A case of clonorchiasis with focal intrahepatic duct dilatation mimicking an intrahepatic cholangiocarcinoma.

Biliary strictures can be caused by various diseases. Intrahepatic duct (IHD) strictures are usually related to IHD stones and cholangitis. However, focal IHD strictures without IHD stones often create diagnostic problems. Parasitic diseases such as clonorchiasis can be a rare cause of an IHD stricture. Human clonorchiasis (Clonorchis sinensis infection) is an endemic parasitic disease in Eastern Asia, including Korea, and patients acquire the infestation by eating raw fish. On radiological examinations, clonorchiasis shows typically diffuse, minimal, or mild dilatation of the small IHD, particularly in the periphery, without dilatation of the extrahepatic duct. However, diagnosis of clonorchiasis can sometimes be difficult when radiological changes are atypical. We report a case of focal left IHD dilatation caused by clonorchiasis that was confused with a malignancy.