Abstract
BACKGROUND: The simultaneous positivity of hepatitis B surface antigen (HBsAg) and its corresponding antibody (anti-HBs) is a rare serological paradox in chronic hepatitis B. Its pathogenesis is not fully understood but may involve hepatitis B virus (HBV) S gene mutations leading to immune escape or complex host immune dysfunction. Recognizing this pattern is clinically important, as it may indicate advanced liver disease. CASE REPORT: A 54-year-old man with no history of alcohol abuse or liver disease presented with persistent bloating and dyspepsia. Laboratory tests revealed concurrent positivity for HBsAg (1438.5 S/Co) and anti-HBs (136.6 mIU/ml), hepatitis B e antigen (HbeAg) positivity, and a high HBV deoxyribonucleic acid (DNA) viral load (4.3 ×10(6) copies/ml). Transaminases were mildly elevated, platelet count was reduced, and liver elastography indicated cirrhosis (F4). The patient was diagnosed active chronic hepatitis B with concurrent HBsAg and anti-HBs positivity, complicated by compensated cirrhosis and started on tenofovir 300 mg daily. After 4 months of treatment, the patient showed clinical improvement, with marked reductions in liver enzyme levels and HBV DNA viral load. CONCLUSION: The concurrent positivity of HBsAg and anti-HBs is a rare serological finding that may reflect a complex HBV infection with a higher risk of progressive liver disease. This case illustrates that this unusual serological pattern can be associated with a high viral load and cirrhosis, highlighting the need for close monitoring of liver function, HBV DNA levels, and antiviral treatment response. LEARNING POINTS: Rare serological finding involving concurrent HBsAg and anti-HBs positivity in chronic hepatitis B with cirrhosis.Pattern that may indicate immune escape and active viral replication requiring closer clinical attention.Close monitoring of liver function, hepatitis B virus deoxyribonucleic acid levels, and antiviral treatment response is essential in such cases.