Gastrointestinal endoscopy is an essential tool in gastrointestinal care. It plays a key role not only in the examination and diagnosis but also in the treatment of gastrointestinal issues. Endoscopic care includes cholangiopancreatography, ultrasound endoscopy, ESD, hemostasis, and foreign body removal, in addition to the usual upper endoscopy and colonoscopy. Various types of training models and simulators have been developed for application in endoscopic care. They are used for practice by beginner endoscopists and for teaching residents or students. Training models have the advantage of simplicity and low cost; nevertheless, simulators are superior, in that they allow training in a wide variety of endoscopic examinations and procedures. We hope that training models and simulators can be used effectively in practice and instruction to improve individual endoscopic skills and actual clinical work.

Endoscopic findings are important for the diagnosis of various types of enteritis. However, because various conditions have similar endoscopic findings, histological analysis of biopsy specimens is crucial for differentiating among them and understanding their background factors. The characteristic endoscopic findings of various gastrointestinal conditions include edema, low vascular permeability, and mucosal exfoliation in gastrointestinal graft-versus-host disease enteritis; map-like erosions and shallow and round or longitudinal ulcers in non-steroidal anti-inflammatory drug (NSAIDs)-induced enteritis; pseudomembranes in Clostridioides difficile infection; edema, granular mucosa, cracks, and mucosal tears in collagenous colitis; and redness, granular mucosa, edematous mucosa, and reduced translucency in immune-related Adverse Events (irAE) enteritis. Recognizing the characteristic endoscopic findings of each disease can significantly facilitate diagnosis.

A 78-year-old man with intrahepatic cholangiocarcinoma was followed up after the right lobectomy of his liver. He subsequently developed tarry stools and underwent endoscopy, which revealed esophageal varices (LmF3CwRC1). No hepatic encephalopathy was evident, but at 107 μg/dL, the ammonia level was elevated. As the patient had a low platelet count of 50,000/μL, he was administered 3 mg/day Lustrombopag for a week, which increased the count. Endoscopic sclerotherapy was then performed, using ethanolamine olate to occlude the left gastric vein. Thereafter, the ammonia level normalized rapidly. Portal hypertension sometimes occurs after hepatectomy, and esophageal varices may develop. Occluding the giant tree-like esophageal varices using endoscopic sclerotherapy is considered to block the collateral blood circulation, resulting in a decrease in the ammonia level. In patients with esophageal varices and a high ammonia level, shunt occlusion may reduce the ammonia level. This was also considered to be the appropriate active intervention in the present case of pipeline esophageal varices after hepatectomy in which the ammonia level normalized after endoscopic sclerotherapy.

We report a case of a 71-year-old man with gastric angiosarcoma. Two round lung tumors were found accidentally on chest CT performed as part of an examination for abnormal liver function. These tumors appeared to be metastatic. Esophagogastroduodenoscopy revealed a red flat, slightly elevated mass in the greater curvature of stomach. Pathological examination of biopsied stomach tissues revealed proliferation of malignant cells. Immunostaining were positive for ERG and CD31. Based on these findings, the patient was diagnosed as having gastric angiosarcoma with lung metastases. The gastric and lung tumor masses diminished in size with the application of chemotherapy with paclitaxel. However, after seven chemotherapy courses, the gastric tumor enlarged and had a purplish-red type 2 tumor-like appearance. Therefore, we changed the chemotherapy regimens; however, it was ineffective. The patient died of serious bleeding in the digestive duct 11 months after the first visit. We encountered a rare case of angiosarcoma in the stomach with multiple distant metastases and found morphological changes in the tumor on conducting esophagogastroduodenoscopy. Further progress in the early diagnosis and treatment of angiosarcoma is needed to improve the prognosis of the affected patients.

A 65-year-old man previously treated for Helicobacter pylori infection underwent hemodialysis for chronic renal failure and received lanthanum carbonate for 3 years. Lanthanum carbonate was approved for preventing hyperphosphatemia in patients undergoing dialysis for chronic renal failure in 2009, and is considered a highly safe drug because it shows little absorption in the gastrointestinal tract. Screening endoscopy demonstrated a reddish depressed lesion on the lesser curvature of the lower gastric body, and fine white granular discoloration was noted throughout the stomach, with intestinal metaplasia and mucosal atrophy. Biopsy specimens from the depressed lesion and surrounding mucosa revealed adenocarcinomas, including the presence of macrophages engulfing the brownish substance, which was suspected to be lanthanum carbonate in the nontumor gastric mucosa surrounding the cancer lesions. We made a diagnosis of intramucosal gastric cancers and performed one-piece ESD to remove both cancers. Based on the pathological examination, the two gastric cancer lesions were intramucosal well-differentiated adenocarcinomas with little lanthanum deposition in the tumor regions. Since lanthanum deposition may be associated with regenerative change, intestinal metaplasia, and/or foveolar hyperplasia of the gastric mucosa, endoscopic screening for gastric cancer may be effective in patients with chronic renal failure who are receiving lanthanum carbonate.

