Polymyositis and dermatomyositis Flashcards
What is the primary characteristic of Polymyositis and Dermatomyositis?
Both are autoimmune disorders that cause muscle inflammation (myositis) and present with proximal muscle weakness.
How do Polymyositis and Dermatomyositis differ in terms of skin features?
Polymyositis occurs without skin features.
Dermatomyositis involves characteristic skin changes such as Gottron papules and heliotrope rash.
What are Gottron papules, and where are they found in Dermatomyositis?
Gottron papules are scaly erythematous patches found on the knuckles, elbows, and knees in Dermatomyositis.
What is a heliotrope rash, and where is it found?
A heliotrope rash is a purple rash on the face and eyelids, commonly associated with Dermatomyositis.
What are some other skin features of Dermatomyositis?
- Periorbital oedema (swelling around the eyes)
- Photosensitive erythematous rash on the back, shoulders, and neck
What is the typical presenting symptom of Polymyositis and Dermatomyositis?
Gradual-onset, symmetrical, proximal muscle weakness, causing difficulty standing from a chair, climbing stairs, or lifting overhead.
What is the critical test for diagnosing myositis (Polymyositis and Dermatomyositis)?
The creatine kinase (CK) blood test. Elevated CK levels indicate muscle inflammation.
What are other causes of raised creatine kinase levels?
- Rhabdomyolysis
- Acute kidney injury
- Myocardial infarction
- Statins
- Strenuous exercise
What diagnostic tests are used to confirm Polymyositis or Dermatomyositis?
- Clinical features
- Elevated creatine kinase
- Autoantibodies
- Electromyography (EMG)
- Magnetic resonance imaging (MRI)
- Muscle biopsy
Which autoantibody is most commonly associated with Polymyositis?
Anti-Jo-1 antibodies are most commonly associated with Polymyositis.
How is Polymyositis and Dermatomyositis typically managed?
- Corticosteroids are the first-line treatment for both conditions.
- If the response to steroids is inadequate, additional treatments include:
- Immunosuppressants (e.g., methotrexate or azathioprine)
- IV immunoglobulins
- Biological therapy (e.g., infliximab or etanercept)
What additional management may benefit patients with Polymyositis and Dermatomyositis?
Physiotherapy and occupational therapy to help with muscle strength and function.
Why is it important to assess new cases of Polymyositis and Dermatomyositis for underlying cancer?
Polymyositis and Dermatomyositis can be paraneoplastic syndromes, meaning they may be caused by an underlying cancer.
