NORD gratefully acknowledges Nausherwan K. Burki, MD, PhD, University of Connecticut Health Center, for assistance in the preparation of this report.
Chronic eosinophilic pneumonia (CEP) is a rare disorder characterized by the massive accumulation of eosinophils in the lungs (pulmonary eosinophilia). Eosinophils are a type of white blood cell and are part of the immune system. They are usually produced in response to allergens, inflammation or infection (especially parasitic ones) and are particularly active in the respiratory tract. In CEP, eosinophils also accumulate in the bloodstream (peripheral eosinophilia). Common symptoms include shortness of breath (dyspnea), cough, fatigue, night sweats, low grade fevers, and unintended weight loss. The exact cause of CEP is unknown (idiopathic).Introduction
CEP was first described as a distinct entity in the medical literature by Carrington, et al. in 1969 when they described nine individuals with the disorder. It is classified as a form of eosinophilic lung disease, a large group of interstitial lung diseases. CEP is different from acute eosinophilic pneumonia (AEP), which is marked by rapid onset, the absence of asthma, a greater potential for acute respiratory failure and no relapse following treatment. For more information on AEP, choose "acute eosinophilic pneumonia" as your search term in the Rare Disease Database.
Symptoms of CEP are general and nonspecific. The disorder is chronic and slowly progressive with symptoms usually developing insidiously over weeks or months. Breathing (respiratory) difficulties are always present in some form and can include progressive shortness of breath (dyspnea) and a nonproductive cough. Dyspnea can range from mild to severe. Wheezing occurs in approximately 50% of individuals. Some individuals may cough up a mixture of saliva and mucus (sputum).
Additional symptoms associated with CEP include abnormal weakness or lack of energy (asthenia), night sweats, low grade fevers, and unintended (and sometimes marked) weight loss. Less frequently, a general feeling of poor health (malaise), chills, and chest pain may occur.
Some individuals with CEP have pre-existing asthma or a history of allergies. The exact percentage of individuals with pre-existing asthma is unknown and estimates in the medical literature vary greatly, ranging anywhere from one-third to two-thirds of affected individuals. Airway obstruction associated with such conditions tends to worsen in individuals with CEP. In some cases, individuals with no history of asthma or allergies developed the conditions after developing CEP. Asthma associated with CEP is often severe. Approximately 75% of individuals with CEP experience asthma at some point during their lives.
Additional non-respiratory symptoms in individuals with CEP are uncommon. However, joint pain, nerve damage and general skin or gastrointestinal symptoms have been reported in the medical literature.
CEP tends to recur and many individuals will relapse at some point, especially when therapy is not maintained. A relapse can occur as much as 10 years or more after the initial episode. Some individuals eventually develop severe asthma. In some cases, individuals with CEP have developed a related disorder known as Churg-Strauss syndrome, suggesting that there may be an overlap between these two disorders. For more information on Churg-Strauss syndrome see the Related Disorders section below.
CEP is caused by the abnormal accumulation of eosinophils in lung tissue and the bloodstream. Normally, eosinophils only account for approximately 5% of circulating white blood cells in healthy individuals. Researchers believe that CEP may develop due to an unidentified, nonspecific triggering agent that causes the body to produce eosinophils. The exact reason for the overproduction and accumulation of eosinophils is unknown.
Some researchers believe that cytokines (specialized proteins secreted from certain immune system cells that either stimulate or inhibit the function of other immune system cells) may play a role in the development of eosinophilic disorders. Interleukin-5 (IL-5) is a cytokine that is known to be a regulator of the development and function of eosinophils. It is possible that IL-5 might suppress the normal disintegration (apoptosis) of eosinophils resulting the in their accumulation within the lungs and bloodstream. More research is necessary to determine the exact role, if any, of IL-5 in the development of eosinophilic disorders such as CEP.
While CEP often occurs as an isolated finding, it sometimes occurs along with an additional disorder such as polyarteritis nodosa, rheumatoid arthritis, scleroderma, ulcerative colitis or forms of lymphoma or carcinoma. The exact relationship between these disorders and the development of CEP in such cases is unknown.
CEP is a rare disorder, but the exact prevalence is unknown. The disorder can occur in individuals of any age, but is extremely rare in childhood. The peak incidence is during the fifth decade. CEP occurs twice as often in women than men.
A diagnosis of CEP is based upon identification of characteristic symptoms (e.g., eosinophilic pneumonia), a detailed patient history, a thorough clinical evaluation, the absence of other known causes of eosinophilic lung disease, and a variety of specialized tests. A physical examination may reveal low levels of oxygen in the blood (hypoxemia), a rapid heart rate (tachycardia), wheezes and a rattling sound in the lungs (rales).
Clinical Testing and Work-Up
Imaging techniques may be used to help confirm a diagnosis of CEP including chest x-ray or computerized tomography (CT) scanning. Chest x-rays in individuals generally show white patches (infiltrates) in the outer zones of the lungs. A CT scan may reveal hazy areas (ground-glass opacities) that are not seen on traditional x-rays. During CT scanning, a computer and x-rays are used to create a film showing cross-sectional images of certain tissue structures.
An exam known as bronchoalveolar lavage (BAL) may be used to help obtain a diagnosis of CEP. During BAL, a narrow tube (bronchoscope) is slid down the windpipe into the lungs and a sterile solution is passed through the tube washing out (lavaging) cells. This fluid is collected and then the tube in removed, allowing the cells to be studied. BAL in individuals with CEP reveals abnormally high levels of eosinophils.
Blood tests may reveal elevated levels of eosinophils and/or serum immunoglobulin E (IgE). Pulmonary function tests are normal in mild cases, but in more severe cases can show a restricted or obstructed pattern. Additional tests may be performed to rule out other conditions or other causes of pulmonary eosinophilia.
Individuals with CEP respond rapidly and often dramatically to oral corticosteroid therapy such as prednisone. There is no agreed upon initial dose recommended in the medical literature. Significant improvement is often seen within one to two weeks, but can occur within 48 hours. Relapse of CEP is common, especially if corticosteroid therapy is stopped within the first 6 months of treatment. In some cases, simply lowering the dose (tapering) can cause a relapse. Relapses have been reported as late as 10 years after initial therapy. Many individuals need long-term corticosteroid therapy, which can potentially be associated with side-effects. In approximately 10% of cases symptoms go away without treatment (spontaneous remission).
There are anecdotal reports in the medical literature of physicians using inhaled corticosteroids (along with standard oral corticosteroid therapy) in an attempt to reduce the maintenance dose of corticosteroid therapy without increasing the risk of relapse. Whether inhaled corticosteroid therapy can lead to a reduction in the maintenance dose of corticosteroids or reduce the rate of relapse is controversial. More research is necessary to determine the long-term safety and effectiveness of inhaled corticosteroids as a combination therapy for individuals with CEP.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, in the main, contact:
Chronic Eosinophilic Pneumonia Resources
Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder.
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