Polymyositis occurring during alpha-interferon treatment for malignant melanoma: a case report and review of the literature.

Polymyositis is a systemic autoimmune disorder characterised by proximal muscle weakness which most frequently involves the limbs, neck and trunk. Alpha interferon is an antiviral molecule with well-known immunomodulatory and antiproliferative effects, but its use is often associated with a variety of side effects, in particular autoimmune phenomena. We report the occurrence of polymyositis during treatment with alpha-interferon in a patient affected by malignant melanoma. Indirect evidence suggests that in this case the patient's myositis was not linked to her neoplasia, since the melanoma was confirmed to be in remission both at the time of the diagnosis of the muscle disease and again after more than one year of follow-up.