Inflammatory myopathies (IM), also known as myositis, are rare autoimmune diseases that primarily affect skeletal muscles but can also involve the skin, lungs, and heart. They are classified into dermatomyositis, overlap myositis, antisynthetase syndrome (ASyS), immune-mediated necrotizing myopathy (IMNM), and sporadic inclusion body myositis (sIBM). Diagnosing IM requires a combination of clinical evaluation, muscle biopsy, MRI, serologic assessments, and electromyography. Identification of myositis-specific autoantibodies helps classify patients into homogeneous subtypes, each with distinct clinical phenotypes and associated risks, such as interstitial lung disease (ILD) and cardiac involvement.

Management and treatment of IM depend on early and accurate diagnosis, which can be challenging due to overlapping symptoms with other conditions. Specific autoantibodies, such as anti–Mi-2, anti-NXP2, anti-TIF1γ, and anti-MDA5, are linked to particular forms of myositis and guide treatment decisions. Studies have shown that targeted therapies based on these autoantibodies can improve patient outcomes. However, there is a need for ongoing research to better understand disease mechanisms and develop new therapeutic targets, particularly for cases classified as antibody-negative dermatomyositis and IMNM.

Reference: Jammal C, Pinal-Fernandez I, Mammen A. Adult Inflammatory Myopathies: Updates on Classification and Management. Practical Neurology. Accessed June 27, 2024.