2017 Volume 33 Issue 6 Pages 627-632
Immune–mediated necrotizing myopathy (IMNM) is recently defined subgroup of idiopathic inflammatory myopathies. IMNM is characterized by significant necrosis, with muscle fiber regeneration, but without or with little inflammatory cells on muscle biopsy. IMNM may be associated with myositis–specific autoantibodies against signal recognition particle (SRP), or against 3–hydroxy–3–methylglutaryl–coenzyme A reductase (HMGCR). Typical clinical features such as severe muscle weakness, highly elevated serum creatine kinase (CK) levels, as well as resistance to conventional immunosuppressive therapy. Severe limb muscle weakness, neck weakness, dysphagia, respiratory insufficiency and muscle atrophy were more frequently observed in patients with anti–SRP antibodies than that in with anti–HMGCR antibodies. The pathophysiological mechanisms of these diseases are poorly understood, and therapeutic strategies for treating patients have not yet been validated. Most patients in both types were initially treated with corticosteroids. Additional immunotherapies were needed in patients with anti–SRP antibodies. In addition, one third of IMNM therapy do not show known specific autoantibodies. This review provides an overview of this disease entity and focuses on its clinical features and immunotherapy.
