A case of chronic cholangitis caused by calculi with foreign matter mimicking perihilar cholangiocarcinoma.

Perihilar cholangiocarcinoma (pCCA), originating from the second-order bile ducts and extending to the cystic duct insertion, is the most common cholangiocarcinoma subtype and carries a dismal prognosis. It is typically characterized by obstructive jaundice and elevated serum carbohydrate antigen 19-9 (CA19-9); however, these features significantly overlap with those of benign biliary diseases. While endoscopic retrograde cholangiopancreatography-guided tissue sampling is crucial for diagnosis, its sensitivity remains suboptimal. Consequently, up to 15% of preoperatively suspected pCCA cases are confirmed as benign strictures postoperatively. Given the close association between choledocholithiasis and pCCA, distinguishing malignancy from stone-induced inflammatory disease remains a significant diagnostic challenge. Herein, we report a rare case of chronic cholangitis mimicking pCCA, ultimately attributed to calculi containing a retained foreign body.