amyopathic dermatomyositis; dermatomyositis-sine-myositis

Etiology

• cormidities common
  • lung disease 19%, 39% of these fatal
  • malignancies 14%
    • nasopharyngeal carcinoma, breast cancer, ovarian cancer
• may be triggered by sunlight

Epidemiology

• 20-30% of patients with dermatomyositis

Pathology

• histopathologic myositis may or may not be present

Clinical manifestations

• skin lesions characteristic of dermatomyositis
• delayed or absent muscle involvement

Laboratory

• anti-nuclear antibody present in 63%
• anti Jo-1 antibody uncommon
• serum muscle enzymes may be elevated
  • serum creatine kinase
    • CKMB index may be elevated by regenerating skeletal muscle
  • serum lactate dehydrogenase
  • serum aldolase
  • serum aspartate transaminase (serum AST)
• CADM-140 autoantigen (IFIH1)
  • patients with anti-CADM-140 antibodies frequently develop life-threatening acute progressive interstitial lung disease

Diagnostic procedures

• electromyography normal or may be abnormal
• pulmonary function testing with DLCO
  • evaluate for interstitial lung disease
• evaluate for malignancy

Complications

• pulmonary: interstitial lung disease
• malignancy
• see dermatomyositis

Management

• glucocorticoids
• immunosuppressive agents

Notes

see dermatomyositis

More general terms

• dermatomyositis