Dermatomyositis case

Question 1

What are the signs and symptoms of DM

Answer 1

Symmetrical muscle weakness in proximal limbs

Photosensitive rash on shoulders, neck
Scaly patches on knuckles, elbows, knees
Red/purple rash with swelling on upper eyelid
Eye edema

Question 2

What is the pathophysiology of DM?

Answer 2

AI muscle and skin disease => inflammation of skeletal muscles involved in voluntary movement

Question 3

What investigations would you order

Answer 3

FBC, U&E, CRP, ESR
-all normal => rule out rhabdomyolysis (also presents with proximal muscle weakness)

CK, aldolase, LDH transaminase (skeletal muscle enzymes)
-elevated

AST, ALT
-liver transaminases may also be elevated with skeletal muscle enzymes

Autoantibodies
-ANA => rule out lupus, sjogrens

Question 4

What would you find on neuro examination

Answer 4

Normal cranial nerves

Symmetrical weakness in neck, hips, shoulder flexors

Sensation ok

Question 5

What scans would you also order

Answer 5

CXR
-DM sometimes presents with ILD

Screen for cancer
-associated with malignancy

Question 6

How would you manage DM

• acutely
• chronic

Answer 6

Acute

• Corticosteroids
• IV immunoglobulins

Chronic

• DMARDs
• suncream
• physical, speech therapy