Lichen planus and hepatitis C virus infection: an updated critical review.

An association between lichen planus (LP) and liver diseases has been reported. PubMed database has been used to extract information on hepatitis C virus (HCV) infection and LP. The results suggest that LP, mainly the oral type, is significantly associated with HCV infection in Southern Europe and Japan but not in Northern Europe. These differences may be related to genetic factors. Detection of HCV viral sequences and HCV-specific CD4+ and/or CD8+ T lymphocytes in oral samples of LP patients suggests that HCV might be involved in the development of oral lesions via an immunological pathway, characterized by an excessive production of Th1 cytokines following an uneffective antiviral immuno-response.