Intraductal papillary neoplasm of the bile duct with metachronous development in the downstream bile duct after radical resection

We report a case of intraductal papillary neoplasms of the bile duct (IPNB) that metachronously developed twice in the downstream bile duct after radical resection. The first lesion was located in the left intrahepatic bile duct, the second lesion in the perihilar bile duct, and the third lesion in the distal bile duct. All lesions were IPNBs with associated invasive carcinoma (pancreatobiliary type). The depth of invasion was to the Glisson’s capsule in the first lesion, to the subserosa in the second lesion, and to the fibromuscular layer in the third lesion, without lympho-vascular/perineural invasion and lymph-node metastasis. These were resected radically and had no biliary intraepithelial neoplasia and hyperplasia in the surrounding mucosa. In immunohistochemical examination, each lesion showed a different pattern. Although the downstream occurrence suggests intrabiliary dissemination, the mechanism of these metachronous developments may be multicentric. A literature review revealed that most metachronous cholangiocarcinomas have a grossly papillary appearance and tend to arise downstream. Our findings suggest that IPNB may develop metachronously in the residual bile duct after radical surgery, which may assist in early detection.