC or MUC6 expression and MUC2 or CD10 expression simultaneously (n = 5), and a gastric phenotype (n = 11) showing either MUC5AC or MUC6 expression. All DGAs with a gastrointestinal phenotype shared similar endoscopic characteristics, such as reddish depressed lesions in the antrum. In contrast, DGAs with a gastric phenotype exhibited several distinct endoscopic features, including a raspberry-shaped appearance and whitish flat-elevated appearance; the former expressed only MUC5AC and the latter exhibited co-expression of MUC5AC and MUC6. Among 16 HP-uninfected DGAs, seven were subjected to NGS. APC was recurrently mutated in DGA (42.9%) and was enriched in DGAs with a gastrointestinal phenotype (75%).ConclusionsOverall, HP-uninfected gastric adenocarcinomas showed distinct clinicopathologic and endoscopic characteristics. Furthermore, HP-uninfected DGAs, especially those with a gastrointestinal phenotype, may be characterized by recurrent APC mutations.

BackgroundGastric adenocarcinoma of fundic-gland type (GA-FG) is a rare variant of gastric neoplasia. However, the etiology, classification, and clinicopathological features of gastric epithelial neoplasm of fundic-gland mucosa lineage (GEN-FGML; generic term of GA-FG related neoplasm) are not fully elucidated. We performed a large, multicenter, retrospective study to establish a new classification and clarify the clinicopathological features of GEN-FGML.MethodsOne hundred GEN-FGML lesions in 94 patients were collected from 35 institutions between 2008 and 2019. We designed a new histopathological classification of GEN-FGML using immunohistochemical analysis and analyzed via clinicopathological, immunohistochemical, and genetic evaluation.ResultsGEN-FGML was classified into 3 major types; oxyntic gland adenoma (OGA), GA-FG, and gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM). In addition, GA-FGM was classified into 3 subtypes; Type 1 (organized with exposure type), Type 2 (disorganized with exposure type), and Type 3 (disorganized with non-exposure type). OGA and GA-FG demonstrated low-grade epithelial neoplasm, and GA-FGM should be categorized as an aggressive variant of GEN-FGML that demonstrated high-grade epithelial neoplasm (Type 2 > 1, 3). The frequent presence of GNAS mutation was a characteristic genetic feature of GEN-FGML (7/34, 20.6%; OGA 1/3, 33.3%; GA-FG 3/24, 12.5%; GA-FGM 3/7, 42.9%) in mutation analysis using next-generation sequencing.ConclusionsWe have established a new histopathological classification of GEN-FGML and propose a new lineage of gastric epithelial neoplasm that harbors recurrent GNAS mutation. This classification will be useful to estimate the malignant potential of GEN-FGML and establish an appropriate standard therapeutic approach.

Aims: We aimed to clarify the endoscopic/clinicopathological features of superficial non-ampullary duodenal epithelial tumors (SNADETs) based on their mucin phenotypes. Methods: We analyzed 62 SNADET lesions and classified them based on mucin phenotypic expression. Endoscopic and clinicopathological findings were compared according to mucin phenotypes. Results: 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 (p < 0.01). Tumor size was significantly larger in the GP than in the IP group (14.4 mm vs. 10.2 mm, p < 0.05). Reddish color (72.7% in GP vs. 37.2% in IP, p < 0.05), type 0-I (72.7% vs. 11.6%, p < 0.01), lobular/granular pattern (81.8% vs. 4.7%, p < 0.01), and category 4/5 in Vienna classification (81.8% vs. 30.2%, p < 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, p < 0.01) and light blue crest (0% vs. 43.6%, p < 0.05) were significantly less frequently observed in the GP group. Oval-shaped marginal epithelium (66.7% vs. 17.9%, p < 0.01), dense pattern (55.6% vs. 2.6%, p < 0.01), and dilatation of the intervening part (100% vs. 12.8%, p < 0.01) were more frequently observed in the GP group. Conclusions: 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.

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 map-like 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 0.73–0.87. Conclusion: The visibility of each endoscopic finding was improved by LCI while that of intestinal metaplasia was improved by BLI-bright.

Background/Aims Vonoprazan is a new a potassium-competitive acid blocker (P-CAB) that was recently developed in Japan. However, vonoprazan’s efficacy in healing gastric ulcers after endoscopic submucosal dissection (ESD) remains controversial. This study aimed to compare the efficacy of P-CABs and proton pump inhibitors (PPIs) in healing post-ESD ulcers. Materials and Methods This prospective randomized controlled trial (UMIN000017386) enrolled 40 patients with gastric neoplasia, who underwent ESD at our hospital from April 2015 to January 2016. Before ESD, patients were randomly divided into the following two groups: group V, vonoprazan 20 mg/day; or group R, rabeprazole 10 mg/day. Medications were taken 1 day before to 4 weeks after ESD. The ESD-induced artificial ulcer size was measured just after ESD and 4 weeks after ESD to calculate the reduction rate as follows: (ulcer area 4 weeks after ESD)/(ulcer area just after ESD) × 100. Results Eighteen patients in group V and 15 patients in group R were analyzed. The mean reduction rate was significantly different in groups V and R (93.3% vs 96.6%, respectively). Post-ESD bleeding was observed in two patients in group R and drug-induced hepatic injury in one patient in group R. Conclusion Rabeprazole facilitated the healing process post-ESD.

