Hepatitis C virus infection-associated non-cryoglobulinaemic monoclonal IgMκ gammopathy responsive to interferon-α treatment

Background/Aims: An association of HCV infection with lymphoproliferative disorders, particularly B-cell non-Hodgkinʹs lymphoma has been described. In the majority of reported patients, mixed cryoglobulinaemia was present as well. Rarely, HCV-associated lymphoproliferative disorders have been observed in the absence of cryoglobulinaemia. In these latter patients, the response to interferon-α is largely unknown. Case Report: We report a case of an asymptomatic 31-year-old male with chronic HCV infection and non-cryoglobulinaemic monoclonal IgMκ gammopathy responsive to interferon-α therapy. Prior to therapy, elevated plasma transaminase activities known for longer than a year, serum anti-HCV antibodies and HCV RNA detected by reverse transcriptase-polymerase chain reaction were presnet. Serum IgM concentration was markedly elevated, immunofixation demonstrated monoclonal serum IgM, and urine κ-light chains were detected. Cryoglobulins were undetectable in several consecutive serum samples. Bone marrow aspirate and biopsy specimens were unremarkable. Further evaluation, e.g. by ultrasonography and radiography, did not reveal evidence for lymphoma. Treatment with interferon-α2a for 12 months resulted in a long-term sustained response to HCV infection and in a normalisation of serum IgM concentration. Conclusion: Therefore, the corresponding effects of interferon-α on HCV infection and on a monoclonal B-cell population observed in the present case might suggest a pathogenetic connection, similarly, to what has been described for HCV and mixed cryoglobulinaemia. The molecular events, however, leading to HCV-induced monoclonal B-cell expansion remain unknown.