Introduction : Intraductal papillary neoplasm of the bile duct (IPNB) is a recently defined concept and its clinicopathologic characteristics and diagnostic criteria have not been well established yet. We performed this study to clarify the clinicopathologic features of IPNB and to find out the optimal morphologic criteria.

Methods : Between 1997 and 2016, 589 patients who previously diagnosed as IPNB in 23 tertiary referral centers of Korea were collected and finally 457 patients were included in this study. Every case was reviewed by 3 or 4 biliary-pancreas pathologists.

Results : Patient’s mean age was 65.5 years. The 5-year overall survival rate of all the patients was 80.6% and 104 (24.6%) patients underwent recurrence during the follow-up periods. Patients with the intestinal type (n=237; 52.2%) was the majority in the histologic subtypes of IPNB. One hundred and eight patients (23.6%) were diagnosed as IPNB with associated carcinoma. Among 457 patients, 451 (98.7%) had bile duct dilatation and 430 (94.1%) had intraductal mass on preoperative computed tomography (CT). We applied ‘Japan Biliary Association (JBA) classification’ and ‘modified anatomical classification’ to compare the morphological features.

Conclusions : IPNB, which is thought to be a precursor lesion of cholangiocarcinoma, show better long-term survival and prognosis after optimal surgical resection. As one of the prevalent nations of cholangiocarcinoma, this is the first multi-center collaboration study of IPNB in Korea. In the future, we are planning the Korea-Japan collaboration study to establish the disease criteria and find out the clinicopathologic and radiologic characteristics of IPNB in the future.