Myositides comprise a large group of disorders involving limb muscle weakness. In differential diagnosis we have to consider idiopathic myositides, myositides associated with other diseases, and those induced by external factors, e.g. drug-induced. Statins are commonly used drugs, but many patients experience a broad spectrum of adverse effects including symptoms from skeletal muscle. Physicians should pay special attention to patients reporting muscle weakness lasting longer than 12 weeks, despite statin withdrawal, as well as other symptoms: dysphagia, disturbed grip function, elevated creatinine kinase (CK) levels and abnormal electromyography.
The reported case deals with the problem of differential diagnosis of drug-induced muscle injury, polymyositis with a recently reported myopathy – statin-induced autoimmune necrotizing myositis, related to anti-HMGCR antibodies.