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

Abstract

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.