Search

Reports of Helicobacter pylori (Hp)-naïve gastric neoplasm (HpNGN) cases have been rapidly increasing due to the recent increase in the Hp-naïve population in Japan. Most HpNGNs exhibit the gastric immunophenotype and a low malignant potential regardless of histological type. Especially, foveolar-type gastric adenoma (FGA) and intestinal-type gastric dysplasia (IGD) rarely progress to invasive carcinoma. FGA is a foveolar epithelial neoplasm that occurs in the fundic gland (oxyntic gland) mucosa and is classified as the flat type or raspberry type (FGA-RA). The flat type is a large, whitish flatly elevated lesion while FGA-RA is a small reddish polyp. Genomically, the flat type is characterized by APC and KRAS gene mutations and FGA-RA by a common single nucleotide variant in the KLF4 gene. This KLF4 single-nucleotide variant reportedly induces gastric foveolar epithelial tumorigenesis and activates both cell proliferation and apoptosis, leading to its slow-growing nature. IGD consists of an intestinalized epithelial dysplasia that develops in the pyloric gland mucosa, characterized as a superficial depressed lesion surrounded by raised mucosa showing a gastritis-like appearance. Immunohistochemically, it exhibits an intestinal or gastrointestinal phenotype and, frequently, p53 overexpression. Thus, IGD shows unique characteristics in HpNGNs and a potential multistep tumorigenic process., (© 2024 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

Along with a recent remarkable decrease in Helicobacter pylori-infected individuals, reports of gastric neoplasms such as sporadic foveolar-type gastric adenoma (FGA) in H. pylori-naive patients have been increasing. This tumor, with its raspberry-like appearance, is common in H. pylori-naive gastric mucosa. The current study investigated the genomic features of sporadic FGA. Fresh-frozen sporadic FGA tissue samples from H. pylori-naive patients were subjected to whole genome analysis using a next-generation sequencer. Proliferation ability and apoptotic profiles of human gastric epithelial cells, along with plasmid transfection of candidate variants, were examined. A mean of 6.65 × 10 8 total reads were obtained for each sample. Common genetic abnormalities in well-known proliferation driver genes of conventional gastric dysplasia/cancer were not found. However, a common single-nucleotide variation (SNV) was noted within the DNA-binding domain of the tumor suppressor gene KLF4. This novel SNV was located in the zinc finger 2 region. Additional experiments showed that it significantly suppressed proliferation of gastric epithelial cells compared with wild-type KLF4 plasmid-transfected cells, although suppression was reduced in early apoptotic phase-related genes. A novel SNV in the KLF4 zinc finger 2 region was commonly found in sporadic FGA tissue samples, which may explain the slow-growing properties of this neoplasm., (Copyright © 2022 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Sporadic foveolar-type gastric adenoma (FGA) has been described as an extremely rare polyp that is whitish and flatly elevated. However, we recently found that sporadic FGA with a raspberry-like appearance (FGA-RA) is not rare in Helicobacter pylori (H. pylori)-naïve gastric mucosa. We endoscopically or surgically treated 647 patients with gastric epithelial neoplasms in the last 5 years, with 7.7% (50/647) being H. pylori-naïve. Among these, 43 FGA-RAs were diagnosed based on histologic and endoscopic features in 34 patients, who were all enrolled in this retrospective study. All lesions were observed by white-light endoscopy (WLE) and narrow-band imaging with magnification endoscopy (NBIME). We subsequently analyzed their endoscopic and microscopic features and patient characteristics. The patients were 22 males and 12 females aged 57±23 years (mean±2SD). WLE showed raspberry-like small polyps mimicking gastric hyperplastic polyps in the oxyntic gastric compartment (body/fundus). Multiple growths were confirmed in 20.6% (7/34) of the patients. NBIME revealed irregularly shaped papillary/gyrus-like microstructures with abnormal capillaries. Histologically, all lesions were intraepithelial neoplasms, and most of lesions (62.8%, 27/43) exhibited low-grade dysplasia. Immunohistochemically, neoplastic cells featured strong and diffuse MUC5AC expression, negative or very low MUC6 expression, and negative MUC2/CD10 expression. They also showed Ki-67 hyperexpression with a mean labeling index of 59.4±48.7%. The coexistence of fundic gland polyps in the background mucosa was significantly higher in multiple FGA-RA cases than in solitary cases (100% vs. 55.5%, P< 0.05). FGA-RA is a newly suggested histologic variant of sporadic FGA whose occurrence is not rare in daily endoscopic practice., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background and Study Aims: Magnification endoscopy with narrow-band imaging (NBIME) and NBIME with acetic acid enhancement (A-NBIME) visualize the capillary and microstructure patterns of the gastric mucosal surface, respectively. This study aimed to compare the diagnostic accuracy and interobserver agreement for white-light endoscopy (WLE), NBIME, and A-NBIME in the different histologic types of gastric mucosal neoplasm., Patients and Methods: Consecutive gastric neoplasms (n = 220; 49 adenomas, 144 differentiated adenocarcinomas, and 27 undifferentiated adenocarcinomas) were photographed with WLE, NBIME, and A-NBIME. Macroscopic patterns using WLE, capillary patterns using NBIME, and microstructure patterns using A-NBIME were respectively classified into type M1/M2/M3, type C1/C2/C3/C4, and type S1/S2/S3, as the indicators of adenoma, differentiated adenocarcinoma, and undifferentiated adenocarcinoma (Type C4, unevaluable because of capillary invisibility), according to the previously reported classifications. Endoscopic images were independently reviewed by three experts and three non-experts. Diagnostic accuracy and interobserver diagnostic agreement were compared among the modalities., Results: Kappa values (95 % confidence interval [CI]) for WLE, NBIME, and A-NBIME diagnosis were 0.36 (0.33 - 0.39), 0.58 (0.54 - 0.61), and 0.62 (0.55 - 0.68) for experts and 0.31 (0.29 - 0.33), 0.36 (0.34 - 0.38), and 0.52 (0.48 - 0.56) for non-experts, showing good reproducibility of A-NBIME diagnosis regardless of proficiency. All experts and non-experts diagnosed the histologic types statistically more accurately with A-NBIME than with WLE and NBIME (P < 0.05). Overall the "experts-agreed" diagnostic accuracy (95 %CI) was 75.5 % (70.0 - 81.0) for WLE vs. 74.1 % (67.6 - 80.6) for NBIME vs. 90.5 % (86.7 - 94.1) for A-NBIME (P < 0.05). WLE and NBIME were insufficient to predict the diagnosis of adenomas and undifferentiated adenocarcinomas., Conclusion: A-NBIME showed statistically significantly higher diagnostic accuracy for gastric mucosal neoplasms, with good reproducibility, compared with WLE and NBIME, which provided similar lower accuracy., (© Georg Thieme Verlag KG Stuttgart · New York.)