Polymyositis and Dermatomyositis

Question 1

What is polymyositis and Dermatomyositis?

Answer 1

autoimmune inflammatory disorder which causes symmetrical, proximal (striated) muscle weakness

Polymyositis - affects just muscles

Dermatomyositis - affects muscles and skin

Question 2

Who does polymyositis and dermatomyositis commonly affect?

Answer 2

middle aged

female: male 3:1

Question 3

What are polymyositis and dermatomyositis associated with?

Answer 3

malignancy- can be caused by an underlying cancer which means it is a parenoplastic syndrome

main ones:
Breast
Lung
Ovarian
Bowel

Question 4

What is the common presentation of polymyositis and dermatomyositis

Answer 4

Both Polymyositits and Dermatomyositis

• muscle pain, weakness and fatigue, affecting proximal muscles
• muscle weakness can cause dysphagia and dysphonia
• can cause respiratory muscle weakness

Skin features only in dermatomyositis

Question 5

Which features are exclusive to dermatomyositis?

Answer 5

1. Gottron’s papules: roughened red papules over knuckles, elbows and knees
2. Macular rash (shawl sign) over back and shoulders
3. photosensitive
4. lilac purple (heliotrope) rash on eyelids, often with oedema (periorbital oedema)
5. Nailfold erythema (capillary dilation)

Question 6

What is pathognomonic of Dermatomyositis?

Answer 6

1. Gottron’s papules
2. Increased creatinine kinase
3. Muscle weakness

Question 7

How do you diagnose polymyositis and dermatomyositis

Answer 7

• clinical presentation
• elevated creatinine kinase (more than 1000)
• Autoantibodies
• EMG
• muscle biopsy can be done for definitive diagnosis

Question 8

Which autoantibodies are associated with polymyositis and dermatomyositis?

Answer 8

Anti Jo-1 - Polymositis
Anti M2 - Dermatomyositis
ANA - Dermatomyositis

Question 9

What are other causes of raised creainine kinase besides polymyositis and dermatomyositis

Answer 9

Rhabdomyolysis
Acute kidney injury
Myocardial infarction
Statins
Strenuous exercise

Question 10

What is the management of dermatomyositis and polymyositis?

Answer 10

• assess for underlying cancer
• physiotherapy, occupational therapy
• corticosteroids - prednisolone
• immunosuppresants (aza),biologics - infliximab