[Case of Mixed Neuroendocrine-Non-Neuroendocrine Neoplasm of the Papilla of Vater Metastasizing to the Lung after Resection].

A 79-year-old man visited a hospital for right upper abdominal pain and nausea. After conservative treatment for cholangitis and pancreatitis owing to a pancreatic head lesion, he was referred to our hospital for further evaluation and treatment of the lesion. He was diagnosed with pancreatic head cancer or carcinoma of papilla of Vater and underwent subtotal stomach- preserving pancreaticoduodenectomy. Postoperative histopathological examination revealed the coexistence of adenocarcinoma( 60%)and neuroendocrine carcinoma(40%)components, consistent with the diagnosis of mixed neuroendocrine- non-neuroendocrine neoplasm(MiNEN). In addition, regional lymph node metastasis of the adenocarcinoma component was found. Adjuvant chemotherapy was not administered because of a poor performance status. Lung metastasis occurred 13 months after surgery. Chemotherapy with S-1 was administered, and partial response was obtained 17 months after surgery. Herein, we report this rare case of MiNEN of the papilla of Vater with lung metastasis.