Statin-Induced Necrotizing Autoimmune Myositis Presenting With Progressive Limb-Girdle Weakness Following Low-Dose Atorvastatin Use

Statins are a mainstay in the prevention of cardiovascular disease and are associated with rare adverse effects, including statin-induced necrotizing autoimmune myositis (SINAM). This condition is characterized by progressive, symmetric, proximal muscle weakness and elevated creatine kinase (CK), persisting despite discontinuation of the statin, and is confirmed by the presence of anti-HMG-CoA reductase (HMGCR) antibodies. We present a case of a 72-year-old male who presented with three months of progressive limb-girdle weakness with chronic use of low-dose atorvastatin (10 mg). Our review of the literature suggests that this is the first documented case of SINAM in the setting of low-dose atorvastatin usage. Diagnosis was confirmed by anti-HMGCR antibodies. The patient was initially managed with corticosteroids and methotrexate but required escalation to intravenous immunoglobulin (IVIG), which led to functional improvement. This case underscores the need for high clinical suspicion for SINAM and highlights the importance of consideration for early aggressive immunosuppression.