Is statin-induced myositis part of the polymyositis disease spectrum?

Statin medications have recently been shown to cause not only a toxic myopathy but also an immune-mediated necrotizing myositis. Before the discovery of a specific anti-HMG-CoA reductase antibody occurring in conjunction with a necrotizing myopathy, many of these patients may have been classified as polymyositis. They present similarly with proximal muscle weakness, elevated muscle enzymes, persistence of symptoms despite cessation of the statin, with need for immunosuppression. This article provides an overview of this novel disease entity by placing it in the context of existing idiopathic inflammatory myopathy (IIM) classification criteria, and in the range of statin-associated muscle toxicity.