Abstract
A 69-year-old man was referred to our department with acute hepatitis. He had been newly treated with benidipine hydrochloride for two months. His blood test results were as follows: aspartate aminotransferase, 1,614 IU/L; alanine aminotransferase, 1,091 IU/L and anti-smooth muscle antibody, ×80. Needle liver biopsy specimen showed interface hepatitis with mainly lymphocytic infiltration and bridging fibrosis in the periportal area. Immunohistochemistry revealed lymphocytic infiltration positive for IgG4. We diagnosed him with IgG4-related AIH with an etiology that was suspected of being drug-induced. Oral prednisolone was started and then tapered after achieving biochemical remission. Hepatitis recurred after the cessation of steroids; however, remission was achieved with ursodeoxycholic acid.