Polymyositis & Dermatomyositis

Question 1

What is polymyositis and dermatomyositis?

Answer 1

AI disorders where there is inflammation in the muscles (myositis)

Question 2

What is polymyositis?

Answer 2

Chronic inflammation of muscles

Question 3

What is dermatomyositis?

Answer 3

Connective tissue disorder where there is chronic inflammation of skin & muscles

Question 4

What can cause these conditions?

Answer 4

Can be caused by underlying malignancy

Question 5

What does being caused by underlying malignancy make these disorders?

Answer 5

Paraneoplastic syndromes

Question 6

Most common associated cancers with these diseases?

Answer 6

Lung
Ovarian
Breast
Gastric

Question 7

Presentation of dermatomyositis and polymyositis?

Answer 7

• Muscle pain, fatigue & weakness
• Bilaterally & typically & proximal muscles
• Mostly affects shoulder & pelvic girdle
• Develops over weeks

Question 8

Which one of these conditions has skin features?

Answer 8

Dermatomyositis

Question 9

What are the skin features of dermatomyositis?

Answer 9

• Gottron lesions
• Photosensitive
• Purple rash on face/eyelids
• Periorbital oedema
• SC Calcinosis

Question 10

What are Gottron lesions?

Answer 10

Scaly erythematosus patches

-on knuckles, elbows and knees

Question 11

Auto-antibodies associated with polymyositis?

Answer 11

Anti-Jo-1 ABs (often also present in dermatomyositis)

Question 12

Auto-antibodies associated with dermatomyositis?

Answer 12

• Anti-Mi-2 ABs

- Anti-nuclear ABs

Question 13

What is the diagnosis of these diseases based on?

Answer 13

Clinical presentation 
Elevated CK 
Auto-ABs 
Muscle biopsy 
Electromyography (EMG)

Question 14

Additional management of polymyositis and dermatomyositis?

Answer 14

• Assess for possible underlying cancer

- May require physio

Question 15

Medical management of the myositises?

Answer 15

Corticosteroids = 1st line

Other options:

• Immunosuppressants
• IV Immunoglobulins
• Biological Therapy