Anatomic Pathology / VERY WELL-DIFFERENTIATED GASTRIC CANCER Usefulness of p53 and Ki-67 Immunohistochemical Analysis for Preoperative Diagnosis of Extremely

histochemistry A b s t r a c t Of 987 cases of gastric adenocarcinoma seen at Nagoya University School of Medicine, we found 6 rare, extremely well-differentiated advanced gastric adenocarcinomas that could not be diagnosed as malignant tumors with only H&E staining, even with repeated biopsies under preoperative endoscopy. The aim of this study was to determine whether an immunohistochemical method using p53 and Ki-67 antibody would be helpful for preoperative pathologic diagnosis. The cancer control cases were 16 cases of ordinary well-differentiated advanced gastric adenocarcinoma, while the gastritis control cases were 22 cases of Helicobacter pylori–positive chroni