In Western countries, the incidence of esophageal adenocarcinoma began to increase in the 1960s to 1970s, and sharply increased in the 1980s to 2000s. In Japan, a series of recent reports indicated that the incidence of esophageal adenocarcinoma began to increase in the 2000s to 2010s, 40 to 50 years behind the situation in Western countries. The time lag in the onset of esophageal adenocarcinoma between Western countries and Japan may be related to the difference in the time when the Helicobacter pylori (H. pylori) infection rate began to decline. Whether or not a rapid increase in esophageal adenocarcinoma cases that occurred in Western countries can also occur in Japan in the future is of great concern. At present, such a rapid increase in esophageal adenocarcinoma cases is unlikely to occur in Japan due to the lower risk of conditions predisposing to gastroesophageal reflux disease (GERD) such as higher gastric acid secretion level and obesity rate in Japanese, and due to ethnic differences in susceptibility to esophageal adenocarcinoma. However, the incidence of esophageal adenocarcinoma in Japan is expected to gradually increase due to the further decrease in the H. pylori infection rate.

Endoscopic ultrasonography-guided celiac plexus neurolysis (EUS-CPN) is performed to alleviate upper abdominal pain. The response rate has been reported to be 46％−81％, and this procedure has made it possible to reduce the opioid dose. In two randomized controlled studies, the efficacy of EUS-CPN that was performed at an early pain stage was evaluated; the results of these two studies have been discordant since its efficacy appears to be limited when appropriate medications are combined. Given the possible severe adverse events and negative effects on prognosis, EUS-CPN should be performed for reasons such as severe pain that cannot be controlled using drugs, intolerance to opioids, hindrance towards frequent hospital visits, and financial problems.

A few studies have reported spontaneous submucosal hematoma of the esophagus, but our review of the literature revealed that formation of a submucosal hematoma following endoscopic retrograde cholangiopancreatography (ERCP) is very rare. We report a case of submucosal hematoma of the esophagus following ERCP in a patient with pemphigus.

A 68-year-old man was admitted to our hospital for treatment of pemphigus, and a consultation with our department was requested for examination of liver damage. The patient underwent ERCP and biliary drainage for biliary stricture. When removing the duodenal endoscope, a submucosal hematoma extending along the long axis was found in the middle and lower esophagus. Upper gastrointestinal endoscopy that had been performed before ERCP for screening showed no esophageal disease associated with pemphigus. Seven days after ERCP, endoscopy showed improvement of the esophageal submucosal hematoma with a superficial ulcer and mucosal bridge. After conservative treatment, the patientʼs subsequent clinical course was uneventful.

Patients at high risk for bleeding and patients with pemphigus are especially prone to complications from ERCP. Therefore, we should perform the endoscopic procedure in these patients more carefully and protectively to reduce mechanical stimulation.

A 69-year-old man underwent left nephrectomy for left clear cell renal cell carcinoma (pT1bN0M0 Stage I, Fuhrman grade:G2＞G1) in 2008. Surgical resections of mediastinal lymph node metastasis and lung metastasis were performed in 2012 and 2013, respectively, and interferon therapy was subsequently continued. In August 2018, the patient developed acute cholecystitis. When upper gastrointestinal endoscopy was performed as a preoperative examination prior to cholecystectomy, a 10-mm reddened, elevated lesion was found near the esophagogastric junction. Histological examination of biopsy specimens led to the diagnosis of metastasis of clear cell renal cell carcinoma. Endoscopic mucosal resection was performed after consultation with the urology department, as local excision of solitary metastatic foci of renal cell carcinoma has been demonstrated to significantly improve prognosis. We present the significance and benefits of endoscopic therapy of metastatic clear cell renal cell carcinoma.

A 77-year-old woman presented with epigastric pain and underwent upper gastrointestinal endoscopy. Five early-stage gastric cancers were found in the stomach. Background endoscopic findings of the gastric mucosa showed an intestinal metaplasia in the antrum. A clear vascular image was obtained from the gastric body to the fornix, and atrophic changes were observed. Fasting serum gastrin and serum anti-H. pylori-IgG antibody levels were 410 pg/ml and＜3.0U/ml, respectively. Anti-parietal cell antibody (measured 80 times) and anti-intrinsic factor antibody were positive. Background histological findings of gastric mucosa showed marked atrophic changes and intestinal metaplasia in the pyloric gland. The proper fundic gland was absent. Moreover, intestinal metaplasia, an endocrine cell micronest, and enterochromaffin-like cells hyperplasia were observed. Therefore, we diagnosed autoimmune gastritis based on the endoscopic and serological findings.

This case is an autoimmune gastritis with atrophy and intestinal metaplasia in the pyloric gland area, and it is possible that the five gastric cancers developed from the background gastric mucosa.

Case 1 was a 62-year-old male taking mesalazine for ulcerative colitis. Total colonoscopy performed due to hematochezia revealed a 20-mm-sized, slightly elevated lesion in the ascending colon. However, no malignant findings were found, and three months later, the lesion had almost disappeared. Case 2 was an 84-year-old male in his 80s taking mesalazine for ulcerative colitis. Esophagogastroduodenoscopy performed due to melena showed no hemorrhage. Total colonoscopy showed a thick prominent lesion with dense nodules in the ascending colon. However, no malignant findings were found, and three years later, the lesion was considered to have become a scar and scattered inflammatory polyps. These findings may be characteristic endoscopic findings of ulcerative colitis.

