[Active arthritis due to cryoglobulinemia based on HCV infection in a patient with RA improvement of arthritis with IFN-alpha].

: A 49-year-old Japanese woman was diagnosed with rheumatoid arthritis (RA) based on ACR criteria in May 1999. She developed liver injury after initiation of disease-modifying antirheumatic drugs (DMARDs) and was found to have contracted HCV infection. RA disease activity worsened following restriction of medication due to liver dysfunction. However, 3 mg/day of prednisolone (PSL) resulted in a temporary but marked improvement of RA in December 2001; but arthritis recurred along with Raynaud's phenomenon and palpable purpura. Differential diagnosis between arthritis caused by cryoglobulinemia and exacerbation of RA was important for the selection of appropriate treatment. She manifested non-erosive arthritis on medium and large joints with proteinuria, hematuria and hypocomplementemia. In addition, type III cryoglobulin was detected and chronic active hepatitis was observed on liver biopsy in March 2002. We considered that the main cause for the arthritis was HCV-related mixed cryoglobulinemia. Administration of IFN-alpha resulted in the disappearance of HCV-RNA and cryoglobulin followed by amelioration of arthritis without exacerbation of RA.