Autoimmune pancreatitis can be confirmed with gastroscopy.

Abstract

Autoimmune Pancreatitis Can Be Confirmed with Gastroscopy Terumi Kamisawa, Masami Yoshiike, Hitoshi Nakajima, Atsutake Okamoto Background: Autoimmune pancreatitis (AIP) is a unique clinical entity characterized by diffuse enlargement of the pancreas, diffusely irregular narrowing of the pancreatic duct, increased levels of serum gammaglobulin, presence of autoantibodies, lymphoplasmacytic infiltration with fibrosis, and favorable response to steroid therapy. Immunohistochemically, infiltration of abundant IgG4-positive plasma cells was observed in the pancreas, bile duct, and gallbladder of patients with AIP, but in none of controls. AIP occurs predominantly in elderly males and frequently presents as obstructive jaundice. This is also typical of pancreatic carcinoma. As most patients with AIP respond to oral steroid therapy, accurate diagnosis of AIP can avoid unnecessary laparotomy or pancreatic resection. However, histopathological approaches to the pancreas are sometimes difficult. Aims: This study aims to investigate diagnostic usefulness of gastroscopy for AIP. Methods: We immunohistochemically examined the stomach of 13 patients with AIP (6 pancreatoduodenectomies and 7 endoscopic biopsy specimens) and 20 controls using anti-IgG4 antibody. Endoscopic findings of the stomach of 10 patients with AIP were examined. Results: Infiltration of IgG4positive plasma cells detected in the gastric lamina propria was severe (>30/high power field: hpf) in 3 patients, moderate (30-11/hpf) in 5 patients, mild (10-5/hpf) in 4 patients, and only a few (<5/hpf) in 1 patient with AIP. Concentration of IgG4-positive plasma cells varied from site to site, but the entire stomach may be affected. Only a few IgG4-positive plasma cells infiltrated the gastric mucosa in controls. Abundant IgG4-positive plasma cells infiltrating the gastric mucosa almost disappeared in the gastroscopic biopsy specimens after steroid therapy. Gastroscopic findings were typically unremarkable, although the gastric mucosa may appear slightly thickened without clear vascular patterns in parts. Conclusions: Although clinical and endoscopic findings are non-specific, accumulations of IgG4-positive plasma cells in the gastric mucosamight represent part of a systemic IgG4-related autoimmune disease (IgG4-related gastritis). Autoimmune pancreatitis could be confirmed by demonstrating infiltration of numerous IgG4-positive plasma cells in the gastricmucosa on gastroscopic biopsy.