Since 2010, I have visited 13 developing Asian countries for endoscopic surveys. I present my experiences in these countries and outline the projects for eradicating gastric cancer related death in Bhutan. In these countries, access to endoscopy is limited to large cities, and there is no significant difference between the incidence and mortality rates of gastric cancer; therefore, gastric cancer is still considered incurable. The role of Helicobacter pylori is poorly understood, including among physicians, and the concept of early-stage gastric cancer is not widely accepted. In most countries, people have never seen early gastric cancer. In contrast, most gastric cancers are detected at an early stage and treated endoscopically and all patients with H. pylori-infected gastritis have access to endoscopic examination followed by H. pylori eradication therapy in Japan. This Japanese model should be introduced to the rest of the world because of the gradual decline in gastric cancer mortality rate it has produced in Japan. We have established a system to rapidly diagnose H. pylori infection and antimicrobial resistance in Bhutan, a country with a population of only 800,000, and launched a gastric cancer eradication project in collaboration with the government of Bhutan. The first step is to train endoscopists. There is an urgent need to train endoscopists, and we are always willing to send endoscopists to Bhutan to provide endoscopic skills; therefore, you may contact us if you are interested.

Vascular lesions of the small intestine are the major causes of small bowel bleeding, accounting for 23-52% of bleeding. Vascular lesions often occur in patients with underlying diseases, such as cirrhosis, valvular heart disease, and ischemic heart disease, and in those undergoing hemodialysis. A hemostatic procedure is selected based on the Yano-Yamamoto classification, which is an endoscopic classification of vascular lesions of the small intestine based on the presence or absence of pulsation. Type 1a and 1b correspond to angioectasia lesions and are treated by argon plasma coagulation (APC) or polidocanol injection therapy. Type 2a and 2b correspond to Dieulafoy lesions and are treated by clip-hemostasis. Type 3 corresponds to arteriovenous malformation and is treated with surgical resection in principle. The rebleeding rate of small intestinal vascular lesions after endoscopic hemostasis has been reported to be 38.5%. Female sex, hereditary hemorrhagic telangiectasia, heart disease, overt bleeding, multiple lesions, and cirrhosis have been reported as predictors of rebleeding. It is important to prevent bleeding by appropriate follow-up (based on the risk factors present) and management of underlying diseases.

A Japanese man in his twenties was diagnosed with esophageal tumor. However, the tumor was not further investigated at the time of diagnosis. At 73 years of age, he was diagnosed with esophageal leiomyoma with calcification after undergoing EGD and boring biopsy. Subsequently, he defaulted follow-up. At 75 years, he was referred to our hospital due to persistent postprandial vomiting. EGD revealed a yellowish-white, hard, rough-surfaced, 30 mm mass covered with normal mucosa in the lower thoracic esophagus. As a result of insufflation during this procedure, the mass detached and fell into the lumen of the esophagus. Because it appeared to be obstructing the esophagus, various endoscopic procedures to shrink the mass were repeatedly performed, culminating in crushing and removal from the stomach by electrohydraulic lithotripsy. Histopathological diagnosis of the retrieved specimen was calcified leiomyoma. Electron microscopic and infrared spectroscopic analyses revealed that the calcified component was carbonate apatite. To the best of our knowledge, this is the first report of a patient with a calcified esophageal leiomyoma that detached and fell into the lumen of the esophagus.

Diffuse large B-cell lymphoma (DLBCL) is a lymphoma characterized by its predilection for the stomach, and endoscopic findings often show soft protrusions with ulceration. We report a case of DLBCL that did not show such typical findings. The patient was a 76 year old male who presented with right neck swelling and malaise of four months duration. After several examinations, he was diagnosed with stage Ⅳ(Lugano classification) primary DLBCL of the right cervical lymph node. Upper gastrointestinal endoscopy showed flat white protrusions of 7 mm in size in the gastric corpus and whitish protrusions with depressed centers in the second part of duodenum. Histopathological examination of these lesions revealed proliferation of lymphoid cells in the interstitium of the lamina propria. Immunohistochemically, the tumor cells were cluster of differentiation (CD)20-positive, CD10-positive, and CD3-negative; Ki-67 labeling index was 90%. These findings led to a diagnosis of DLBCL. This case presented with atypical endoscopic findings of DLBCL such as small, flat white protrusions.

