Histological findings of the endoscopic biopsy specimen from the pylorus. HE staining shows a moderately differentiated gastric adenocarcinoma with abundant infiltration of lymphoplasmacytes and eosinophils in stroma (A). Immunostaining reveals Helicobacter pylori in gastric epithelial cells (B) or cancer cells (black arrow, C) or mesenchymal cells (red arrow, C), IgG4-positive (D) or IgG-positive plasma cells (E) in the cancer stroma. Original magnification × 400 (A, B and C), × 200 (D and E).