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Introduction: Since inflammatory cells, such as lymphocytes and plasma cells, normally inhabit the stomach, the border between normal and mild inflammation is difficult to visually determine using the updated Sydney system scale of gastritis. Additionally, eosinophils in the gastric mucosa must be counted to diagnose eosinophilic gastritis. We aimed to determine the normal number of inflammatory cells in patients with endoscopically normal mucosa and without Helicobacter pylori infections. Methods: We assessed patients aged 20–79 years, who had undergone upper gastrointestinal endoscopy at Kawasaki Medical School Hospital between January 2010 and December 2014. Inflammatory cells were counted in 1,000 μm2 fields of pyloric and fundic gland mucosal biopsy specimens. We finally included 325 (male, n = 141; female, n = 184; average age = 49.3 years) patients without inflammation who had H. pylori-negative endoscopic results and negative histological findings interpreted based on the updated Sydney System and the Kyoto classification of gastritis. Results: The average numbers of nucleated cells were 83.3 ± 14.2 and 65.4 ± 12.6/mm2 in the pyloric and fundic gland mucosae, respectively. Inflammatory cells were significantly more abundant in the pyloric mucosa than in the fundic gland mucosa (p < 0.05). Age and sex distribution did not significantly differ. Eosinophils were absent or scanty in the gastric mucosae of both glands in all patients. Conclusion: We determined the absolute values of inflammatory cells, including eosinophils, in normal mucosae of pyloric and fundic glands. These findings could be important in defining gastric mucosal inflammation, including eosinophilic gastritis diagnosis.

Background: Gastric adenocarcinoma of foveolar type (GA-FV) is a raspberry-shaped gastric cancer (RSGC) and garners much attention as H. pylori (Hp)-uninfected gastric cancer. However, the classification and clinicopathological and endoscopic features of RSGCs in Hp-uninfected patients are poorly defined. We designed a new histopathological classification of RSGC and compared them via endoscopic and clinicopathological characteristics. Summary: From 996 patients with early gastric cancers resected by endoscopy in our hospital, we studied 24 RSGC lesions from 21 (2.4%) Hp-uninfected patients. RSGCs were classified into 3 histological types as follows: GA-FV (n = 19), gastric adenocarcinoma of fundic gland type (GA-FG, n = 2), and gastric adenocarcinoma of fundic gland mucosa type (GA-FGM, n = 3). Most of the lesions were found at the greater curvature of the upper or middle third of the stomach. GA-FV lesions were homogeneously reddish and frequently accompanied with a whitish area around the tumor and an irregular microvascular (MV) pattern; these features were confirmed histopathologically by the presence of homogeneous neoplastic foveolar epithelium with foveolar hyperplasia around the tumors. GA-FG lesions might be heterogeneously reddish with a submucosal tumor shape and regular MV pattern; these were confirmed by the presence of covered or mixed nonneoplastic epithelium on deeper regions of tumors. GA-FGM lesions might be homogeneously reddish and occasionally had a submucosal tumor shape and irregular MV pattern; these were confirmed by the presence of homogeneous neoplastic foveolar epithelium on deeper regions of the tumors. Key Messages: RSGCs in Hp-uninfected patients are classified into 3 histopathological types. For accurate diagnosis of RSGCs, it may be necessary to fully understand endoscopic features of these lesions based on these histological characteristics and to take a precise biopsy.