Self-expandable metallic stent placement is widely performed for malignant colonic obstructions. However, it is technically difficult to place a colonic stent for a rectal tumor, especially a tumor close to the dentate line, in the proper position without resulting in anal pain after stent placement. Recently, a proximal release-type (PR) stent for malignant rectal obstruction has been approved for clinical use by PMDA and covered by health insurance in Japan. This new stent is easy to place because of its structure. During placement of the PR stent, we push the delivery system of this stent during its release. The pushing movement makes it easier to place the PR stent in contrast with the conventional stent, which requires a pull-back movement. The distal edge of the PR stent is placed at the distal tumor edge to facilitate positioning of the stent close to the dentate line.

We placed the PR stent in 4 patients with malignant lower rectal obstructions under palliative care. We succeeded in all four patients, and all of them had no anal pain after stent placement even though they had obstruction within 5 cm of the dentate line. Anal pain and other discomforts after stent placement can severely worsen the patients’ quality of life. Although our study included only four successful cases of PR stent placement for lower rectal obstruction, none of them had anal pain after the procedure.

In bridge-to-surgery (BTS) cases, the conventional stent which requires a complicated pull-back movement during its release, often becomes placed on the anal side, and it is not suitable for rectal obstruction. In contrast, the PR stent is easier to place and placement on the anal side is prevented. Therefore, a PR stent might also be suitable for rectal obstruction in BTS cases.

The PR colonic stent showed good results of decompression for lower rectal obstructions close to the dentate line. Further studies are warranted to investigate the new stent’s efficacy and indications.

Autoimmune gastritis (AIG) is a special type of gastritis in which parietal cells are destroyed due to autoimmune abnormalities such as anti-parietal cell antibodies that are produced against the proton pump (H^＋/K^＋ ATPase) in the process. AIG is characterized by reverse atrophy on endoscopy. In addition, findings such as sticky adherent dense mucus, remnant oxyntic mucosa, and circular wrinkle-like patterns in the antrum can be observed. Endoscopic images of early-stage AIG obtained from recent reports have shown features such as longitudinal reddish pseudopolyp-like nodules, thickened and edematous mucosa, and mosaic-like patterns of the pits on the greater curvature of the corpus.

Gastric cancer complicated with AIG is an early intestinal cancer that is located mainly in the L to M region. The serum gastrin level and prevalence of pernicious anemia were higher in gastric cancer cases complicated with AIG than in non-gastric cancer AIG cases. Furthermore, histological analysis of the background gastric mucosa in gastric cancer cases complicated with AIG revealed severe atrophy and mild mononuclear infiltration compared with non-gastric cancer AIG cases.

Gastric neuroendocrine tumors complicated with AIG were classified as type I by Rindi et al. These tumors, located in the corpus, have a small diameter and are accompanied by hypergastrinemia. They have a good clinical prognosis. The predominant colors in the tumor are pale yellow and red. Dilated vessels, redness, and depressions may be observed in the center of the tumor.

According to the current Japanese guidelines, cold snare polypectomy (CSP) is classified as a high-risk endoscopic procedure for bleeding and should be managed according to the risk of thromboembolism. However, according to previous reports, the risk of bleeding after CSP may be low. Therefore, antiplatelet agents and warfarin can continue to be taken before CSP, and direct oral anticoagulants (DOACs) can be discontinued for one day after CSP, rather than before.

In patients who are taking an antithrombotic agent, CSP can be performed in a standard manner regardless of the antithrombotic agent they are taking. The lesion should be bluntly removed with the surrounding normal mucosa using a snare without electrocautery. After resection, if bleeding does not tend to weaken, hemostasis using an endoclip should be performed. The bleeding that occurs immediately after resection should be washed and suctioned as much as possible, and the patient should be advised that some reddish fluid may be excreted.

CSP was originally indicated for adenomas less than 10 mm in size, but it may be indicated for lesions greater than 10 mm depending on the circumstances. The patientʼs prognosis should be carefully considered, and the indications for the CSP treatment itself and efficacy should also be carefully considered.

In recent years, artificial intelligence (AI) has been found to be useful to physicians in the field of image recognition due to three elements: deep learning (that is, CNN, convolutional neural network), a high-performance computer, and a large amount of digitized data. In the field of gastrointestinal endoscopy, Japanese endoscopists have produced the worldʼs first achievements of CNN-based AI system for detecting gastric and esophageal cancers. This study reviews papers on CNN-based AI for gastrointestinal cancers, and discusses the future of this technology in clinical practice. Employing AI-based endoscopes would enable early cancer detection. The better diagnostic abilities of AI technology may be beneficial in early gastrointestinal cancers in which endoscopists have variable diagnostic abilities and accuracy. AI coupled with the expertise of endoscopists would increase the accuracy of endoscopic diagnosis.