Neuroendocrine Carcinoma with an Adenocarcinoma Component onthe Ampulla of Vater Causing Acute Pancreatitis: A Case Report

We encountered a rare case in which a 14 mm ampullary tumor had both components of neuroendocrine carcinoma and adenocarcinoma, which caused acute pancreatitis. A Sixty-one-year-old woman was referred to our hospital for evaluation and treatment of pancreatitis due to an unknown cause. After various imaging examinations, the cause of pancreatitis was found to be a duodenal papillary tumor. We performed endoscopic retrograde pancreatic duct drainage by inserting a drainage tube; subsequently, her abdominal pain was relieved, and the pancreatic enzyme levels normalized. As the pathological findings showed poorly differentiated neuroendocrine carcinoma, pancreaticoduodenectomy was performed. As liver and lymph node metastases were found 3 months postoperatively, she underwent chemotherapy. Although she achieved complete remission once, metastases relapsed and she died of progressive disease 28 months postoperatively. Histological examination showed that the tumor comprised two elements: the main component (99.5%) was neuroendocrine carcinoma, and the minor component was adenocarcinoma. The adenocarcinoma component was observed only in the mucosal layer, whereas the neuroendocrine component invaded the submucosa or deeper layer. It is speculated that adenocarcinoma had arisen first from the epithelium, and then it acquired neuroendocrine differentiation capabilities during growth. Although some reports have proposed that neuroendocrine components have more aggressive features than adenocarcinoma components, it is still unclear whether the neuroendocrine or adenocarcinoma component is the main driving force of disease progression. Neuroendocrine carcinoma with an adenocarcinoma component is highly aggressive and associated with a high risk for distant metastasis and a poor prognosis, as in the present case.