We herein report a child case of autoimmune hepatitis (AIH) accompanied with Graves' disease. Elevated aminotransferase levels were found in a 12-year-old Japanese girl with Graves' disease. In her first liver biopsy, necrosis and inflammation was limited to the centrilobular area, while the second biopsy showed different findings. Namely, portal injury newly appeared, including interface hepatitis, which represents the histological characteristics of AIH. As the histological findings at the onset of AIH do not always show typical findings, a re-biopsy is considered to be important in individuals suspected to have AIH. AIH should be included in the differential diagnosis of liver dysfunction in Graves' disease, even in children.
Keywords: Graves' disease; autoimmune hepatitis; interface hepatitis; liver histology; pediatric case.