Case of a tumor comprising gastric cancer and duodenal neuroendocrine tumor

Abstract

The present report describes a rare case of a tumor composed of early gastric cancer and a duodenal neuroendocrine tumor (NET). A 78-year-old woman underwent esophagogastroduodenoscopy at a local institution for screening of the upper gastrointestinal tract which revealed a protruded tumor through the pyloric ring from the pyloric antrum. The tumor was too large to treat at the facility; consequently, she was referred to our hospital for further management. Esophagogastroduodenoscopy with tumor biopsy of the lesion revealed the diagnosis of early gastric cancer. Endoscopic submucosal dissection was performed with sufficient free margins in both vertical and horizontal directions. Histopathological findings showed NET confined to the submucosal layer and covered by well-differentiated adenocarcinoma. Immunohistochemical stainings showed that the two lesions existed continuously. While the possibility of a collision cancer was considered, it was suggested that the two lesions existed continuously. Finally, the tumor was diagnosed as gastric cancer composed of duodenal NET G1, with a lymphatic invasion of NET component.

Keywords: Gastric cancer; Endoscopic submucosal dissection; Neuroendocrine tumor; Composite- type tumor; Duodenum

Core tip: Although there are some reports of endoscopic resection performed to duodenal neuroendocrine tumor (NET), no reports have been published on the treatment of duodenal NET composed of early gastric cancer treated by endoscopic submucosal dissection (ESD). A 78-year-old woman underwent esophagogastroduodenoscopy and revealed a protruded tumor through the pyloric ring from the pyloric antrum. ESD was performed and finally the tumor was diagnosed as gastric cancer composed of duodenal NET G1, with a lymphatic invasion of NET component. We report the first case of early gastric cancer accompanied by duodenal NET, which was resected by ESD.