Immune-Mediated Necrotizing Myopathy: A Review for Clinicians

Immune-mediated necrotizing myopathy (IMNM) is a group of inflammatory myopathies showing necrotic and regenerating fibers without noteworthy inflammatory cell infiltration on pathology. The pathologic findings are different from those of dermatomyositis or sporadic inclusion body myositis. Furthermore, the discovery of myositis-specific antibodies in patients with IMNM, such as anti-signal recognition particle or anti-3-hydroxy-3-methylglutaryl-CoA reductase antibodies, has enabled us to expand our knowledge of IMNM. However, the phenotype and pathological findings of IMNM are unremarkable; therefore, it is difficult to diagnose, and IMNM has been relatively unrecognized. In this review, we introduce the clinical features, diagnosis, pathomechanism, and treatment of IMNM for clinicians.