Fistulating Intraductal Papillary Mucinous Neoplasms (IPMNs): Case Series and Discussion of a Rare Complication

Background: Intraductal papillary mucinous neoplasm (IPMN) is a mucin-producing pancreatic tumor with variable malignant potential. While most are asymptomatic and indolent, a subset progress to invasive carcinoma or cause local complications such as pancreatitis. Spontaneous fistulation into adjacent organs is an increasingly recognized phenomenon with impact on prognosis and management. The incidence of fistulation in IPMN in the reported literature is 1.9-6.6%. The most common sites are the stomach, duodenum and bile duct. Reported outcomes are poor, with a median survival of approximately 16 months. Methods: We describe four patients with IPMN complicated by fistula, confirmed by endoscopic or histopathological evaluation with CT and MRI images and discuss the available literature of fistulating IPMN. Results: Fistulation occurred at the common bile duct, stomach, duodenum and duodeno-jejunal junction. Two of four patients passed away at 4.8 and 24.8 months from detection of fistula. Histology revealed high-grade dysplasia or invasive carcinoma in most patients, highlighting the aggressive nature of IPMNs complicated by fistulae. Conclusions: Our findings reinforce the importance of recognizing fistula formation as a marker of aggressive disease in IPMN. Although surgical resection remains the treatment of choice in suitable candidates, the rarity of this entity means that standardized management guidelines are lacking.