A Case of Acute Necrotizing Myopathy in a Patient with Systemic Lupus Erythematosus

BACKGROUND Systemic lupus erythematosus (SLE) is an autoimmune disorder affecting multiple organ systems with a wide spectrum of clinical presentation and associated with positive serologies. Musculoskeletal involvement in patients with SLE is relatively uncommon, occurring in approximately 4% to 16% of cases. Some patients can develop necrotizing myopathy without myositis. MRI in patients with SLE-associated necrotizing myopathy usually shows interstitial edema, while muscle biopsy often shows type 2 muscle fiber atrophy. We herein report an unusual case of acute necrotizing myopathy in a patient recently diagnosed with SLE. This case report focuses on the pertinent features related to the diagnosis of this patient while highlighting the management of acute necrotizing myopathy. CASE REPORT A 30-year-old African American woman presented to the Emergency Department with skin rashes, myalgia, polyarthralgia, and muscle weakness resulting in the inability to walk, 2 weeks after being diagnosed with SLE. Laboratory analysis showed elevated creatine kinase and myoglobin. She was found to have both MRI and biopsy findings suggestive of necrotizing myopathy. She was treated with mycophenolate mofetil and steroids, with an improvement of muscle strength and decrease in creatine kinase over a 2-week period. CONCLUSIONS Immune-mediated necrotizing myopathies are a rare group of debilitating myopathies that can be associated with SLE. The diagnosis of necrotizing myopathy in patients with SLE requires a high index of suspicion and careful work-up to establish a diagnosis. Muscle biopsy often shows type 2 muscle fiber atrophy. Immunosuppressive therapy is the mainstay of treatment, and early initiation of immunotherapies is associated with an improvement in patient outcomes.