Delayed Hepatitis B Virus Reactivation at 33 Months after the Completion of Rituximab-based Chemotherapy.

We herein report a case of hepatitis B virus (HBV) reactivation in a female patient in her 70s with isolated anti-hepatitis B core (IAHBc) antibodies [HB surface antigen (HBsAg)-negative, HB surface antibody (HBsAb)-negative, and HB core antibody (HBcAb)-positive], receiving rituximab-based chemotherapy for follicular lymphoma. Her serum HBV DNA was negative. The patient was treated with rituximab for 21 months, and 33 months after completion of treatment, her HBV DNA level increased to 5.1 Log IU/mL, and the patient developed hepatic failure. Tenofovir alafenamide fumarate treatment was initiated for HBV reactivation, and DNA was not detected 9 months later.