[Idiopathic inflammatory myopathies. A review]

Area of Science:

• Rheumatology
• Neurology
• Immunology

Background:

• Idiopathic inflammatory myopathies (IIM) encompass a diverse range of acquired immune-mediated conditions affecting skeletal muscle.
• Clinical presentation includes proximal muscle weakness, elevated muscle enzymes, electromyography abnormalities, and characteristic muscle biopsy findings.
• IIM classification includes dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), and immune-mediated necrotizing myopathy (IMNM), distinguished by histopathology.

Purpose of the Study:

• To review the classification, clinical features, and treatment strategies for idiopathic inflammatory myopathies.
• To highlight the association of myositis-specific antibodies with distinct phenotypes and risks.
• To discuss the prognostic implications and causes of mortality in IIM.

Main Methods:

• Literature review of idiopathic inflammatory myopathies.
• Analysis of classification criteria based on histopathology.
• Summary of current and emerging therapeutic approaches.

Main Results:

• Myositis-specific antibodies correlate with specific IIM phenotypes and associated risks (neoplasia, systemic complications).
• Immunosuppression is the cornerstone for treating DM, PM, and IMNM; IBM management is primarily symptomatic.
• Steroids and other immunosuppressants are first-line treatments, with biologics offering future personalized therapies.

Conclusions:

• The 10-year survival for DM, PM, and IMNM ranges from 62% to 90%, with neoplastic and cardiorespiratory complications being leading causes of death.
• IBM significantly impacts quality of life but does not typically affect survival.
• Understanding IIM subtypes and associated antibodies is crucial for guiding treatment and predicting outcomes.