Abstract
An 81-year-old man underwent rituximab-containing chemotherapy for chronic lymphocytic leukemia (CLL). Thirteen years after his last chemotherapy, he was diagnosed with hepatitis B virus (HBV) reactivation. He was then treated with entecavir, and improvement was seen in his liver injury. He developed diffuse large B cell lymphoma (DLBCL) after improvement in his hepatitis. Despite chemotherapy, he contracted the coronavirus disease 2019 (COVID-19) and died of COVID-19. We suspect that HBV reactivation was triggered by DLBCL. When HBV reactivation occurs a long time after chemotherapy has concluded, the onset of DLBCL should be considered.