Case Report: Multimodal treatment for two unresectable intraductal papillary mucinous neoplasms of the bile duct and literature review.

Intraductal papillary mucinous neoplasm of the bile duct (IPMN-B) is a rare biliary tumor with marked heterogeneity. We report two cases of unresectable IPMN-B, both treated with gemcitabine plus oxaliplatin (Gemox)-based hepatic arterial infusion chemotherapy (HAIC) combined with tislelizumab and surufatinib. According to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), calculated using the longest diameter of the target lesion, case 1 achieved radiographic stable disease (SD) and improvement in laboratory indices after two cycles of HAIC combined with targeted immunotherapy, followed by one cycle of maintenance therapy with tislelizumab plus surufatinib. Case 2 achieved radiographic partial response (PR) after four cycles of treatment, accompanied by marked improvement in abdominal pain and cholestatic indices. No severe treatment-related adverse events occurred in either patient, and both remained alive at the last follow-up. To place these observations in the context of existing evidence, we further reviewed the epidemiology, clinical manifestations, pathological and imaging features, treatment strategies, and prognosis of IPMN-B based on the available literature. These two cases suggest that multimodal combination therapy may have potential value in unresectable IPMN-B, although the durability of response, long-term safety, and the subgroups most likely to benefit still require further study.