[Inflammatory myopathies: diagnosis and classifications].

Area of Science:

• Neurology
• Immunology
• Pathology

Context:

• Idiopathic inflammatory myopathies (IIMs) are a group of rare autoimmune diseases affecting muscles.
• Accurate classification and understanding of IIM subtypes are essential for effective management.

Purpose:

• To delineate the five major types of idiopathic inflammatory myopathies: dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), autoimmune necrotizing myopathy (AINM), and overlap myositis.
• To describe the distinct clinical manifestations, histological features, and treatment responses of each IIM subtype.

Summary:

• DM, PM, and AINM present with subacute, proximal, symmetrical weakness and respond to immunosuppressants, with DM having characteristic skin involvement.
• IBM features late-onset, distal muscle weakness, unresponsive to immunosuppressants, and is histologically defined by rimmed vacuoles.
• Specific autoantibodies, such as anti-synthetase and anti-SRP, are associated with distinct clinical syndromes, including interstitial lung disease and rapid progression, respectively.
• Inflammatory myopathies associated with connective tissue diseases (CTD) are heterogeneous and require further characterization.

Impact:

• Provides a comprehensive overview of IIM classification, aiding clinicians in diagnosing and managing these complex conditions.
• Highlights the prognostic implications, such as increased malignancy risk in DM and AINM.
• Emphasizes the need for further research into the heterogeneous category of overlap myositis.