Statin-induced necrotising autoimmune myopathy: a rare complication of statin therapy

Statin-induced necrotising autoimmune myopathy (SINAM), a rare complication of statin use, presents with significant proximal muscle weakness and raised creatine kinase (CK) levels (50-100 times). This is different from other musculoskeletal conditions caused by statin use. Anti-hydroxy-methyl-glutaryl-coenzyme A reductase (HMG-CoA) reductase antibody is usually positive in SINAM and it generally indicates good response to immunosuppressive medications. We report a case of a 52-year-old man who presented with a 2-month history of significant upper and lower extremity proximal muscle weakness and a CK level of >10 000. He was started on atorvastatin for myocardial infarction 3 years ago. MRI pelvis, including proximal thigh, showed diffuse muscle oedema to all muscle groups. Muscle biopsy was suggestive of necrotising myopathy. His HMG-CoA reductase antibody was also positive. His treatment regimen consisted of immunosuppressants, including steroids. He also required extensive physiotherapy and showed response to treatment when reviewed in the outpatient clinic 9 months later.