Adult gastric teratoma associated with gastric cancer in a gastric diverticulum

Division of Hepato-Biliary Pancreatic Surgery, Tohoku University Graduate School of Medicine A 53-year-old man was seen in our hospital for examination of a tumor in the hepatic left lobe. Upper gatrointestinal endoscopy detected a type-3 tumor with deep ulceration in the anterior wall of the upper gastric corpus. Biopsy of the tumor yielded a diagnosis of moderately differentiated adenocarcinoma. Abdominal enhanced CT revealed a tunicate tumor in the small omentum, connecting to the gastric wall via gastric cancer. The tumor had fatty tissue, cystic lesions and fine calcification on diagnostic clinical imaging. We diagnosed the tumor in the small omentum as gastric teratoma. Based on the diagnosis of gastric cancer and gastric teratoma, we performed total gastrectomy and splenectomy. Pathological findings showed gastric cancer in a gastric true diverticulum and a mature gastric teratoma with no malignancy. The gastric diverticulum had resulted from traction of the exogastric teratoma. Both gastric teratoma in adults and gastric cancer in gastric diverticula are rare. To the best of authors' knowledge, gastric teratoma associated with gastric cancer in a gastric diverticulum has not been reported previously.