Intrahepatic intraductal papillary neoplasm of the bile duct with low-grade dysplasia presenting as high biliary obstruction and hepatolithiasis: a case report

Abstract

Background Intraductal papillary neoplasm of the bile duct (IPNB) is an uncommon biliary epithelial neoplasm and an important precursor lesion of cholangiocarcinoma. The educational value of this case lies in demonstrating that IPNB may be clinically masked by hepatolithiasis and biliary obstruction, creating a significant diagnostic pitfall in routine practice. Case presentation A 63-year-old woman presented with recurrent upper abdominal pain for more than 1 year, which had worsened over the preceding 10 days. Routine laboratory tests were unremarkable except for a mildly elevated carbohydrate antigen 19-9 level of 39.8 U/mL. Contrast-enhanced CT demonstrated a focal intraductal lesion in the left intrahepatic biliary system with adjacent cystic or aneurysmal dilatation of the affected bile duct, producing the appearance of localized high biliary obstruction. MRI and MRCP further confirmed marked unilateral dilatation of the left intrahepatic bile ducts with focal obstructive change and associated intraductal abnormality. After comprehensive preoperative evaluation, the patient underwent open left hepatectomy. Intraoperatively, a markedly dilated bile duct containing intraductal papillary adenomatous tissue and gelatinous material was identified. Histopathological examination confirmed intrahepatic IPNB with low-grade dysplasia, pancreatobiliary type. No invasive carcinoma was identified, and all resection margins were negative. Immunohistochemistry showed positive staining for CK19, CK7, MUC1, MUC5AC, and MUC6, with negative staining for MUC2. The postoperative course was uneventful, and the patient was discharged on postoperative day 10. No recurrence or major complication was observed during 2 years of follow-up. Conclusion In patients with hepatolithiasis and recurrent biliary symptoms, unilateral or focal intrahepatic duct dilatation and localized obstructive biliary abnormalities should prompt consideration of IPNB rather than uncomplicated stone disease alone. Early recognition, definitive surgical resection for localized disease, and complete pathological evaluation are essential for accurate diagnosis, risk stratification, and follow-up planning.