Biliopancreatic fistula associated with intraductal papillary-mucinous pancreatic cancer: institutional experience and review of the literature.

Intraductal papillary-mucinous tumour is clinicopathologically characterized by papillary growth and mucin production within the pancreatic duct system. The category includes a wide range of dysplasia, ranging from adenoma to carcinoma, the latter designated as intraductal papillary-mucinous cancer. In general, the tumor renders a favorable prognosis after complete resection. However, intraductal papillary-mucinous tumor with overt invasion outside the gland has been reported to have a poor prognosis, as is the case with the usual type of duct cell cancer of the pancreas. We experienced two cases of intraductal papillary-mucinous cancer with obstructive jaundice due to impaction of thick mucus protruding from the pancreas via a "spontaneous" biliopancreatic fistula. Preoperative examinations of both patients showed a large intraductal papillary-mucinous tumor in the head of the pancreas with fistula formation between the intrapancreatic portion of the common bile duct and the main pancreatic duct. Histopathological investigation of the two resected specimens suggested that the fistula may not have developed from invasion by papillary or tubular adenocarcinoma, but from compression and destruction of the intercalating tissues by abundant mucinous secretion. The first patient died of peritoneal carcinomatosis with clinicopathologic features of pseudomyxoma peritonei 6 years after surgery. The second patient is alive and has been well for 2 years postoperatively. Review of the world literature showed that half of the patients with intraductal papillary-mucinous cancer plus biliopancreatic fistula had no stromal invasion around the fistula, indicating that the fistula might have been caused by mechanical pressure. However, the other half of the cases did have stromal invasion around the fistula. Two-thirds of these cases, including our own patients, had foci of mucinous carcinoma in the stroma around the fistulization, implying that mucinous lakes in the stroma may have served as part of the "waterway" from the pancreatic duct to the bile duct, assisted by increased pressure by mucus production. Since intraductal papillary-mucinous cancer with biliopancreatic fistula has a comparatively favorable prognosis, surgical resection should be considered.