Pathological characterization of occult hepatitis B virus infection in hepatitis C virus-associated or non-alcoholic steatohepatitis-related hepatocellular carcinoma

Occult hepatitis B virus（HBV） infection, by definition, is a state in which infection with this virus does not manifest with the conventional diagnostic laboratory criteria reserved for the obvious form of HBV infection. As a result,occult HBV infection is commonly a surprise finding discovered accidently during the evaluation of other apparent liver diseases, such as hepatitis C virus（HCV） infection or non-alcoholic fatty liver disease and, more importantly, their evolution into life-threatening hepatocellular carcinoma. As infection with HCV and occult HBV is rarely considered when assessing these more obvious conditions, and in an attempt to offer a better understanding of this phenomenon,this study attempted to shed some light onto the uniqueness of occult HBV infection by addressing the natural history of HBV and HCV infections, as well as non-alcoholic fatty liver disease. This was carried out by taking into account the exclusive integration process undertaken by the HBV genome into infected host hepatocytes, with consideration given to conditions which afford reactivation of the occult infection and stress on the molecular mechanisms that underlie occult HBV infection. Finally, the clinical outcome of occult HBV infection and its relation to hepatocellular carcinoma is analyzed.