Hepatitis D virus (HDV) is a defective RNA virus requiring hepatitis B virus (HBV) for replication, and co-infection of them significantly accelerates liver inflammation, fibrosis, and hepatocarcinogenesis. Recent studies have reported that the prevalence of HDV infection is extremely high in certain regions, such as Mongolia, exceeding 50% among individuals infected with HBV. To clarify the potential presence of HDV infection in Japan, we retrospectively examined 95 surgically resected cases for HBV-related hepatocellular carcinoma (HCC) at Tokushima University Hospital between 2003 and 2023. Formalin-fixed, paraffin-embedded liver tissues were subjected to immunohistochemistry using an antibody against large and small delta antigens of HDV. Plasma samples from 12 patients were additionally tested by ELISA. As a result, none of the HBV-related HCC cases showed immunoreactivity for HDV antigens in either tumor or non-neoplastic tissues, and all available plasma samples were negative by ELISA. These findings suggest that HDV infection is either absent or extremely rare among patients with HBV-related HCC in this cohort. Our results align with prior seroprevalence estimates and provide histopathological evidence supporting minimal contribution of HDV to liver carcinogenesis in Japan, contrasting sharply with patterns in hyperendemic regions. J. Med. Invest. 73 : 52-54, February, 2026.
Ogawa et al. (Thu,) studied this question.