Coexistence of gastric multiple neuroendocrine tumors with unusual morphological features and gastric signet-ring cell carcinoma.

The coexistence of signet-ring cell carcinoma and neuroendocrine tumors is very rare. We report a 57-year-old man who presented with a history of weight loss and nausea. Gastric mucosal biopsies obtained during gastrointestinal endoscopy revealed a gastric signet-ring cell carcinoma. The patient underwent a total gastrectomy with a standard D2 lymph node dissection. Ten individual tumors were detected in the resected specimen. Based on the histopathological and immunohistochemical findings, the final diagnosis was co-existing signet-ring cell carcinoma and neuroendocrine tumor. Spindle-shaped cells and extracytoplasmic mucin were noted in some tumor cells forming the neuroendocrine component. This case is a rare synchronous tumor because of its unusual neuroendocrine component.