Introduction: Whether the incidence of reflux esophagitis (RE) increases after the eradication of Helicobacter pylori (H. pylori) is controversial. Few reports have evaluated the presence or absence of RE after a long period of time, taking into account the degree of atrophy and/or administration of acid secretion inhibitors. We investigated the relationship between H. pylori and RE taking into account these factors. Methods: This was a retrospective cohort study with approval by the Ethics Committee. Patients who succeeded in H. pylori eradication treatment, and in whom there were images of the gastroesophageal junction on endoscopic examinations within 1 year before eradication treatment and more than 3 years after eradication were included. The degrees of RE and atrophy were retrospectively determined from the endoscopic images. The prevalence of RE before and after eradication and the incidence of newly developed RE after eradication between patients with or without atrophy improvement were compared using Fisher’s exact test. Results: A total of 185 cases (male:female = 104:81; mean age, 63.5 years; mean observation period, 6.4 years) were examined. The prevalence of RE before and after eradication was 1.6% (3/185) and 7.0% (13/185), respectively (P = 0.019). RE was present in 8 (7.5%) of 106 cases with closed-type atrophy and in 5 (6.3%) of 79 cases with open-type atrophy after eradication (P = 0.75). Atrophy improved after eradication in 56 cases, of whom 4 (7.1%) had new onset of RE; the degree of atrophy did not improve in 126 cases, of whom 7 (5.4%) had new onset of RE (P = 0.74). There was no difference between the percentage of cases who took acid secretion inhibitors before and after eradication (P = 0.14). Conclusion: The prevalence of RE increased a long time after eradication, even in patients who were taking an acid secretion inhibitor. The prevalence of RE was not related to the degree of atrophy or change in atrophy.

Background and Aim: Inhibition of gastric acid secretion is important for eradicating Helicobacter pylori. Vonoprazan (VPZ) is a strong, long-lasting inhibitor of gastric acid secretion. Studies that examined the effectiveness of VPZ-based triple therapy in second-line treatment have been performed. However, there have been no randomized controlled studies to compare the effect between VPZ-based triple therapy and proton pump inhibitor (PPI)-based triple therapy in second-line treatment, and it is not known which is more effective between VPZ-based and PPI-based therapies. This study aimed to compare the effectiveness of second-line triple therapies including VPZ or rabeprazole (RPZ) as the PPI. Methods: Eligible patients with H. pylori infection who failed first-line triple therapy were assigned randomly to the VPZ [VPZ40 mg/day, amoxicillin (AMPC) 1500 mg/day, metronidazole (MNZ) 500 mg/day] or RPZ (RPZ20 mg/day, AMPC1500 mg/day, MNZ500 mg/day) group. A 13C-urea breath test result of less than 2.5% was considered as successful eradication. Results: In total, 46 and 41 patients were analyzed as intention to treat (ITT) and per protocol (PP), respectively. Eradication rates in the VPZ and RPZ groups were 73.9% [95% confidence interval (CI) 51.6–89.8%] and 82.6% (95% CI 61.2–95.0%) based on ITT analysis, respectively (p = 0.72). Based on PP analysis, the eradication rates in the VPZ and RPZ groups were 89.5% (95% CI 66.9–98.7%) and 86.4% (95% CI 65.1–97.1%), respectively (p = 1.00). Two patients in the VPZ group and one in the RPZ group discontinued treatment due to side effects (p = 1.00). Conclusion: There were no significant differences in efficacy and safety between second-line therapies including VPZ or RPZ.

Background and Objectives: A novel synthetic self-assembling peptide, PuraStat, has been introduced as a hemostatic agent. This case series aimed to evaluate the clinical efficacy of PuraStat for gastrointestinal bleeding during emergency endoscopy. Cases: Twenty-five patients with gastrointestinal bleeding who had undergone emergency endoscopy with PuraStat between August 2021 and December 2022 were retrospectively examined. Six patients were receiving antithrombotic agents, and ten patients with refractory gastrointestinal bleeding had undergone at least one endoscopic hemostatic procedure. The breakdown of bleeding was gastroduodenal ulcer/erosion in 12 cases, bleeding after gastroduodenal or colorectal endoscopic resection in 4 cases, rectal ulcer in 2 cases, postoperative anastomotic ulcer in 2 cases, and gastric cancer, diffuse antral vascular ectasia, small intestinal ulcer, colonic diverticular bleeding, and radiation proctitis in each case. The method of hemostasis was only PuraStat application in six cases, and hemostasis in combination with high-frequency hemostatic forceps, hemostatic clip, argon plasma coagulation, and hemostatic agents (i.e., thrombin) in the remaining cases. Rebleeding was observed in three cases. Hemostatic efficiency was observed in 23 cases (92%). Conclusions: PuraStat has the expected hemostatic effect on gastrointestinal bleeding during emergency endoscopy. The use of PuraStat should be considered in emergency endoscopic hemostasis of gastrointestinal bleeding.