[Interferon-alpha-associated polyarthritis. Possible induction of seropositive rheumatoid arthritis by interferon-alpha: two case reports and review of the literature].

We describe a patient with chronic myelogenous leukemia (CML) and a patient with hairy cell leukemia being effectively treated with alpha-interferon who developed a seropositive chronic polyarthritis formally fulfilling the ACR criteria for rheumatoid arthritis. Because of its efficacy, interferon was not discontinued, and the arthritis treated with low-dose prednisolone or NSAIDS. These are the 19th and 20th case of symmetrical polyarthritis during alpha-interferon therapy fulfilling the criteria for RA. The possible mechanisms of the relatively frequent appearance of autoimmune diseases during interferon therapy are discussed.