Tests and diagnosisBy Mayo Clinic staff
There are no specific tests to confirm Churg-Strauss syndrome, and signs and symptoms are similar to those of other diseases, so it can be difficult to diagnose. To help make diagnosis easier, the American College of Rheumatology has established criteria for identifying Churg-Strauss syndrome.
The six criteria
The disease is generally considered to be present if a person has four of the six criteria, but your doctor may feel confident diagnosing Churg-Strauss even if you meet only two or three of the criteria, which include:
- Asthma. Most people diagnosed with Churg-Strauss syndrome have chronic, often severe asthma.
- Higher than normal count of a type of white blood cells called eosinophils (eosinophilia). Eosinophils normally make up 1 to 3 percent of white blood cells. A count higher than 10 percent is considered abnormally high and a strong indicator of Churg-Strauss syndrome.
- Damage to one or more nerve groups (mononeuropathy or polyneuropathy). Most people with Churg-Strauss syndrome have a type of nerve damage called peripheral neuropathy, which causes numbness or pain in your hands and feet.
- Migratory spots or lesions on a chest X-ray (pulmonary infiltrates). These lesions typically move from one place to another or come and go. On chest X-ray, the lesions mimic pneumonia. Doctors tend to classify this as pulmonary infiltrate with eosinophilia.
- Sinus problems. A history of acute or chronic sinusitis is common in people with Churg-Strauss syndrome.
- White blood cells present outside your blood vessels (extravascular eosinophils). Your doctor may order a tissue biopsy of either your skin or a removed nasal polyp. A biopsy of a person with Churg-Strauss syndrome may show the presence of eosinophils outside of a blood vessel.
To help determine whether you meet any of these criteria, your doctor is likely to request several tests, including:
- Blood tests. When your immune system attacks your body's own cells, as happens in Churg-Strauss syndrome, it forms proteins called autoantibodies. A blood test can detect certain autoantibodies in your blood that can suggest, but not confirm, a diagnosis of Churg-Strauss syndrome. A blood test also can measure the level of eosinophils, although an increased number of these cells may be caused by other diseases, including asthma. Alternately, the number of eosinophils in your blood could be suppressed by steroid medications.
- Imaging tests. X-rays, computerized tomography (CT) scans and magnetic resonance imaging (MRI) look for abnormalities in your lungs and sinuses.
- Biopsy of affected tissue. If other tests suggest Churg-Strauss syndrome, you may have a small sample of tissue (biopsy) removed for examination under a microscope. The doctor may remove tissue from your lungs or another organ, such as skin or muscle, to confirm or rule out the presence of vasculitis. A biopsy is usually performed only on a site that has shown some abnormality on another test.
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