[Extrahepatic manifestations of hepatitis C virus infection]

HCV virus is associated with various immunological disorders. Some of them like mixed cryoglobulinemia, are proved by molecular biology and virology. Others are presumed auto-immune: auto-antibodies production (antinuclear, anti-smooth muscle, anti-liver-kidney microsomal antibodies...) has generally no pathological significance; however, true auto-immune diseases such as auto-immune hepatitis type 1 or 2, Sjögren's syndrome, lichen planus and auto-immune thyroiditis can be associated with HCV related liver disease. Finally, the association of some extra-hepatic manifestations like porphyria cutanea tarda with hepatitis C virus are only based on epidemiological data. Alpha interferon, the reference treatment of chronic hepatitis C, can be efficient on manifestations such as cryoglobulinemia which are directly linked to the virus. However, because of its immunological effect, the same treatment can severely worsen auto-immunological diseases associated with hepatitis C virus (autoimmune hepatitis, thyroiditis...). In practice, it's of great importance to identify and classify these extra-hepatic manifestations to optimize the treatment of chronic hepatitis C.