title: Malignant transformation of a gastric hyperplastic polyp in a context of Helicobacter pylori-negative autoimmune gastritis: a case report.
abstract: BACKGROUND
  Gastric foveolar hyperplastic polyps (GFHPs) are common findings in clinical practice. GFHPs commonly arise in a background of chronic atrophic gastritis, including autoimmune gastritis (type A gastritis), and have a potential risk of malignant transformation.
  
  
  METHODS
  In 2005, a 55-year-old Japanese woman underwent upper endoscopy at another hospital and was found to have a pedunculated polyp (10 mm in diameter) on the greater curvature of the lower gastric body. On biopsy, the polyp was diagnosed as a GFHP. Nine years later, the polyp had grown to 20 mm in diameter, and the biopsy specimen taken at this time showed tubular adenocarcinoma. On admission to our hospital, the serum Helicobacter Pylori (H. pylori) immunoglobulin G antibody and stool H. pylori antigen were both negative. Anti-gastric parietal cell antibody was positive, as was the anti-intrinsic factor antibody, and the fasting serum gastrin level was markedly increased. In 2014, en bloc resection of the pedunculated polyp was performed by endoscopic submucosal dissection. The final histological diagnosis was adenocarcinoma of the stomach with submucosal and lymphatic invasion. Subsequently, additional radical distal gastrectomy was performed. At the latest follow-up (12 months postoperatively), no recurrence was noted.
  
  
  CONCLUSIONS
  We here reported a rare case of malignant transformation of GFHP arising in a context of type A gastritis. To our knowledge, there are no previous reports on malignant transformation of GFHP with submucosal and lymphatic invasion arising in a background of type A gastritis in the English literature. Further, there is currently no effective treatment other than endoscopic or surgical treatment for such cases. Given the potential risk of malignant transformation due to hypergastrinemia, we consider that endoscopic treatment should be considered as a first-line therapy when a malignant growth is suspected.
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan. yken211@omiya.jichi.ac.jp.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamanaka
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Miyatani
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ishii
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Asabe
authors.affiliation: Department of Surgery, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Takada
authors.affiliation: Department of Pathology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nokubi
authors.affiliation: Department of Gastroenterology, Jichi Medical University, Saitama Medical Center, Saitama, 330-8503, Japan.
authors.forename: Hirosato
authors.initials: H
authors.lastname: Mashima
mesh_terms: D000230:Adenocarcinoma / Q000209:etiology / Q000473:pathology*; D018256:Adenomatous Polyps / Q000150:complications / Q000473:pathology*; D001327:Autoimmune Diseases / Q000150:complications / Q000473:pathology; D001706:Biopsy; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D005260:Female; D005757:Gastritis, Atrophic / Q000150:complications / Q000473:pathology; D005773:Gastroscopy; D016480:Helicobacter pylori; D006801:Humans; D006965:Hyperplasia / Q000150:complications; D008875:Middle Aged; D013270:Stomach / Q000473:pathology*; D013274:Stomach Neoplasms / Q000150:complications / Q000209:etiology / Q000473:pathology*
keywords: Autoimmune gastritis; Case report; Gastric carcinoma; Gastric hyperplastic foveolar polyp; Helicobacter pylori