Dermatomyositis
(Idiopathic Inflammatory Myopathy)
Pronounced: Der-MAA-toe-MY-oh-SI-tis
Causes
The exact cause of dermatomyositis is not known. It may be an autoimmune disorder. The immune system identifies and attacks viruses and bad bacteria in your body. An autoimmune disorder means the immune system begins to attack normal healthy tissue.
A viral infection may trigger the onset of dermatomyositis.
Risk Factors
Your chance of developing dermatomyositis is higher if you have a connective tissue disorder such as:
Symptoms
Dermatomyositis may cause:
-
Skin changes such as:
- Violet-colored, bumpy, or scaly skin rash (especially around the eyes, upper back, elbows, or knuckles)
- Itching, especially the scalp
- Sensitivity to sunlight
- Calcium deposits
-
Muscle
problems such as:
- Weakness especially in hips, thighs, arms or neck
- Aching pain in legs, shoulder, arm, or neck
- Tender muscles
- Difficulty swallowing and speaking
- Aching and color changes (red, white, and blue) in fingers, especially in cold temperatures
- Joint pain
- Shortness of breath
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Diagnosis
Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may be referred to a specialist for further evaluation.
Blood tests may be done to look for infections or signs of muscle damage and inflammation. Your doctor may also do a series of tests on the muscle including:
- Electromyogram (EMG) —to test muscle activity
- Muscle biopsy —to take a sample of muscle tissue
- Magnetic resonance imaging (MRI) or ultrasound—to detect inflammation in your muscles.
Other tests that may be done to help rule out other conditions or complications include:
- Skin biopsy