We describe the management of small colorectal polyps of less than 1 cm size. Image enhancement endoscopy and magnifying observation are useful for the differentiation of hyperplastic polyps, adenomas, and cancers, and it is especially important to exclude cancers with cold polypectomy. Cold polypectomy is rapidly spreading because postoperative bleeding is extremely rare and perforation is almost non-existent. However, EMR should be chosen for lesions suspected of being cancerous, even if they are minute. The use of the latest equipment, including artificial intelligence, has made precise diagnosis and treatment easier.

The causes of acquired gastrointestinal stenosis vary, including advanced cancer, scars after healing of inflammation, scars after endoscopic treatment, and surgical anastomosis. However, the treatment of gastrointestinal stenosis is targeted only when it causes a passage obstruction. In the case of upper gastrointestinal tract stenosis, treatment is performed to allow foods to pass; in the case of lower gastrointestinal tract stenosis, treatment is performed to allow the passage of stool. In cases of advanced cancers that require resection, surgery aimed at relieving the stenosis and a radical cure may be the first choice. However, surgery aimed solely at relieving the stenosis is the last resort in many cases. Especially for benign stenosis, mechanical dilation has long been the first choice of treatment and the method to avoid surgery. In this paper, we describe the current status of endoscopic dilation for the lower gastrointestinal tract stenosis with bougie, balloon dilation, and radial incision and cutting (RIC). As compared to the past, one of the advances is that treatment is often performed using an endoscope to confirm how the stenosis is dilated. However, there has been no breakthrough in discussing the methodology of mechanical dilation. I would also like to describe the current problems and prospects.

A 67-year-old man was referred to our hospital for evaluation of rapid growth in a small gastric submucosal tumor (SMT) during annual surveillance. Endoscopy revealed a large SMT with a giant ulcer in the fornix of the stomach. Evaluation of biopsy specimens confirmed diagnosis of a gastrointestinal stromal tumor (GIST), and we performed partial gastrectomy. Histopathological evaluation of the resected specimen revealed a high-risk GIST. Clinically, small gastric SMTs that show rapid growth are rare; however, most such SMTs are categorized as high-risk GISTs. Although rare, rapid growth detected during surveillance should be considered a clinically significant change. We report a rare case of a rapidly progressive high-risk gastric GIST, together with a literature review.

A 30-year-old woman with epigastric pain and fever was admitted to our hospital. Upper gastrointestinal endoscopy and endoscopic ultrasound revealed an oval cystic tumor. A diagnosis of duodenal duplication was made based on the endoscopic and endosonographic findings. Endoscopic fenestration of the cyst wall was performed on duodenal duplication. Because of the rarity of the disease, only a few cases of duodenal duplication have been reported till date. Herein, we present the details of this case along with a review of literature.

A 57-year-old Japanese male with chronic hepatitis B and alcoholic liver disease underwent radiofrequency ablation for S3 and S7 hepatocellular carcinoma (HCC) one and a half year ago. Follow-up gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (EOB-MRI) showed a growing 2-cm hepatic tumor in the lateral segment S2, without arterial phase enhancement but with low-intensity portal phase images. As typical findings of HCC, such as hypervascularity, were not found on MRI, contrast-enhanced (CE) ultrasonography was planned. However, performing extracorporeal ultrasonography was difficult because of left lung interference; therefore, EUS was employed. The tumor showed slightly hypoechoic, and CE-EUS using perflubutane showed early arterial phase enhancement and delayed phase washout. Thus, HCC was diagnosed. As the patient chose minimally invasive treatment for the HCC, EUS-guided ethanol injection was performed as ablation therapy. Treatment was successful and without complications, and no local recurrence was observed after 1 year and 8 months. EUS is useful in diagnosing and treating HCC when extracorporeal US is difficult to perform, such as in the lateral segment where lung air interferes with imaging.

Perineurioma (PN), a benign tumor derived from perineurial cells, rarely occurs in the gastrointestinal tract. PN and a sessile serrated lesion (SSL) observed in a single tumor is extremely rare; the lesion that originated first remains unknown. We describe three lesions with SSL and concomitant PN within the same lesion. Histopathological evaluation of all three lesions showed interstitial spindle cell proliferation. Immunohistochemical analysis revealed cells with weak-to-strong immunopositivity for epithelial membrane antigen, glucose transporter-1, and Claudin-1. Therefore, we diagnosed PN in all three lesions. Of the three lesions, two measured 5 mm in size, and it was difficult to determine the lesion that had originated first. However, based on observation of a laterally spreading tumor lesion, PN was detected only in a small bulge. Further accumulation of these lesions is needed to elucidate the origin of PN accompanied by SSL.

Various new methods have been devised for closing mucosal defects after ESD to reduce postoperative adverse events. However, no method has been developed for complete closure of the thick mucosa and muscular layer of the stomach without dead space between the mucosa and muscular layer. Here, we report a new method for defect closure, the reopenable clip over the line method (ROLM); this new method uses a nylon line and a hole in the tooth of a reopenable clip. This method reduces dead space and closes defects by grasping the clip at the edge of the defect and the nearby muscle layer and pulling the line by hand. Defect closure can be achieved by repeatedly placing a clip on the edge of the mucosal defect on one side and the muscle layer and then placing the next clip on the edge of the mucosal defect on the contralateral side and the muscle layer. ROLM is a simple method because it eliminates the need to clip both sides of the mucosal defect with a single clip. In addition, ROLM can be performed for post-ESD mucosal defects in the colon and duodenum, where endoscopic maneuverability is poor.

The incidence of superficial non-ampullary duodenal epithelial tumors (SNADETs) has increased in recent years. However, duodenal ESD is technically more difficult than ESD in other organs and is associated with high complication rates. Laparoscopy and endoscopy cooperative surgery (LECS) is a useful alternative that overcomes the challenges associated with ESD. In this article, we describe the clinical practice of LECS for SNADETs.

Objectives: Gastrointestinal endoscopy (GIE) is useful for the early detection and treatment of many diseases; however, GIE is considered a high-risk procedure in the coronavirus disease 2019 (COVID-19) pandemic era. This study aimed to explore the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positivity in saliva and gastrointestinal fluids to which endoscopy medical staff are exposed.

Methods: The study was a single-center cross-sectional study. From June 1 to July 31, 2020, all patients who underwent GIE at Yokohama City University Hospital were registered. All patients provided 3 mL of saliva. For upper GIE, 10 mL of gastric fluid was collected through the endoscope. For lower GIE, 10 mL of intestinal fluid was collected through the endoscope. The primary outcome was the positive rate of SARS-CoV-2 in saliva and gastrointestinal fluids. We also analyzed serum-specific antibodies for SARS-CoV-2 and patientsʼ background information.

Results: A total of 783 samples (560 upper GIE and 223 lower GIE samples) were analyzed. Polymerase chain reaction (PCR) on saliva samples did not show any positive results in either upper or lower GIE samples. However, 2.0% (16/783) of gastrointestinal fluid samples tested positive for SARS-CoV-2. No significant differences in age, sex, purpose of endoscopy, medication, or rate of antibody test positivity were found between PCR positive and PCR negative cases.

Conclusions: Asymptomatic patients, even those with no detectable virus in their saliva, had SARS-CoV-2 in their gastrointestinal tract. Endoscopy medical staff should be aware of infection when performing procedures. The study was registered as UMIN000040587.