Hepatitis C virus infection, type III cryoglobulinemia, and necrotizing vasculitis.

A 53-year-old man with chronic hepatitis-C virus infection presented with livedo reticularis, purpura, and leg ulcers. A skin biopsy specimen showed a necrotizing vasculitis. The skin biopsy specimen and serology confirmed the diagnosis of type-III cryoglobulinemia. Bone marrow and peripheral blood showed proliferation of atypical CD5-positive B cells that included a monoclonal population. There is growing evidence that chronic hepatitis-C infection can result in immune dysregulation and expansion of autoimmune B cells that produce cryoglobulins.