The Utility of Myositis Specific Antibodies in Clinical Practice

Fifteen myositis-specific antibodies have been described and characterized over the past 40 years. Approximately two thirds of patients with idiopathic inflammatory myositis have a myositis-specific antibody and only rarely more than one. Assays to detect them are now widely available within clinical practice.

We describe the original description and clinical phenotype of the myositis-specific antibodies, forming the antisynthetase syndrome group, anti-MDA-5 and rapidly progressive interstitial lung disease, anti-SRP/HMGCR and necrotizing myositis, anti-TIF-1γ/NXP-2 and malignancy, anti-SAE and esophageal disease, and anti-Mi-2 and classic dermatomyositis skin disease.

Clinical practice is likely to be refined, with diagnosis and classification of the idiopathic inflammatory myositides based primarily on myositis-specific antibody, rather than directed by muscle histology or the broader clinical characteristics of polymyositis and dermatomyositis. All patients newly presenting with idiopathic inflammatory myositis should be routinely screened for myositis-specific antibodies. A positive result will usefully provide diagnostic and prognostic information, guide selection of therapy, and prompt surveillance for potential organ involvement and other features, such as cancer, throughout the disease course.