Accurate histopathological diagnosis is important in endoscopic practice. Effective coordination between endoscopists and pathologists is necessary for accurate results. Endoscopists play an important role in histopathological diagnosis, including in specimen collection and processing. Therefore, knowledge of “pathology” is essential to improve the diagnostic abilities of endoscopists. In this review, we discuss the key issues that endoscopists should consider regarding the handling of specimens acquired during endoscopic examinations.

A 71-year-old man presented to our hospital due to diarrhea and weight loss that had persisted for about 2 months. The upper and lower gastrointestinal endoscopy revealed various lesions with different morphologies in the esophagus, stomach, duodenum, ileum, and colon. Biopsies from each lesion resulted in the diagnosis of a monomorphic epitheliotropic intestinal T-cell lymphoma. There is no report of total gastrointestinal involvement in this disease, and we consider this case to be valuable.

A 43-year-old man underwent annual gastrointestinal endoscopy since 2016 for surveillance of multiple small pale antral lesions, which were not evaluated histopathologically. Biopsy performed for the first time in 2020 revealed a signet-ring cell carcinoma. He underwent distal gastrectomy, and histopathological examination of the surgical specimen revealed 42 small lesions, all of which were diagnosed as carcinoma in situ. We suspected hereditary diffuse gastric cancer (HDGC) and performed genetic analysis, which revealed the CDH1 germline pathogenic variant of the cancer, and the patient was definitively diagnosed with HDGC.

A 26-year-old woman presented to a local clinic for abdominal pain and fever. She was referred to our hospital for treatment of a gastric submucosal tumor-like lesion, which was detected at the local clinic. Endoscopy revealed a submucosal tumor-like lesion with a depression at the apex in the gastric antrum. Contrast-enhanced CT revealed a cystic lesion (approximately 40mm) with increased density of surrounding fatty tissue, which was diagnosed as a gastric wall abscess. Abdominal pain and fever persisted despite conservative management using antibiotic therapy, and we performed endoscopic ultrasound-guided drainage. The aspirated fluid was purulent with abnormally high levels of pancreatic enzymes. These findings indicated a rare case of gastric wall abscess that originated from gastric ectopic pancreas. Symptoms improved with the treatment, and post-discharge contrast-enhanced CT revealed disappearance of the cystic lesion and partial reduction of the submucosal tumor-like lesion. This clinical course suggests that endoscopic ultrasound-guided drainage may be a safe and effective treatment for a gastric wall abscess that originated from the gastric ectopic pancreas.

A 63-year-old woman with a positive result on fecal occult blood testing underwent CS which revealed a submucosal tumor (approximately 5 cm) on the hepatic flexure of the transverse colon. Endoscopy and enema examination revealed a typical lipoma. However, the patient had no specific symptoms; therefore, she was followed up without any treatment. CS performed 42 months after the initial examination (again after a positive result on fecal occult blood testing) revealed an ulcer on the tumor surface, with the size reduced to approximately 1.5 cm. Biopsy could not establish a definitive diagnosis; therefore, considering the malignant nature of the tumor based on its morphology, we performed laparoscopic-assisted resection for diagnostic confirmation. Histopathological evaluation of the resected specimen revealed a lipoma. Tumor morphology changed significantly during the disease course. We report a rare case of a diagnostically challenging colorectal lipoma.

Precut is performed in patients with difficult transpapillary biliary cannulation and is regarded as a salvage procedure performed only by expert endoscopists. Recently, the efficacy of early precut was reported from Europe, and more recently, the utility of direct (namely “primary”) precut was reported from Asia (Korea and India). Precut is recognized as a highly skilled technique for trainees; however, in near future, its utility may lead to a major turning point based on the results of these studies. Due to its highly skilled technique, precut training under expert endoscopists during endoscopic retrograde cholangiopancreatography may be provided to trainees to achieve early selective biliary cannulation. However, the details about precut, including terminology and technique have not been established. Therefore, this study defined precut-related terminology and described the related trends, selection of devices, and technique in detail.

In recent years, cancer genomic medicine centered on comprehensive genomic profiling (CGP) has been widely practiced in the field of pancreatic cancer. EUS-guided tissue acquisition (EUS-TA) has played an important role in pancreatic cancer diagnosis, and recently, more tissue samples for CGP testing are required for EUS-TA.

To perform a CGP test, it is desirable to know the following: the differences between the CGP tests approved by insurance in Japan (the OncoguideTMNCC Oncopanel System (NCCOP) and the Foundation One CDx Cancer Genome Profile (F-One); the required analysis criteria; the needle selection method to meet these criteria as much as possible; and the target of puncture. In addition, it is important to understand both specimen collection and processing to increase the success rate of the CGP test. The field of cancer genomic medicine is expected to enter an era of increasing turbulence in the future, and endoscopists must respond flexibly to these changes.

Objectives: Delayed bleeding is a major adverse event in endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Some patients may experience rebleeding after successful hemostasis for delayed bleeding, yet the details of rebleeding remain unclear. We aimed to clarify the frequency and risk factors of rebleeding.

Methods: Among 11,452 patients who underwent ESD for EGC at 33 institutions in Japan between 2013 and 2016, we analyzed 489 patients showing delayed bleeding. The rate of rebleeding was investigated. Subsequently, 15 candidate variables were evaluated for their influence on the risk of rebleeding via logistic regression analysis.

Results: Rebleeding occurred in 11.2% (55/489) of the enrolled patients. Multivariate analysis revealed that warfarin [odds ratio (OR), 2.71; 95% confidence interval (CI), 1.26-5.84] and a resection size >40 mm (OR, 1.99; 95% CI, 1.08-3.67) were independent risk factors for rebleeding. In the analysis of themanagement of warfarin after index bleeding, only warfarin discontinuation (OR, 3.66; 95% CI, 1.37-9.78) was significantly associated with rebleeding in comparison with no use of warfarin. However, many rebleeding events (75.0%) occurred following the resumption of warfarin. The rebleeding rate during discontinuation status and that in taking warfarin (continuation or resumption) were 6.1% and 20.0%, respectively.

Conclusions: Rebleeding was not a rare event in patients experiencing delayed bleeding after ESD for EGC. In addition to having a resection size >40mm, warfarin usage placed patients at high risk for rebleeding, especially at the timing of its resumption following discontinuation as well as its continuation.