Intraductal Papillary Neoplasm of the Bile Duct Arising From a Background of Autoimmune Hepatitis: A Case Report

Abstract

Intraductal papillary neoplasm of the bile duct (IPNB) is a rare cystic tumor of the liver defined separately from hepatic mucinous cystic neoplasm. Development of liver cancer in patients with autoimmune hepatitis (AIH) is also sporadic, and such cases reported previously have been hepatocellular carcinoma. Here we report a 50-year-old man with IPNB complicated by AIH who underwent a successful extended left hepatectomy. Histopathology and immunohistochemical staining of the resected tumor revealed that it was a pancreatobiliary-type IPNB expressing both MUC5AC and MUC6, accompanied by carcinoma in situ expressing p53, Ki-67 and CA19-9. The histopathology of the background liver was compatible with that of AIH showing interface hepatitis with accompanying plasma cell infiltration. The patient has remained free of cancer recurrence for 12 years following the hepatectomy, and liver dysfunction caused by AIH has been controllable by steroid administration. This is the first report of pancreatobiliary-type IPNB associated with AIH.