Hepatitis C: reviewing the options
==================================

* Sujoy Khan
* W.A.C. Sewell

Tom Wong and Samuel Lee1 mention some extrahepatic manifestations of infection with hepatitis C virus (HCV), but they do not discuss the urticarias. Internists and primary care physicians need to be aware that several forms of urticaria can be associated with asymptomatic HCV infection.

The link between HCV and urticaria is controversial,2 because various studies have failed to differentiate between acute urticaria, chronic urticaria and urticarial vasculitis, all of which have been proposed as being associated with HCV infection. The estimated prevalence of urticaria varies from 1.8% to 24%, and one case–control study disputed the association altogether.2 The association with other hepatitis viruses is more certain. For example, electron microscopy was used to identify hepatitis B surface antigen-antibody complexes in cryoprecipitates taken from patients during the acute urticarial episode.3

Immune-complex deposits of viral hepatitis can activate the complement system, which results in a serum-sickness-like syndrome, with arthritis, excruciating headache and urticaria (known as Caroli's triad).4 Urticaria resolves on treatment with interferon, and more benefit is seen when urticarial vasculitis is associated with mixed essential cryoglobulinemia.5

HCV testing should not be a routine screening test for all urticarias, but it is good clinical practice to consider viral marker studies in a patient with urticaria who presents with icterus or elevated transaminase levels (or both). The awareness that urticaria or urticarial vasculitis may be caused by hepatitis C is important, as early antiviral treatment can reduce significant morbidity and mortality.

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