Antibodies in inflammatory myositis
Myositis-specific versus myositis-associated antibodies, why the ANA can be negative, how to read a line blot (band strength, one MSA per patient, matching the HEp-2 pattern), anti-HMGCR by ELISA, and the results that change management today (MDA5, TIF1-gamma and NXP2, HMGCR, SRP).
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The myositis antibody profile sorts inflammatory myopathy into phenotypes with different organ risks, cancer risk and treatment. It now carries as much weight as the biopsy in many patients.
- Request it with ANA and ENA in anyone with unexplained proximal weakness and raised CK, a dermatomyositis rash, ILD with mechanic's hands or Raynaud, or necrotising myopathy on biopsy.
- A negative ANA does not exclude myositis. Several key antibodies are cytoplasmic or weakly staining.
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Sources
- Therapeutic Guidelines: Rheumatology (inflammatory myopathies)AU/NZTherapeutic Guidelines Limited, current online version, accessed November 2026
- RCPA Manual: myositis antibodies and HMG-CoA reductase antibodiesAU/NZRoyal College of Pathologists of Australasia, online, accessed November 2026
- Lundberg IE et al. 2017 EULAR/ACR classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis 2017;76:1955-64EULAR and ACR, 2017 (still current in November 2026; a revision is in development)
- Allenbach Y et al. 224th ENMC international workshop: clinico-sero-pathological classification of immune-mediated necrotizing myopathies. Neuromuscul Disord 2018;28:87-99European Neuromuscular Centre, 2018
- Oldroyd AGS et al. International guideline for idiopathic inflammatory myopathy-associated cancer screening: an IMACS initiative. Nat Rev Rheumatol 2023;19:805-17International Myositis Assessment and Clinical Studies Group, 2023
- Damoiseaux J et al. Clinical relevance of HEp-2 indirect immunofluorescent patterns: the International Consensus on ANA patterns (ICAP) perspective. Ann Rheum Dis 2019;78:879-89Annals of the Rheumatic Diseases, 2019
- Betteridge Z, McHugh N. Myositis-specific autoantibodies: an important tool to support diagnosis of myositis. J Intern Med 2016;280:8-23Journal of Internal Medicine, 2016
- Last updated
- 14 November 2026
What changed
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