Gastroenteropancreatic Neuroendocrine Tumors (GEP/NETs) are rare neoplasms originating from the diffuse neuroendocrine system, involving 15 types of highly differentiated ectodermal cells located in the gastrointestinal tract and pancreas. The most common location of GEP/NETs is in the appendix (62% of cases), but they may also be found in small intestine (27%), lung (15%), undefined primary locations with hepatic metastases (12%) and other organs (3%)[1
]. GEP/NETs secrete peptides and neuroamines that cause distinct clinical syndromes, including carcinoid syndrome. Many tumors are, however, clinically silent until late presentation associated with mass effects. The current WHO classification categorizes GEP/NETs into: (1) well-differentiated neuroendocrine tumor; (2) low-grade malignant carcinoma; (3) high-grade malignant carcinoma and (4) mixed tumor: adenocarcinoma/neuroendocrine carcinoma[2
]. At present 14 terms are used to define tumors with mixed exocrine-endocrine features. Volante et al[3
] proposed classification based on the extension of each component and structural features of the NE component. Three separate patterns can be distinguished i.e. (1) NE tumors with focal non-NE component occupying less than 30% of the tumor, (2) mixed exocrine-endocrine carcinomas (NE or non-NE cells > 30%) and (3) non-NE carcinoma with NE component (< 30%). The type of tumor influences the prognosis, which improves with increasing contribution of NE component[3
]. About 50% of GEP/NETs are carcinoids found by chance during laparotomy or as hepatic metastases.
Carcinoids involving the papilla of Vater are rare lesions, accounting for 0.35% of all gastrointestinal carcinoids. So far, only 110 cases have been reported in the literature, mostly as individual case reports[4
]. These tumors are predominantly found on ERCP in patients with obstructive jaundice or acute biliary pancreatitis. In the presented case the tumor histologically was a mixed carcinoid-adenocarcinoma neoplasm (type IV). The concurrence of carcinoid with adenocarcinoma is an unusual phenomenon in the gastrointestinal tract, that has been reported in the oesophagus, stomach, small intestine, appendix, colon and rectum[5-7
]. To our knowledge, this is the seventh report of this rare neoplastic association in the duodenal periampullary region.