Dermatomyositis and polymyositis

Polymyositis is an idiopathic inflammatory disorder of skeletal muscle. When it is associated with cutaneous lesions it is dermatomyositis.

  • Progressive proximal muscle weakness
  • Dysphonia
  • Dysphagia
  • Fever
  • Arthralgia/arthritis
  • Muscle pain
  • More rarely respiratory muscle weakness

Possible complications:
  • Cardiomyopathy
  • Intersitial lung disease
  • Malignancy – commonest in dermatomyositis; most frequently lymphoma or ovarian or gastric cancer

Skin signs:
  • Pathognomonic
    • Gottron’s papules = erthematous papules over IP/MCP/elbow/knee joints
    • Gottron’s sign = macules/plaques in same distribution as Gottron’s papules
  • Non-pathognomic signs
    • Heliotrope (liliac-purple) rash around eyelids/cheeks
    • Shawl sign = macular rash over back and shoulders
    • Periungal telangectasia

  • Raised CK/AST/ALT/LDH
  • Raised ANA in 60-80%
  • Anti-Jo antibodies in 20% of dermatomyositis
  • Abnormal EMG

Treatment is:
  • Prednisolone
  • Methotrexate/cyclosporin
  • Screen for malignancy

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Secret collector of interesting anonymised ECGs. Fan of the Bath Photomarathon. Lover of cream teas. [Sarah Hudson] (Your Picture)