Endoscopic and histological features of Helicobacter pylori‐negative differentiated gastric adenocarcinoma arising in the antrum

BACKGROUND AND AIM: With the increasing prevalence of persons without Helicobacter pylori (HP) infection, cases of HP‐negative gastric cancer are increasing. Although rare, cases of differentiated adenocarcinoma of the antrum have been reported in HP‐negative patients. We collected cases with such lesions and investigated their endoscopic and histological features. METHODS: Of 1965 consecutive patients with early gastric cancer who underwent endoscopic resection between January 2009 and December 2017, we extracted 9 cases of HP‐negative differentiated adenocarcinoma located in the antrum (HPN‐DAA). The clinical data, endoscopic findings, and histopathological findings were reviewed. RESULTS: Of the nine patients with HPN‐DAA, seven were male, and the median age was 53.8 years. The tumor arose from the pyloric gland mucosa in all cases. According to the endoscopic findings, the lesions were flat‐elevated or depressed, mimicking varioliform gastritis. Magnifying endoscopy with narrow‐band imaging showed the absence of a clear demarcation line or an irregular microvessel/surface pattern. As for the histopathological findings, eight of the nine lesions were diagnosed as high‐grade dysplasia/intraepithelial neoplasia, while the remaining case was diagnosed as tubular adenocarcinoma with submucosal infiltration. The findings of immunohistochemistry confirmed that three cases were of the intestinal mucin phenotype and six were of the mixed gastric and intestinal mucin phenotype. CONCLUSION: HPN‐DAA is a very rarely occurring cancer that had never been recognized earlier. They belong to the new category of HP‐negative cancers, and there seems to be a certain number of such cases.