[Hepatitis C infection with false negative serology in a patient with mixed cryoglobulinemic vasculitis].

HISTORY AND ADMISSION FINDINGS

A 72-year-old man with nausea, fever and elevated inflammatory parameters was transferred for further diagnostic assessment and treatment. On examination a palpable purpura was obvious without any signs of infection.

INVESTIGATIONS

Creatininekinase was 350 mmol/l with a proteinuria of 20 g per day. Histological examination revealed hypersensitivity vasculitis in the cutis and a membranoproliferative glomerulonephritis. In addition there was a mixed cryoglobulinemia with a negative test for hepatitis C virus. Further investigation revealed hepatitis C virus RNA genotype 1 b in the cryoprecipitate.

DIAGNOSIS AND TREATMENT

The patient was successfully treated with with interferon alpha for 12 month. The nephrotic syndrome improved and the proteinuria ceased

CONCLUSION

Mixed cryoglobulinemias are associated with hepatitis C virus infection in over 80% of cases. Normally it is easy to make the diagnosis serologically with an ELISA test. But in a few cases the virus RNA is only detectable in the cryoprecipitate. If there is a high suspicion of an hepatitis C infection with cryoglobulinemia but HCV serology is negative, it is essential that virus antigen and antibodies are searched for in the cryoprecipitate.