Polymyositis and Dermatomyositis

Question 1

What do polymyositis and dermatomyositis have in common?

Answer 1

Autoimmune disorders where there is inflammation in the muscles.

Question 2

What is the difference between polymyositis and dermatomyositis?

Answer 2

1. Polymyositis - chronic muscle inflammation

2. Dermatomyositis - connective tissue disorder where the skin is also involved

Question 3

What is the key investigation for diagnosing myositis?

Answer 3

Creatine kinase - over 1000 U/L in myositis

Question 4

What are the main causes of a raised creatine kinase?

Answer 4

1. Myositis
2. Rhabdomyolysis
3. AKI
4. MI
5. Statins
6. Strenuous exercise

Question 5

Which cancers are commonly associated with myositis?

Answer 5

Lung, breast, ovarian, gastric.

Question 6

What is this a presentation of?

Muscle pain, fatigue, and weakness occurring bilaterally and affecting proximal muscles, developed over weeks.

Answer 6

Polymyositis

Question 7

What are the skin features found in dermatomyositis?

Answer 7

1. Gottron lesions on knuckles, elbows, knees
2. Photosensitive erythematous rash on back, shoulders, and neck
3. Purple rash on face and eyelids
4. Periorbital oedema
5. Subcutaneous calcinosis

Question 8

What are Gottron lesions and what condition are they found in?

Answer 8

1. Scaly erythematous patches

2. Dermatomyositis

Question 9

Which conditions are Anti-Jo antibodies found in?

Answer 9

Polymyositis and dermatomyositis

Question 10

What condition are Anti-Mi-2 and Anti-nuclear antibodies found in?

Answer 10

Dermatomyositis

Question 11

How are polymyositis and dermatomyositis diagnosed?

Answer 11

Clinical presentation, creatine kinase, autoantibodies, electromyography, muscle biopsy for definitive diagnosis.

Question 12

What are the treatment options for polymyositis and dermatomyositis?

Answer 12

1. Corticosteroids 1st line for both

2. Immunosuppressants (azathioprine), IV immunoglobulins, biological therapy (infliximab/etanercept)