A 66-year-old man presented with subacute, progressive bilateral proximal extremity pain and weakness. He had been on atorvastatin 10 mg for four years. Physical exam was significant for reduced muscle strength involving his proximal muscles in the upper and lower extremities.

Initial labs were significant for an elevated creatinine kinase (CK) of 3503 U/L and markedly elevated HMG-CoA reductase Antibody (>200 units). An electromyogram and nerve conduction study demonstrated a diffuse and active irritable myopathy. Treatment with monthly IVIG 1g/kg and high dose steroids was initiated, and shortly after he developed renal injury. Muscle biopsy of the left biceps brachii revealed a necrotizing myopathy with perivascular inflammation and necrosis of medium sized vessels. P-ANCA antibody was positive and kidney biopsy showed necrosis and fibrocellular crescent formation in numerous glomeruli.

With ongoing immunosuppression, the patient has had complete remission of his vasculitis and myositis.