anti-synthetase syndrome
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Etiology
* not seen in patients with inclusion body myositis[6]
Epidemiology
- rare
- more prevalent in women than in men
Pathology
- autoantibody against tRNA synthetases
- anti-Jo1 Ab is most common antibody
Clinical manifestations
- interstitial lung disease (may be only manifestation)
- inflammatory myopathy
- proximal muscle weakness (hips, shoulders)
- difficulty raising head
- difficulty standing from sitting
- symmetric inflammatory polyarthritis affecting small joints
- variable features include
- low-grade fever
- Raynaud's phenomenon
- mechanics hands[3]
- disease may be slowly progressive
- intermittent relapses may occur
Laboratory
- serum creatine kinase is often elevated (as high as 20,000 IU/L[3]
- anti-Jo1 Ab in serum may be positive
- anti-SSA Ab in serum may be positive
- antinuclear antibody may be high titer
- always check serum TSH when evaluating myopathy
Diagnostic procedures
- electromyography may be abnormal
- muscle biopsy may be abnormal
- pulmonary function testing may be abnormal
- lung biopsy
- swallowing study as indicated
Radiology
- chest X-ray
- high-resolution CT of lungs
- characteristic of interstitial lung disease
- lower lobe predominantly peripheral ground-glass opacities
- subpleural reticulation
- traction bronchiectasis
- characteristic of interstitial lung disease
- MRI of thorax as indicated
Complications
Management
- see specific etiology
- glucocorticoids*
- other immunosuppressive agents
- azathoprine*
- methotrexate
* prednisone 60 mg PO QD + azathioprine 150 mg PO QD
* prednisone alone (NEJM)[7]
More general terms
References
- ↑ Wikipiedia: Antisynthetase syndrome https://en.wikipedia.org/wiki/Antisynthetase_syndrome
- ↑ Christopher-Stine L, Robinson DR, Wu CC, Mark EJ. Case records of the Massachusetts General Hospital. Case 37-2012. A 21-year-old man with fevers, arthralgias, and pulmonary infiltrates. N Engl J Med. 2012 Nov 29;367(22):2134-46 PMID: https://www.ncbi.nlm.nih.gov/pubmed/23190225
- ↑ 3.0 3.1 3.2 Chatterjee S, Prayson R, Fraver C. Antisynthetase syndrome: Not just an inflammatory myopathy. Cleveland Clinic Journal of Medicine 2013;80:655-666. PMID: https://www.ncbi.nlm.nih.gov/pubmed/24085811
Chatterjee S Mechanic's Hands N Engl J Med 2021; 384:e16. Feb 11 PMID: https://www.ncbi.nlm.nih.gov/pubmed/33567195 https://www.nejm.org/doi/full/10.1056/NEJMicm2026773 - ↑ Lazarou IN, Guerne PA Classification, diagnosis, and management of idiopathic inflammatory myopathies. J Rheumatol. 2013 May;40(5):550-64 PMID: https://www.ncbi.nlm.nih.gov/pubmed/23504386
- ↑ Lega JC, Fabien N, Reynaud Q et al The clinical phenotype associated with myositis-specific and associated autoantibodies: a meta-analysis revisiting the so-called antisynthetase syndrome. Autoimmun Rev. 2014 Sep;13(9):883-91. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/24704867
- ↑ 6.0 6.1 Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
- ↑ 7.0 7.1 NEJM Knowledge+