Advances in study on diagnosis and treatment of immune-mediated necrotizing myopathy

Abstract

Immune-mediated necrotizing myopathy (IMNM) is a significant, subtype of idiopathic inflammatory myopathy（IIM）, characterized by symmetrical proximal limb muscle weakness and markedly elevated serum creatine kinase levels. Some patients may also exhibit extra-skeletal muscle manifestations, including rashes, interstitial lung disease, and myocardial involvement. Since its international nomenclature in 2003, IMNM has gained increasing recognition among researchers and clinicians, leading to numerous scientific investigations and clinical applications. The incidence and prevalence of IMNM can vary across different geographic regions and ethnic groups. A small sample survey conducted in the United States reported an incidence of 0.83 per 100,000 and a prevalence of 1.85 per 100,000. In northern Spain, among patients positive for anti-HMGCR antibodies, the incidence was found to be 0.6 per 100,000, with a prevalence of 3 per 100,000. However, there is a notable paucity of relevant data regarding IMNM in China. Identified risk factors for IMNM include susceptibility alleles (e.g., HLA-DRB1*11), the use of statins or immune checkpoint inhibitors, and viral infections. Diagnosing IMNM requires a comprehensive evaluation that includes assessing muscle involvement symptoms, identifying myositis-specific autoantibodies, measuring creatine kinase levels, analyzing muscle biopsy pathology, and conducting related examinations. Currently, there is a lack of prospective randomized controlled studies on the treatment of IMNM. In clinical practice, glucocorticoids and traditional immunosuppressants are primarily employed on an empirical basis. For refractory cases, treatment regimens may involve rituximab and intravenous human immunoglobulin. Therapeutic strategies targeting B cells and the mechanisms underlying pathogenic autoantibody production may offer promising avenues for future treatment. This article systematically reviews the clinical characteristics, diagnostic criteria, relevant auxiliary examinations, and treatment strategies for IMNM, aiming to provide a comprehensive reference for clinicians in understanding, diagnosing, and managing this condition.

Keywords

• |immune mediated necrotizing myopathy|myositis specific antibodies|targeted therapy