Immune-mediated Necrotizing Myopathy

Immune-mediated necrotizing myopathy is an autoimmune myopathy characterized by proximal muscle weakness and elevated creatine kinase levels. Etiologies include autoantibodies against HMGCR or SRP antigens. Pathophysiology involves complement-mediated myofiber necrosis with minimal inflammatory infiltrate. Diagnosis is based on clinical findings, serologic testing, electromyography, and muscle biopsy. Management involves immunosuppressive therapy, including corticosteroids, intravenous immunoglobulin, and steroid-sparing agents; prognosis varies, with early intervention improving outcomes.