A Composite Tumor of the Ampulla of Vater: Signet-ring Cell and Neuroendocrine Carcinoma: A Case Report

ABSTRACT

Most tumors affecting Vater's ampulla are adenocarcinomas. Other histological variants or mixed forms are less frequent, even rare. We treated a rare case of composite signet-ring cell carcinoma and well differentiated neuroendocrine carcinoma of the ampulla of Vater in a 72-year-old Korean man with abdominal discomfort and jaundice for two weeks. Computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP) revealed a 2 cm protruding mass with an abrupt narrowing of the distal common bile duct. Pancreaticoduodenectomy was performed. An ill-defined nodular 2 cm mass in the ampulla of Vater invaded the entire duodenal wall and pancreatic parenchyma with duct dilatation of the remaining common bile duct and pancreatic duct. Two out of twenty regional lymph nodes were positive for metastases. Histopathologically, the tumor was composed of mucinous adenocarcinoma with predominant signet-ring cell components (80%) and well-differentiated neuroendocrine carcinoma (20%). There were intermingled and transitional areas between both elements as well as amphicrine tumor cells with dual differentiation. By Immunohistochemistry, the adenocarcinoma with signet-ring cells was positive for CK7 and CEA and the neuroendocrine carcinoma was diffusely positive for CK7, synaptophysin and chromogranin but negative for insulin and CEA. Of the two metastatic peripancreatic lymph nodes, one was a neuroendocrine carcinoma and the other was an adenocarcinoma. The postoperative course was uneventful. The patient refused adjuvant chemotherapy and was discharged to home 13 days later. The patient died of multiple liver metastases and carcinomatosis 11 months after surgery.