Pathological examination is necessary for the definitive diagnosis of amyloids. Additionally, biopsies from the gastrointestinal tract are subjected to pathological examination because amyloids are deposited in the gastrointestinal tract. Therefore, it is necessary to study the endoscopic and histological characteristics of patients with systemic amyloidosis and gastrointestinal lesions. Although gastrointestinal manifestations are usually nonspecific, the histopathologic pattern of amyloid deposition is associated with clinical and endoscopic features; AL, Aβ2M, and ATTR amyloids are deposited in the submucosal layer. Conversely, AA amyloid is deposited in the superficial layers of the mucosa. Consequently, AL amyloidosis usually presents with constipation, mechanical obstruction, and chronic intestinal obstruction, whereas AA amyloidosis presents with diarrhea and malabsorption. Biopsy specimens should be considered for collection from the duodenum, in which a delicate granular appearance and polypoid protrusions may occur, and a positive biopsy ratio for diagnosing amyloidosis is high. The gastrointestinal manifestations of amyloidosis are primarily refractory and affect quality of life and patient survival. Because amyloidosis has a poor prognosis, early diagnosis and treatment are necessary, and endoscopists are important in the diagnosis.

Gastric neuroendocrine tumor (G-NET) is a tumor with low malignancy and good prognosis. Gastric neuroendocrine carcinoma (G-NEC), a rare subtype of gastric cancer (0.2-0.6% of all gastric cancers), is characterized by rapid growth, frequent lymphovascular invasion, and a high metastasis rate, with aggressive biological behavior. Most G-NEC cases are diagnosed at advanced stages with lymph node or distant metastases, and the prognosis of G-NEC is worse than that of common-type gastric adenocarcinomas. Thus, G-NETs and G-NECs have completely different characteristics and should be differentiated endoscopically. In white-light endoscopy, G-NET presented as elevated lesions, with “reddish color,” “dilated vessels,” “SMT-like marginal elevation,” and “central depression.” G-NEC showed as depressed or ulcerative lesions, with “SMT-like marginal elevation,” “adherent white coat,” and “ulceration with a distinct border.” On magnifying narrow-band imaging, “absent microsurface (MS) pattern plus irregular microvascular (MV) pattern” in the central depression and “absent MS pattern plus disrupted irregular MV” were characteristic findings of G-NET and G-NEC, respectively. These endoscopic features should be considered to increase the index of suspicion and correctly diagnose G-NETs and G-NECs through the pathological examination of biopsy specimens.

Background: Recently, the incidence of superficial non-ampullary duodenal epithelial tumors (SNADETs) has been increasing in Japan. The detection rate of SNADETs and associated factors were investigated in Japanese health checkup examinees who underwent EGD.

Methods: The overall detection rate of SNADETs was calculated for 13,138 patients who underwent EGD during a five-year observation period. Moreover, an objective index, the SNADET detection rate (SDR), was defined as the ratio of detected SNADET cases to the number of EGD cases for each endoscopist. The clinical factors associated with the SDR were analyzed and statistically extracted.

Results: The overall detection rate of SNADETs was 0.21% (27/13,138 cases), which was higher than that previously reported in Japan (0.03-0.04%). SDR varied depending on the endoscopist (SDR range; 0.29-5.95‰, median; 1.39‰). Statistical analysis demonstrated that endoscopists with a high SDR detected significantly more SNADETs in the inferior duodenal angulus and horizontal part of the duodenum than other endoscopists.

Conclusion: Thorough duodenal observation, including the inferior duodenal angulus and horizontal part of the duodenum, during upper gastrointestinal screening in health checkups may improve the overall detection rate of SNADETs.

In 2011, an 83-year-old woman was diagnosed with Sjögren syndrome and underwent anticoagulation therapy for atrial fibrillation. Because of anemia, she was referred to our Department of Gastroenterology in January 2023 for further examination. Upper gastrointestinal endoscopy revealed a 10-mm 0-Ⅱc-like faded lesion in the greater curvature of the lower gastric body; therefore, biopsy was performed. The following day, the patient revisited the hospital because of melena. Endoscopic hemostasis was performed to stop bleeding. Immunohistochemistry revealed transthyretin amyloidosis, suggesting that tissue fragility due to amyloid deposition and anticoagulant therapy caused bleeding.