A 94-year-old woman reported to a neighborhood hospital with a complaint of orbital pain and diarrhea. Abdominal computed tomography showed a thickening of the ascending colon, after which she was referred to our hospital. As colorectal obstruction was noted, obstructive colorectal cancer was suspected and CS was performed urgently; cancer of the ascending colon and rectum was diagnosed. Since the ascending colon cancer was not passable through the scope, a self-expanding metallic stent was inserted into the ascending colon. After four days, the patient developed abdominal distension again and recurrent bowel obstruction was suspected. Abdominal contrast-enhanced computed tomography showed bowel obstruction caused by the impaction of a highly resorbed foreign body, suspected to be a seed, in the stent. The foreign body was removed endoscopically and was identified as a Japanese apricot pit. Bowel obstruction improved and the patient underwent interval resection of the colon.

Although there have been many reports on intestinal obstruction caused by dietary foreign bodies such as seeds, obstruction within an implanted colonic stent is rare, and we report this case along with a review of literature.

Crohnʼs disease(CD) is a chronic progressive, destructive inflammatory disease characterized by repeated inflammation and intestinal damage, mainly in the small and large intestines. Assessment and quantification of mucosal inflammation by small bowel capsule endoscopy are important because small bowel lesions are often poorly reflected in clinical symptoms and biomarkers. Lewis Score and the Capsule Endoscopy Crohnʼs Disease Activity Index are commonly used small bowel capsule endoscopy scores for CD. Although extensive evidence is available for these scores, it is important to note that judging by scores alone may lead to a misdiagnosis of the pathophysiology of CD, which comprises inflammation and organic changes such as stenosis. The information reported should include patency capsule evaluation results, history of intestinal surgery, and intestinal transit time. In addition, postoperative anastomotic ulcers and stenosis sites that are difficult to determine based on the score and characteristic gastric lesions such as those with a bamboo-joint appearance and duodenal notch-like depression should be noted without fail.

Drainage techniques for acute cholecystitis include percutaneous transhepatic drainage (PTGBD), endoscopic transpapillary gallbladder drainage (ETGBD), and endoscopic ultrasound-guided gallbladder drainage (EUS-GBD). ETGBD is a non-puncture procedure through a physiological route; hence, it can be performed on patients with bleeding tendencies or ascites. However, the technical success rate of ETGBD is inferior to that of PTGBD and EUS-GBD owing to the technical difficulty of selective cannulation to the cystic duct. A safe and successful ETGBD requires mastery of the basic technique and ability to troubleshoot during difficult cases.

The number of artificial intelligence (AI) tools for colonoscopy on the market is increasing with supporting clinical evidence. Nevertheless, their implementation is not going smoothly for a variety of reasons, including lack of data on clinical benefits and cost-effectiveness, lack of trustworthy guidelines, uncertain indications, and cost for implementation. To address this issue and better guide practitioners, the World Endoscopy Organization (WEO) has provided its perspective about the status of AI in colonoscopy as the position statement. WEO Position Statement: Statement 1.1: Computer-aided detection (CADe) for colorectal polyps is likely to improve colonoscopy effectiveness by reducing adenoma miss rates and thus increase adenoma detection; Statement 1.2: In the short term, use of CADe is likely to increase health-care costs by detecting more adenomas; Statement 1.3: In the long term, the increased cost by CADe could be balanced by savings in costs related to cancer treatment (surgery, chemotherapy, palliative care) due to CADe-related cancer prevention; Statement 1.4: Health-care delivery systems and authorities should evaluate the costeffectiveness of CADe to support its use in clinical practice; Statement 2.1: Computer-aided diagnosis (CADx) for diminutive polyps (≤5 mm), when it has sufficient accuracy, is expected to reduce health-care costs by reducing polypectomies, pathological examinations, or both; Statement 2.2: Health-care delivery systems and authorities should evaluate the cost-effectiveness of CADx to support its use in clinical practice; Statement 3: We recommend that a broad range of high-quality costeffectiveness research should be undertaken to understand whether AI implementation benefits populations and societies in different health-care systems.