CONCLUSIONS

The exact incidence of extrahepatic disease manifestations in chronic HCV infection is uncertain but may range up to 40%.⁴ The prevalence of peripheral neuropathy in HCV infection has been reported at approximately 15% but may be substantially higher on detailed electrophysiologic testing.² Polyneuropathy is usually distal and sensory, but can also present as a multiple mononeuropathy. Epineural vasculitic infiltration and endoneural microangiopathy may be seen on nerve biopsy and a striking mononuclear cell infiltrate on muscle biopsy. An important consequence of chronic HCV is the accumulation of circulating immunocomplexes and autoimmune phenomena. Mixed cryoglobulinemia, the most common extrahepatic manifestation of HCV, is a systemic vasculitis characterized by the deposition of circulating immunocomplexes in small and medium-sized blood vessels and can be found in up to 60% of patients, although the syndrome of cryoglobulinemic vasculitis occurs in only 5% to 10%.^4,5 A few cases of polyarteritis nodosa–like disease affecting the medium-sized vessels have been reported.⁶ Our patient was thought to have mononeuritis multiplex and the sural nerve biopsy revealed CD20 and CD79a positive B-cell infiltrates. Associations between chronic HCV and non-Hodgkin lymphoma have been made. HCV is a lymphotrophic virus, which may proliferate in B cells. B-cell clonal expansion underlies mixed cryoglobulinemia and is responsible for the increased presence of autoantibodies. In association with a Bcl2/JH rearrangement, type II mixed cryoglobulinemia can evolve into a frank B-cell non-Hodgkin’s lymphoma in approximately 8% to 10%.³ In addition to cryoglobulinemia and vasculitis, B-cell lymphoma should also be considered in the differential diagnosis of HCV polyneuropathy.