Gastric collision tumor of adenocarcinoma and epstein-barr virus-related carcinoma—a case report—

Abstract

A 73-year-old man visited our hospital with the complaint of black stools that had started 1 month ago. Upper gastrointestinal endoscopy revealed 2 type 1 tumors in the upper part of the lesser curvature and in the posterior wall of the gastric body and 1 type 0-IIc lesion in the antrum. Examination of the biopsy specimens of all 3 tumors revealed adenocarcinoma. Total gastrectomy and splenectomy with D2 lymph node dissection and Roux-en-Y esophagojejunostomy were performed. Histopathological examination revealed that the tumor in the posterior wall of the body consisted of 2 different parts : poorly differentiated and papillary adenocarcinomas. Because the 2 components had a clear border without transition, this tumor was thought to be a collision cancer. Moreover, because the poorly differentiated adenocarcinoma showed extensive lymphocyte infiltration, we performed Epstein-Barr virus (EBV) encoded small RNA (EBER-1) in situ hybridization. We found that the poorly differentiated adenocarcinoma was EBV-positive and the papillary adenocarcinoma was EBV-negative. The final diagnosis of this cancer was a collision tumor of papillary adenocarcinoma and EBV-related gastric carcinoma.