What is eosinophilic granulomatosis with polyangiitis (Churg-Strauss)?
Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Churg-Strauss, is an extremely rare disease – there are only two to five new cases a year per one million people. EGPA is caused by inflammation (swelling) that occurs in certain types of cells in blood or in tissues. This inflammation causes injury to organ systems – the most commonly involved are the lungs, nose, sinuses, skin, joints, nerves, intestinal tract, heart, and kidneys. A main feature of EGPA is that all patients have a history of asthma and/or allergies.
Almost all people with EGPA have increased numbers of "allergic type" blood cells called eosinophils. Eosinophils are a type of white blood cell that usually make up 5% or less of the total white blood cell count. In EGPA, eosinophils usually make up more than 10% of the total white blood cell count. In addition, most biopsies (tissue samples) contain clusters of cells called "granulomas" that may or may not involve blood vessels. The granulomas often include eosinophils and are therefore called "allergic granulomas." In fact, another name for EGPA is allergic granulomatosis. Some of the most serious cases of EGPA are related to vasculitis.
What is vasculitis?
Vasculitis is a general medical term that means inflammation of the blood vessels. When blood vessels become inflamed, several things can happen:
They can grow weak and stretch in size, which can cause an aneurysm to develop. (An aneurysm is an abnormal blood-filled enlargement of a blood vessel.)
The walls can become thinner. If they do, the walls can rupture, and blood leaks out into tissue.
They can narrow to the point of closing. This can cause damage to the organs from the loss of oxygen and nutrients that were being supplied by the blood.
What are the symptoms of EGPA?
Because EGPA can affect several different organ systems, there is a wide range of symptoms.
Patients who have EGPA may feel generally ill and fatigued or have fevers. They may lose their appetite, and lose weight. Other symptoms depend on the organs or diseases involved. For example, patients may have:
Shortness of breath from asthma or inflammation in the air sacs and blood vessels of the lung
Chest pain from disease that affects the lungs or heart
Rashes on the skin
Muscle and/or joint pain
Increased nasal discharge (runny nose) or facial pain from sinusitis
Abdominal pain or blood in the stools from intestinal tract involvement
Abnormal feelings, and numbness or loss of strength and feeling from nerve involvement
The patient may have any combination of these symptoms.
Kidney disease caused by EGPA often does not have any symptoms. The patient may not know about inflammation of the kidney until the kidneys begin to stop working. Therefore, patients with any form of vasculitis must have regular urinalyses (examinations of the urine).
What causes EGPA?
The cause of EGPA is unknown. EGPA is not a form of cancer, it is not contagious, and it does not usually run in families.
The immune system plays a role in EGPA. The immune system acts to protect the body against “foreign invaders” (germs, bacteria) that cause infections, disease, and other injuries to the body. Sometimes the immune system does not protect the body as it should.
Who is affected by EGPA?
EGPA can occur in people of all ages, from children to the elderly. The average age that someone is diagnosed is between 35 and 50 years old. EGPA appears to affect men and women equally.
How is EGPA diagnosed?
The doctor may use the following tests to diagnose EGPA:
Medical history: to look for EGPA symptoms, especially asthma, allergies, and other features of the disease.
Physical examination: to discover which organs are involved and to rule out other illnesses that may look similar.
Blood tests: to look for abnormal blood counts and an increase in eosinophils.
Urinalysis: to detect whether there is too much protein, or red blood cells, in the urine.
Imaging tests such as x-rays and computed tomography (CT) to look for any abnormalities in areas such as the lungs or sinuses.
Once the diagnosis of EGPA is suspected, a biopsy (tissue sample) is often performed to try to find eosinophils, eosinophilic granulomas, and/or vasculitis. Biopsies are not required in all cases, and are only recommended when abnormal findings are seen in the exam, laboratory tests, or imaging tests.
How is EGPA treated?
A variety of immunosuppressive drugs (drugs that suppress the immune system) are used to treat EGPA. The doctor will choose the drug based on how the EGPA is affecting the patient--whether it is mild (for instance, affecting the skin or joint), or potentially life-threatening.
Corticosteroids such as prednisone or prednisolone are the most commonly used treatments. People who have a mild disease (those whose disease does NOT affect the nervous system, heart, kidneys, intestinal tract, or show other features of severe disease) might do extremely well on corticosteroid therapy alone. Once the patient has a dramatic improvement on this drug, the dosage is reduced to the lowest amount that keeps the disease under control.
People with EGPA that affects critical organs are usually treated with corticosteroids combined with another immunosuppressive drug, such as cyclophosphamide (Cytoxan®), methotrexate, or azathioprine (Imuran®).
These drugs are also used to treat other medical conditions. Azathioprine is used to prevent organ transplant rejection and is also a treatment for rheumatoid arthritis and lupus. High doses of cyclophosphamide and methotrexate are used to treat certain types of cancer. In vasculitis, these drugs are given at doses that are 10 to 100 times lower than that used to treat cancer in order to suppress the immune system.
All immunosuppressive drugs can have side effects. Each drug can have its own side effects, so it is very important to watch for them. A person with EGPA may tolerate these drugs at first; however, this may not last. This is why it’s so important to watch for side effects, even after the patient stops taking the drug. Blood tests are also used to evaluate the illness itself.
The goal of treatment is to stop all damage that comes from EGPA; this is known as "remission." Once the disease begins to improve, the doctor slowly reduces the corticosteroid dose, and eventually hopes to stop it completely. Stopping it completely may be difficult if a person has significant asthma, as the airways can be very sensitive to corticosteroids.
If cyclophosphamide is used for severe EGPA, it is often only given until the patient goes into remission (usually around 3 to 6 months); the patient is then switched to another immunosuppressive agent, such as methotrexate or azathioprine, to maintain remission.
The duration of maintenance immunosuppressive drug depends on the patient. In most instances, it is given for least one to two years before the doctor considers slowly reducing the dosage and eventually stopping it.
What is the outlook for patients with EGPA?
Although EGPA can be an increasingly serious illness, many patients do extremely well. On average, after five years of illness, more than 80% of patients survive the effects of EGPA. How patients with EGPA do is strongly related to how severe their illness is.
The best opportunity to limit damage to the organs is when treatment starts right away and is carefully supervised by a doctor who is knowledgeable about EGPA. Even patients who have the most severe EGPA can go into remission when they are treated quickly and followed closely.
After a patient goes into remission, it is possible that the EGPA can come back ("relapse"). People with asthma or nasal allergies can often have worsening of these symptoms that is separate from vasculitis.
Relapses involving vasculitis occur in about 30% to 50% of people with EGPA. These relapses may be similar to what the person experienced at the time of their vasculitis diagnosis.
It’s possible to reduce the likelihood of a severe relapse by reporting any new symptoms to the doctor right away, seeing the doctor on a regular basis, and having regular checkups with laboratory tests and imaging. The treatment approach for relapses is similar to that of newly diagnosed disease, and it’s possible again for these patients to go into remission again.
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