Dermatomyositis (3)

Question 1

What is it?

What are its features?

Answer 1

➊ Chronic inflammation of skin and muscles

➋ Presents with the features of Polymyositis (bilateral, proximal muscle weakness, pain, and fatigue) + Skin features:
* Heliotrope rash (lilac discolouration of eyelid with periorbital oedema)
* Gottron lesions (scaly erythematous patches) on joints
* Macular erythematous rash

Question 2

Investigations:
What is the key investigation finding here?
→ What are other causes of this being raised?

What other investigations may be done?

What is done for a definitive diagnosis?
→ What will this show?

Answer 2

➊ Raised CK
→ Rhabdomyolysis, AKI, MI, Statins, Strenuous exercise

➋ * EMG – Confirms myopathic cause, and excludes a neuropathic cause
* Anti-Jo-1, Anti-Mi-2

➌ Muscle biopsy
→ Inflammatory infiltrates

Question 3

What is used to manage it?
→ What may be added alongside this? How does this help?

Answer 3

Corticosteroids
→ Immunosuppressants/DMARDs e.g. methotrexate – This makes it easier for the steroids to work, therefore not needing as high a dose