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Differences in clinical features and prognosis of interstitial lung diseases between polymyositis and dermatomyositis

Tomoyuki Fujisawa1, Takafumi Suda, Yutaro Nakamura

  • 1Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan.

The Journal of Rheumatology
|January 5, 2005
PubMed
Abstract

Insights

Patients with dermatomyositis-associated interstitial lung disease (DM-ILD) face a poorer prognosis and are more resistant to corticosteroid treatment than those with polymyositis-associated interstitial lung disease (PM-ILD). Intensive therapies like cyclosporine may be beneficial for DM-ILD.

Area of Science:

  • Rheumatology
  • Pulmonology
  • Immunology

Background:

  • Interstitial lung disease (ILD) is a significant complication in patients with idiopathic inflammatory myopathies, particularly polymyositis (PM) and dermatomyositis (DM).
  • Understanding the distinct clinical features and prognoses of ILD in PM versus DM is crucial for effective patient management.

Purpose of the Study:

  • To compare the clinical characteristics and outcomes of interstitial lung disease in patients diagnosed with polymyositis versus dermatomyositis.
  • To identify potential differences in treatment response and survival rates between PM-ILD and DM-ILD.

Main Methods:

  • Retrospective review of medical records for 28 patients with ILD and either PM or DM (16 PM-ILD, 12 DM-ILD).
  • Analysis included serum creatine phosphokinase (CPK) levels, bronchoalveolar lavage (BAL) findings, and histopathological examination (surgical lung biopsy or autopsy).
  • Evaluation of treatment responses to corticosteroids and cyclosporine, and assessment of patient survival.

Main Results:

  • Serum CPK levels were higher in PM-ILD than DM-ILD. BAL analysis revealed higher lymphocyte and eosinophil percentages in DM-ILD.
  • Histopathology showed nonspecific interstitial pneumonia (NSIP) in 7 patients and usual interstitial pneumonia (UIP) in 3. Diffuse alveolar damage (DAD) was observed in 3 fatal DM-ILD cases, but not in PM-ILD.
  • Corticosteroid monotherapy was effective in 37.5% of PM-ILD cases versus only 8.3% of DM-ILD cases. Cyclosporine benefited 4 corticosteroid-resistant DM-ILD patients.

Conclusions:

  • Dermatomyositis-associated ILD (DM-ILD) demonstrates greater refractoriness to corticosteroid therapy and a significantly worse prognosis compared to polymyositis-associated ILD (PM-ILD).
  • These findings suggest that more intensive therapeutic strategies, potentially including early administration of agents like cyclosporine, should be considered for patients with DM-ILD to improve outcomes.

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