Abstract
Hepatitis C virus (HCV) infection can cause various manifestations, including rare biliary complications. This case details a 44-year-old Thai woman with severe biliary pain but normal blood counts, liver function, and amylase levels. Abdominal MRI, MRCP, and endoscopic ultrasound ruled out mechanical obstruction but revealed diffuse thickening of the intrahepatic and common hepatic bile duct walls, and soft tissue thickening surrounding the left portal vein branch, suggestive of an inflammatory process. Further investigation confirmed positive HCV RNA. Serology revealed low complement levels, suggesting immune-mediated inflammation, though ANA, ANCA, and cryoglobulin were negative. Serum IgG4 levels were also normal. This led to a diagnosis of small vessel vasculitis of the biliary tract secondary to chronic HCV infection. Treatment with antiviral therapy and a short course of prednisolone resulted in significant symptom improvement. This case underscores the need for increased awareness of biliary complications associated with chronic HCV infection.