Malignant transformation of intraductal papillary neoplasm of the bile duct following non-standardized biliary-enteric drainage for hepatolithiasis: two case reports and literature review

Background Intraductal papillary neoplasm of the bile duct (IPNB) is a rare biliary epithelial neoplasm with malignant potential. It is characterized by intraductal papillary growth, variable mucin production, and a close association with chronic biliary inflammation. Case presentation We describe two patients with hepatolithiasis who developed IPNB after non-standardized biliary-enteric drainage without complete common bile duct transection. Both patients had long-term enterobiliary reflux and chronic cholangitis. Case 1 was diagnosed with intestinal-type IPNB with high-grade intraepithelial neoplasia and focal invasive mucinous adenocarcinoma and remained recurrence-free at 12 months despite a microscopically positive ductal margin (R1 resection). Case 2 had pancreatobiliary-type IPNB with moderately to poorly differentiated invasive adenocarcinoma and developed rapid postoperative peritoneal and distant metastases. Conclusion In these two patients with hepatolithiasis, non-standardized biliary-enteric drainage with a retained distal common bile duct and blind pouch was associated with long-term enterobiliary reflux, chronic cholangitis, and subsequent IPNB. These findings suggest a plausible contributing mechanism rather than an established causal relationship. When biliary-enteric reconstruction is otherwise indicated, surgical techniques that avoid a residual blind pouch and minimize enterobiliary reflux should be considered. Long-term surveillance may be warranted in patients with long-standing biliary inflammation after non-standardized drainage.