In August 2018, a man in his 80s was referred to our hospital for upper gastrointestinal endoscopy, which revealed a 6-mm, slightly depressed lesion in the lower part of the duodenal bulb. Biopsy showed signet-ring cell carcinoma in the intrinsic layer of the mucosa. Initially, we planned to resect the lesion endoscopically due to the absence of obvious metastasis on contrast-enhanced computed tomography. However, by the time of the treatment in November 2018, the lesion had rapidly increased in volume and presented as a thick depressed lesion with marginal elevation. The lesion was resected en bloc endoscopically. Histologically, it was diagnosed as poorly differentiated adenocarcinoma with signet ring cell carcinoma, featuring a submucosal invasion depth of greater than 1000μm, positive deep tumor margin, and positive lymphatic invasion. Additional surgery including pancreaticoduodenectomy was recommended, but the patient declined and eventually succumbed to cancer in October 2019.

The occurrence of undifferentiated duodenal adenocarcinoma with a gastric phenotype at an early stage is rare. Furthermore, no case reports have documented early-stage duodenal adenocarcinoma showing a rapid progression within a short period. Our case was rare and holds value in understanding the progression of early-stage duodenal adenocarcinoma.

A 71-year-old man was on regular follow up for hepatitis C-related cirrhosis and hepatocellular carcinoma (HCC). At 70 years of age, he had undergone proton beam radiation for HCC located in S8 near the hepatic portal vein and transcatheter arterial chemoembolization in peripheral S6 and the dome (S8). Thereafter, no recurrence of HCC was seen on contrast-enhanced CT/MRI. However, he had recurrent obstructive jaundice and cholangitis due to biliary hemorrhage. Peroral cholangioscopy revealed a white mass with blood clots at the root of the biliary tract in the anterior segment. Biopsy of this mass revealed atypical cells with necrosis and degeneration, and immunostaining for Glypican-3 was positive. Based on these results, he was diagnosed with hepatocellular carcinoma with bile duct invasion. Lenvatinib was administered as chemotherapy for HCC. We report a rare case in which diagnosis and therapeutic intervention were achieved by performing peroral cholangioscopy in a patient with radiological image (CT/MRI) negative hepatocellular carcinoma.

Advances in endoscopic equipment has led to the development of magnifying endoscopy with narrow band imaging (ME-NBI). Furthermore, ultra-magnifying endoscopy (Endocytoscopy: EC), which enables observation at 400-500 x, the same magnification as that of microscopes, has been developed, and its usefulness in the diagnosis of esophageal and colorectal cancer has been reported. However, there are few reports on the usefulness of EC in the diagnosis of gastric cancer, and the usefulness of EC-NBI, which is a combination of EC and NBI, is unknown. Therefore, based on our report on EC-NBI use in the diagnosis of gastric cancer, I discuss tips on the EC-NBI technique and the diagnosis of gastric cancer.

In 2014, colon capsule endoscopy became covered by health insurance in Japan. To improve the excretion rate of the capsule, we investigated a pretreatment method using castor oil and were able to shorten the capsule excretion and examination time in all 20 patients (including 4 patients undergoing dialysis) evaluated. Subsequently, a multi-center joint study was conducted, and it was found that castor oil improved the colon capsule ejection rate; it is currently used in the regimen for polyp visualization recommended by the Japan Capsule Endoscopy Society. Finally, it accompanies the current conditioning and booster medications administered in our institution.

Objectives: Limited information is available on the efficacy and safety of endoscopic resection (ER) of gastric submucosal tumors (SMTs) in Japanese endoscopic practice where ER for gastric tumors is extremely popular.

Methods: We conducted this study to elucidate the current scenario of ER for gastric SMTs in Japanese endoscopic practice. Patients (from 12 institutions) with gastric SMTs who underwent ER were enrolled from the first case until August 2020.

Results: We enrolled 117 patients with 118 lesions. The number of patients who underwent ER increased over the years. The mean endoscopic tumor size was 20±7.2 (8-40) mm. The growth type was primarily intraluminal (90%). The mean resection and wound closure times were 58±38 (range, 12-254) min and 31±41 (range, 3-330) min, respectively. Complete ER was achieved for 117 (99%) lesions. Full-thickness resection rate was 44%; however, only 12 (10%) patients required abdominal paracentesis for decompression. Endoscopic treatments were completed in 115 (97%) lesions, while three lesions required conversions to laparoscopic surgery due to luminal collapse, uncontrolled bleeding, and difficulty in defect closure. Gastrointestinal stromal tumors were the most common pathology (74%). No recurrence was observed during the mean follow-up period of 4.3±2.9 years. The 5-year overall survival rate was 98.9% (95% confidence interval 97.8-100%).

Conclusion: Performance of ER for gastric SMTs is increasing in Japan. The technique seems feasible in Japanese endoscopic practice, warranting further validation in a prospective study.