Myositis

Question 1

What are Dermatomyositis and Polymyositis?

Answer 1

Rare idiopathic muscle diseases that are

characterized by inflammation of striated muscle.

Question 2

How does myositis present?

Answer 2

Insidious onset of proximal muscle weakness, often painless.
Presentation way be with SOB or rash.
Raynaud’s is also common.

Question 3

What antibody tests can be done in myositis?

Answer 3

80% patients are antinuclear antibody positive.
Specific auto-antibodies are increasingly being
discovered and include anti-Jo-1 and anti-Mi2

Question 4

How is myositis treated?

Answer 4

High dose corticosteroids.
Monitoring with inflammatory marker and CK. Repeat
EMG studies/MRI or biopsy may be needed.
Long term control is with MTX or AZA. Rituximab can be effective. Intravenous immunoglobulin is also
effective.
In dermatomyositis, sun protection is important t and HCQ may reduce rash.