Fatal Hepatitis B Virus Reactivation Following Immunosuppressive Therapy in a Patient with an Atypical Hepatitis B Virus Serological Profile: A Case Report

Hepatitis B virus (HBV) reactivation is a well-recognized complication in patients with lymphoma receiving immunosuppressive therapy, particularly rituximab-containing regimens. We describe a 58-year-old man with diffuse large B-cell lymphoma and an atypical baseline HBV serological profile: hepatitis B surface antibody (anti-HBs) positivity (102.00 U/L), antibody to hepatitis B core antigen negativity, a low-level hepatitis B surface antigen (HBsAg) result (0.35 COI, reported as negative by the local laboratory), and undetectable HBV DNA. Thirteen days after initiation of the fourth cycle of modified R-CHOP (rituximab, cyclophosphamide, pirarubicin, vinorelbine and dexamethasone) chemoimmunotherapy, the anti-HBs titer had decreased to 1.31 S/CO, the HBsAg level to 0.02 S/CO, and HBV DNA was not reassessed until reactivation. Approximately 16 weeks after treatment completion, the patient developed fatigue, anorexia, and jaundice. HBsAg increased from 28.66 S/CO to 8048.30 IU/mL, hepatitis B e antigen became positive, and HBV DNA increased to 1.94 × 109 IU/mL. Despite treatment with tenofovir alafenamide fumarate and plasma exchange, the patient died of refractory liver failure and hepatic encephalopathy. These findings suggest that atypical serological profiles may not reliably indicate a low risk of severe HBV reactivation during intensive immunosuppressive therapy. Comprehensive pretreatment risk assessment and long-term monitoring of anti-HBs titers, HBsAg, and HBV DNA during and after therapy may facilitate earlier detection and intervention.