Polymyositis & Dermatomyositis

Question 1

What are polymyositis and dermatomyositis?

Answer 1

• Rare autoimmune connective tissue diseases

Question 2

What are the characteristics of polymyositis and dermatomyositis?

Answer 2

• Insidious onset of progressive symmetrical proximal muscle weakness and autoimmune-mediated striated muscle inflammation

Question 3

What are the symptoms of polymyositis and dermatomyositis?

Answer 3

• Muscle weakness may also cause dysphagia, dysphonia or respiratory weakness
• The myositis may be a paraneoplastic phenomenon so screen for cancers

Question 4

What is the difference between polymyositis and dermatomyositis?

Answer 4

Dermatomyositis is myositis plus skin signs:

• Macular rash
• Lilac purple rash on eyelids
• Nailfold erythema
• Malignancy in 30% of cases

Question 5

What are the extra-muscular signs of polymyositis and dermatomyositis?

Answer 5

• Fever
• Arthralgia
• Raynauds
• Interstitial lung fibrosis
• Myocardial involvement

Question 6

What tests are used for polymyositiis and dermatomyositis?

Answer 6

• Muscle enzymes raised in plasma
  
  • ALT
  • AST
  • LDH
  • CK
  • Aldolase
• Autoantibody associates
• MRI shows muscle oedema in acute myositis

Question 7

How is polymyositis and dermatomyositis managed?

Answer 7

• Prednisolone
• Immunosuppressives and cytotoxics
  
  • Used early in resistant cases
• Hydroxychloroquine/topical tacrolimus for skin disease