Background: The characteristics of Helicobacter pylori (HP) infection-negative gastric cancer (HPINGC) have not been well documented because of the rareness. The aim of this study was to classify HPINGC endoscopically and clinicopathologically. Methods: This retrospective study included 1,741 early gastric cancer lesions and evaluated their HP infection status. Expression levels of MUC5AC, MUC6, MUC2, CD10, p53, MIB-1, pepsinogen-I, H+/K+ ATPase, chromogranin A, E-cadherin, and gastrin were evaluated in tumors by immunohistochemistry (IHC). Results: Among the analyzed lesions, 19 (1.1%) were diagnosed as HPINGC and classified into 6 types: undifferentiated (5 lesions), fundic gland (2 lesions), cardiac gland (1 lesion), pyloric gland (3 lesions), foveolar (5 lesions), and mixed (3 lesions) types. Undifferentiated lesions were of pale color, with unclear demarcation and decreased E-cadherin expression. Fundic-type lesions were tan to reddish in color, with submucosal tumor-like protrusions, and positive for pepsinogen-I and H+/K+ ATPase. The cardiac gland type was located in the gastroesophageal junction and was positive for MUC6 and pepsinogen-I. Pyloric gland-type lesions were of the same color as normal mucosa, with mild elevation and unclear demarcation, likely positive for CD10 and chromogranin A. Foveolar epithelial-type lesions were white and elevated, with defined demarcation, and contained MUC5AC-positive cells. Mixed-type lesions, showing various staining patterns in IHC, had both elevated and depressed shape and reddish color. Conclusion: Endoscopic observation and IHC were useful for classifying the characteristics of HPINGC, which may preserve the characteristics of its region of origin.

Aim: Helicobacter pylori-naïve gastric cancers(GCs) have not been well documented. We aimed to characterize early H. pylori-naïve GCs. Subjects and Methods: Of 666 patients with GC resected by endoscopic submucosal dissection, H. pylori-naïve patients were extracted according to the definition: no H. pylori eradication history, negative for serum H. pylori-antibody and current H. pylori-infection tests, and no gastric atrophy by pepsinogen (PG) test, endoscopy, and histology. Results: It was found that 16 GCs were H. pylori-naïve, and classified into undifferentiated and differentiated type adenocarcinoma. All 9 undifferentiated type GCs were pale, depressed, mucosal pure signet ring cell adenocarcinoma except one of them and 7 differentiated type GCs were classified into 3 fundic gland type GCs and 4 foveolar type GCs. All fundic gland type GCs positive for PG-1 were cardia small submucosal tumor (SMT)-like protrusions with dilated vessels on the surface. All 4 foveolar type GCs were composed of dysplastic clear cells resembling foveolar epithelium, negative for PG-1 but positive for mucin 6 (MUC6) and MUC5AC. Endoscopically, all were laterally spreading elevations with papillary or villous surface. Conclusions: H. pylori-naïve GCs were infrequent at 2.5%, and classified into 3 types: a small pale depression of signet ring cell adenocarcinoma, a small SMT-like protrusion of fundic gland type GC, and a large laterally spreading elevation of foveolar type GC.

Background/Aims: Matrix metalloproteinases (MMPs) are endopeptidases that degrade extracellular matrix and are involved in the pathogenesis of gastrointestinal ulcer and cancer along with tissue inhibitors of metalloproteinases (TIMPs). The purpose of this study is to examine their localization and functions in the normal stomach. Methods: We examined the localization of MMP-1, MMP-2, MMP-9 and TIMP-2 in normal human and rabbit stomachs by light- and electron-microscopic immunohistochemistry and Western blotting, and the enzymatic activities of MMP-2 and MMP-9 by gelatin zymography. Results: Immunohistochemistry revealed their localization in parietal cells, and surface and foveolar epithelial cells. Electron-microscopic immunohistochemistry of parietal cells showed immunolabeling of MMP-2 and TIMP-2 in the cisternae of the rough endoplasmic reticulum, and that of MMP-1 and MMP-9 in tubular structures in their cytoplasm. Western blotting revealed that the densities of MMP-2 and MMP-9 bands were higher for the fundic gland region than for the pyloric gland region. Gelatin zymography revealed that tissue extracts of the fundic gland region exhibited higher enzymatic activity of MMP-2 and MMP-9 than those of the pyloric gland region. Conclusion: Normal rabbit and human stomachs contain MMP-1, MMP-2, MMP-9, and TIMP-2 and these are mainly localized in, and synthesized by parietal cells.