Viral hepatitis leads to liver cell apoptosis. A mononuclear inflammatory cell infiltrate extends from portal areas and disrupts the limiting plate of hepatocytes which are undergoing apoptosis, the so-called interface hepatitis of chronic active hepatitis. In this case, the hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (HBcAb) were positive, but anti-HBs (seen with recovery) was negative.

The severity of infection relates to the immune system's ability to clear the virus. If clearance is delayed, a chronic persistent hepatitis can occur. A poor response can lead to chronic active hepatitis with ongoing hepatocellular damages and liver remodeling, with consequences of cirrhosis and potentially hepatocellular carcinoma.

Hepatitis B viral DNA can be measured by PCR. HBV DNA >2000 copies/mL along with an elevated alanine aminotransferase (ALT) suggests further workup and possible therapy is needed. Viral copies/mL above 10,000 suggest ongoing hepatitis with greater risk for carcinoma.