Fatal Acute Liver Failure Associated With Presumed Hepatitis B Virus Reactivation During Rituximab Maintenance Therapy: A Case Report.

We report a woman in her 60s with follicular non-Hodgkin lymphoma receiving maintenance rituximab therapy, last administered one month prior to presentation, who developed progressive malaise, jaundice, and acute liver failure. Laboratory evaluation demonstrated severe hepatocellular injury with marked transaminase elevations (alanine aminotransferase: 2,500 U/L; aspartate aminotransferase: 2,400 U/L), hyperbilirubinemia (total bilirubin: 20 mg/dL), and coagulopathy. Hepatitis B virus (HBV) serology demonstrated active infection with elevated hepatitis B surface antigen (HBsAg) and detectable HBV DNA. Baseline HBV screening and antiviral prophylaxis records prior to rituximab initiation were unavailable from the treating institution, limiting the definitive confirmation of pre-existing HBV status. Given the patient's recent rituximab exposure, clinical presentation, and exclusion of alternative etiologies, HBV reactivation was considered the most likely diagnosis. The patient was diagnosed with HBV reactivation associated with rituximab therapy. Despite the initiation of antiviral treatment and aggressive supportive care, her clinical course rapidly deteriorated, complicated by hepatic encephalopathy, acute kidney injury requiring hemodialysis, and hypoxic respiratory failure. She was evaluated for liver transplantation but deemed ineligible due to multiorgan failure and ultimately transitioned to end-of-life care. This case highlights the potentially fatal consequences of HBV reactivation during rituximab therapy and underscores the importance of appropriate screening, prophylaxis, and vigilance in high-risk patients.