Dermatomyositis

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Background

  • Inflammatory myopathy with skin manifestations
  • Affects proximal muscles > distal
  • Female:Male; 2:1
  • Peak incidence 40-50s

Clinical Features

Heliotrope rash

Muscular

  • Symmetric weakness
  • Proximal greater than distal weakness
    • Deltoid and hip flexors
    • difficulty standing from a chair
  • Onset over months
  • Mild myalgias

Dermatologic

  • Heliotrope rash on face scalp
  • Gottron's papules (rash on MCP, PIP, and DIP joints)
  • Shawl sign (rash above shoulders)

Other

  • Cardiac (cardiomyopathy)
  • High association with malignancy
  • Interstitial lung disease
  • Esophageal inflammation

Differential Diagnosis

  • Drug Induced Myopathies (Statins)

Weakness

Evaluation

  • CK
  • ANA
  • Anti-Jo-1
  • Chem for creatinine
  • Troponin, can involve myocardium
  • ECG
  • Bedside PFTs (FEV1 and FVC)
  • Urinalysis for myoglobin
  • EMG or muscle biopsy showing myositis
  • Consider malignancies
    • Associated with increased age, male gender and elevated creatinine kinase levels
  • Signs of systemic inflammation[1]
    • Fever
    • ESR elevated in 50% of patients, does not correlate with disease activity
    • Elevated CRP

Management

Mild disease

  • Prednisone 1mg/kg/day (up to 80mg/day)
    • Taper after 6-8 weeks

Severe disease

  • Interstitial Fibrosis or weakness of respiratory muscles
    • Presents with breathlessness, respiratory insufficiency
    • Associated with presence of anti-Jo1 antibody[2]
    • Increased risk of aspiration, which is a leading cause of death in patients with restricted mobility[3]
    • Poor prognosis
    • Methylprednisolone 1000mg/day x 3 days
  • Cardiac Myositis
    • Presents with known Dermatomyositis and mild rhythm disturbances, CHF or myocardial fibrosis
    • Causes include reentry pathways, fibrosis, altered automaticity, conduction system injury or treatment side effects

Disposition

  • Admit to monitored bed for CHF symptoms, respiratory muscle weakness
  • Admit for dysphagia/aspiration risk
  • Out patient follow up with muscle biopsy for others
  • Very strongly associated with malignancy (~30%), especially:[4]
    • Ovarian
    • Lung
    • Pancreatic
    • Stomach
    • Colorectal
    • Non-Hodgkin Lymphoma
    • Bladder

See Also

References

  1. Koler RA and Montemarano A. Dermatomyositis. Am Fam Physician. 2001 Nov 1;64(9):1565-1573.
  2. Vymetal J, Skacelova M, Smrzova A, Klicova A, Schubertova M, Horak P, Zadrazil J. Emergency situations in rheumatology with a focus on systemic autoimmune diseases. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2016 Mar;160(1):20-9. doi: 10.5507/bp.2016.002. Epub 2016 Feb 10. Review. PubMed PMID: 26868300.
  3. Fujisawa T, Hozumi H, Kono M, Enomoto N, Hashimoto D, Nakamura Y, Inui N, Yokomura K, Koshimizu N, Toyoshima M, Shirai T, Yasuda K, Hayakawa H, Suda T. Prognostic factors for myositis-associated interstitial lung disease. PLoS One [serial on the internet] 2014 Jun [cited 2014 Oct 20]; Available from: http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC4048238/?report=classic
  4. Hill CL et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100.