Autoimmune forms of chronic hepatitis associated with hepatitis C virus (HCV) infection with and without HCV-RNA: histological differences from pure autoimmune hepatitis and chronic hepatitis C.

Liver biopsy specimens of pure autoimmune hepatitis (pAIH), autoimmune forms of chronic hepatitis with positivity for anti-hepatitis C virus (anti-HCV) and negativity for HCV-RNA (cAIH-RNA(-)), autoimmune forms of chronic hepatitis with positivity for anti-HCV and HCV-RNA (cAIH-RNA(+)), and chronic hepatitis C (CHC) were compared histologically and statistically to clarify the histological character of the autoimmune form of chronic hepatitis with HCV infection. The following representative histological features were used to investigate: inflammation, fibrosis, plasma cell infiltration, lymphoid aggregates/follicles, non-suppurative destructive cholangitis, and the shape of the enlarged portal tracts. While a considerable overlap in histological features between the pAIH and cAIH-RNA(-) groups and between the CHC and cAIH-RNA(+) groups was recognized, the overlap between the pAIH and CHC groups was small. Significant differences were found between cAIH-RNA(-) and cAIH-RAN(+) groups, especially in necroinflammatory findings. In conclusion, most cases of cAIH-RNA(-) with histological features similar to those of pAIH were shown to be AIH. The remaining cases might be CHC with subsidence of viral duplication. Conversely, many cases of cAIH-RNA(+) with histological findings similar to those of CHC were shown to be CHC clinically mimicking pAIH. The remaining cases might represent coexistence of pAIH and HCV infection.