The patient was a 28-year-old man who underwent 24Fr gastrostomy and tracheostomy for amyotrophic lateral sclerosis and was hospitalized for acute cholangitis. Although CT and magnetic resonance cholangiopancreatography showed no bile duct stones, recurrent episodes persisted. Insertion of the therapeutic duodenoscope into the esophagus was unsuccessful. To address the recurrent cholangitis after laparoscopic cholecystectomy for cholecystolithiasis, a 5Fr biliary stent was placed via gastrostomy using an ultrathin endoscope. Despite regular stent replacement, acute cholangitis due to migrated biliary stent recurred. We planned stomal dilation, which successfully allowed the insertion of the duodenoscope. After stent removal, sphincterotomy and removal of tiny bile stones were performed without any complications. The patient showed no recurrence after treatment.

We encountered a case of cryptosporidiosis in a man in his 20s with no medical history who developed right lower abdominal pain, fever, and diarrhea. Although the cause was unknown in the stool examination, Cryptosporidium protozoa were suspected in the ileum and colon biopsy tissue examination. The patient was diagnosed with cryptosporidiosis caused by Cryptosporidium parvum by polymerase chain reaction examination of the biopsy tissue. In cases in which abdominal symptoms, such as diarrhea, are severe and long-lasting for mere viral enteritis, it is important to conduct a detailed interview about the patientʼs life history, remember parasitic diseases, including this case, perform additional stool tests (acid-fast bacteria staining and sucrose centrifugal flotation method), and conduct thorough examinations, such as endoscopy, together with a pathologist.

An 86-year-old man with a history of colorectal cancer surgery underwent a CS that identified a 10-mm superficial elevated lesion in the ascending colon. The lesion showed findings consistent with an open type Ⅱ pit pattern, and histopathological biopsy confirmed the diagnosis of a sessile serrated lesion (SSL). At the initial examination, multiple adenomatous polyps were detected and resected endoscopically, but the SSL was kept under surveillance. During the first follow-up at two years and one month, no significant morphological changes were observed in the SSL. However, at four years and three months, a shallow central depression was noted, raising suspicion for progression. Biopsy at this time revealed a highly differentiated adenocarcinoma, and endoscopic resection was performed. Histopathological evaluation showed well-differentiated adenocarcinoma with invasion into the submucosal layer (2,000 μm) and positive lymphatic invasion. Subsequent genetic analysis identified a BRAF mutation.

Here, we report this interesting case to speculate the growth and progression of SSL.

Colorectal ESD of large protruding lesions requires advanced techniques. The complexity of large protruding lesions increases with tumor size, as well as the possibility of severe fibrosis and the muscle retracting sign. To address these issues, in addition to the basic tunneling technique, a double tunneling method was used for more difficult cases. In this method, tunnels are created on both sides and dissected if severe fibrosis or a muscle retraction area is observed within the tunnel, thereby improving safety and allowing en bloc resection. Among large protruding lesions, particularly those larger than 4 cm in diameter, there is an increased risk of severe fibrosis and a muscle retracting sign, as well as the possibility of deeper tumor invasion. Therefore, it is important to select a treatment strategy based on a comprehensive assessment of the lesion site, patient background, and pre-operative diagnosis.

Objectives: Despite recent advances in endoscopic equipment and diagnostic techniques, early detection of ulcerative colitis-associated neoplasia (UCAN) remains difficult because of the complex background of the inflamed mucosa of ulcerative colitis and the morphologic diversity of the lesions. We aimed to describe the main diagnostic patterns for UCAN in our cohort, including lateral extension surrounding flat lesions.

Methods: Sixty-three lesions in 61 patients with flat-type dysplasia that were imaged with dye chromoendoscopy (DCE) were included in this analysis. These DCE images were analyzed to clarify the dye-chromoendoscopic imaging characteristics of flat dysplasia, and the lesions were broadly classified into dysplastic and nondysplastic mucosal patterns.

Results: Dysplastic mucosal patterns were classified into two types: small round patterns with round to roundish structures, and mesh patterns with intricate mesh-like structures. Lesions with a nondysplastic mucosal pattern were divided into two major types: a ripple-like type and a gyrus-like type. Of note, 35 lesions (55.6%) had a small round pattern, and 51 lesions (80.9%) had some type of mesh pattern. About 70% of lesions with small round patterns and 49% of lesions with mesh patterns were diagnosed as high-grade dysplasia or carcinoma, while about 30% of lesions with small round patterns and 51% of lesions with mesh patterns were diagnosed as low-grade dysplasia.

Conclusion: When a characteristic mucosal pattern, such as a small round or mesh pattern, is found by DCE, the possibility of UCAN should be considered.