Rare forms of inflammatory myopathies - part I, generalized forms

Area of Science:

• Neurology
• Rheumatology
• Immunology

Background:

• Idiopathic inflammatory myopathies (IIMs) traditionally include dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, anti-synthetase syndrome, and inclusion body myositis.
• This review focuses on the less common, generalized forms of myositis, expanding beyond the well-established classifications.

Approach:

• Identified rare generalized myopathies using resources from Washington University's Neuromuscular disease center and expert knowledge.
• Conducted a literature search of PubMed® and EMBASE® for relevant articles on these rare myopathies.

Key Points:

• Rare myopathies exhibit significant heterogeneity in frequency and characterization.
• Some rare forms are well-defined, while others may represent variants of more common myopathies.
• Emerging forms, like SARS-CoV-2- and immune checkpoint inhibitor-related myositis, highlight the evolving landscape of these conditions.

Conclusions:

• Knowledge of rare myositis forms is essential for their recognition and appropriate management.
• This review provides clinical insights and guidance for the work-up and treatment of uncommon generalized myopathies.