# Pancreaticobiliary Fistula Caused by Intraductal Papillary Mucinous Adenoma Requiring Pancreaticoduodenectomy

## TL;DR

A rare case of a pancreatic tumor causing a fistula between the pancreas and bile duct is described, requiring surgery after drainage failed.

## Contribution

This case highlights a rare pancreaticobiliary fistula caused by IPMA, not IPMC, and the need for early surgical intervention.

## Key findings

- Pancreaticobiliary fistula caused by IPMA was successfully treated with SSPPD after ENBD failed.
- Histopathology confirmed the tumor as intestinal-type IPMA.
- Fistulas can occur in IPMA without IPMC, emphasizing the importance of early surgical evaluation.

## Abstract

Fistula formation from the intraductal papillary mucinous neoplasm (IPMN) into neighboring organs is rare. We describe a case of pancreaticobiliary fistula with obstructive jaundice caused by an intraductal papillary mucinous adenoma (IPMA).

An 81-year-old man who was incidentally diagnosed with IPMN 11 years previously based on follow-up CT performed after nephrectomy for renal cell carcinoma. Gradual dilation of the main pancreatic duct was observed over time, confirming the high-risk stigmata for which surgery was recommended; however, the patient declined and was managed under surveillance. At a routine diabetes clinic visit, blood tests revealed inflammatory markers and hepatobiliary enzymes. Contrast-enhanced CT revealed a pancreatic head IPMN in extensive contact with the common bile duct with partial communication. Endoscopic nasobiliary drainage (ENBD) was performed, but resolution of jaundice proved difficult due to obstruction by mucin; therefore, we performed a subtotal stomach-preserving pancreaticoduodenectomy (SSPPD). Severe inflammation was observed around the pancreas and bile ducts at the surgical site. The postoperative course was favorable, and the patient was discharged on the POD 16. The histopathological diagnosis was intestinal-type IPMA.

Most reported IPMN-related organ fistulas result from direct invasion by IPMC. By contrast, IPMA-related fistulation is exceedingly rare. We present an intestinal-type IPMA complicated by pancreaticobiliary fistula in which mucin defeated ENBD, necessitating SSPPD, and the patient had an uneventful recovery. This case shows that fistulation can occur even without IPMC and that early surgery should be considered in IPMN patients with pancreatobiliary fistula.