Strategy for Discriminating Intraductal Papillary Neoplasm of the Bile Duct (IPNB) in Different Anatomical Locations Based on Clinicopathological Features and Outcomes

Abstract

Introduction: In the statement by the Japan-Korea expert pathologists, it was described that Intraductal papillary neoplasm of bile duct (IPNB) can be subclassified into two types. Each of these two types has a different tendency in the anatomical location and invasiveness. The present study assessed the clinical features and outcomes of intra-/extra- hepatic IPNB to establish optimal therapeutic strategies for IPNB. Method: The present study included 28 cases who were pathologically diagnosed with IPNB. These cases were classified by the anatomical location where it arises (intrahepatic-IPNB 7 cases/ extrahepatic-IPNB 21 cases). Furthermore, we attempted to further clarify the characteristics of intrahepatic IPNB by comparing with intrahepatic cholangiocarcinoma (ICC). Results: Superficial extension was significantly more frequent in extrahepatic type with 17 cases (p=0.003). Pathologically, lymphatic invasion was significantly more frequent in the extrahepatic type (p=0.033), and mucus production tended to be more frequent in intrahepatic type (p=0.063). In terms of prognosis, recurrence was observed in 9 cases of extrahepatic type. As compared with 26 cases of ICC, preoperative intrahepatic (p=0.026) and extrahepatic (p<0.01) biliary dilatation and histological mucus production (p<0.01) were significantly found in primary hepatic IPNB. ICC group significantly showed CA19-9 >100 (p=0.043), portal invasion (p<0.01) and recurrence (p<0.01). Conclusions: Preoperative diagnosis of intrahepatic IPNB is possible because of the relatively common and characteristic imaging findings. However, considering the malignant potential in patients with high tumor markers and portal vein invasion, as well as the characteristics of horizontal extension of IPNB, systematic hepatectomy with adequate bile duct resection are recommended.