Certain disorders, drugs, chemicals, fungi, and parasites may cause eosinophils to accumulate in the lungs.
People may cough, wheeze, or feel short of breath, and some people develop respiratory failure.
Doctors use x-rays and laboratory tests to detect the disorder and determine the cause, especially if parasites are suspected as the cause.
Corticosteroids are usually given.
(See also Overview of Interstitial Lung Diseases Overview of Interstitial Lung Diseases Interstitial lung disease (also called diffuse parenchymal disease) is a term used to describe a number of different disorders that affect the interstitial space. The interstitial space consists... read more .)
Eosinophils are a type of white blood cell Eosinophils One of the body's lines of defense (immune system) involves white blood cells (leukocytes) that travel through the bloodstream and into tissues, searching for and attacking microorganisms and... read more that participates in the immune response of the lung. The number of eosinophils increases during many inflammatory and allergic reactions, including asthma Asthma Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli. Coughing, wheezing, and shortness of breath that occur in response to specific triggers are... read more , which frequently accompanies certain types of eosinophilic pneumonia. Eosinophilic pneumonia differs from typical pneumonias Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more in that there is no suggestion that the tiny air sacs of the lungs (alveoli) are infected by bacteria, viruses, or fungi. However, the alveoli and often the airways do fill with eosinophils. Even the blood vessel walls may be invaded by eosinophils, and the narrowed airways may become plugged with an accumulation of secretions (mucus) if asthma develops.
Löffler syndrome, a form of eosinophilic pneumonia, may cause no symptoms or mild respiratory symptoms (most often dry cough). Chest x-rays and blood tests to find elevated levels of eosinophils in the blood are needed for diagnosis. Löffler syndrome is often part of an infestation by any of several species of nematode worms (roundworms), most commonly Ascaris lumbricoides Ascariasis Ascariasis is infection caused by Ascaris lumbricoides, an intestinal roundworm, or occasionally by Ascaris suum (which causes ascariasis in pigs). People acquire the infection by swallowing... read more ; however, a cause may not be identified in as many as one third of people. The disease usually resolves within 1 month. Doctors may give corticosteroids to reduce symptoms and help reduce inflammation.
Causes of Eosinophilic Pneumonia
The exact reason that eosinophils accumulate in the lungs is not well understood, but it may be a type of allergic reaction Overview of Allergic Reactions Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance. Usually, allergies make people sneeze; the eyes water and itch... read more . Often it is not possible to identify the substance that is causing the allergic reaction. However, there are some known causes of eosinophilic pneumonia, including
Certain drugs (for example, penicillin, aminosalicylic acid, carbamazepine, L-tryptophan, naproxen, isoniazid, nitrofurantoin, phenytoin, chlorpropamide, and sulfonamides [such as trimethoprim/sulfamethoxazole])
Chemical fumes (for example, cocaine or nickel inhaled as a vapor)
Fungi (typically Aspergillus fumigatus)
Parasites (particularly roundworms, including nematodes)
Systemic disorders (for example, eosinophilic granulomatosis with polyangiitis Eosinophilic Granulomatosis with Polyangiitis Eosinophilic granulomatosis with polyangiitis is inflammation of small- and medium-sized blood vessels that damages organs and that usually occurs in adults with a history of asthma, nasal allergies... read more )
Symptoms of Eosinophilic Pneumonia
Symptoms may be mild or life threatening, and acute or chronic.
Acute eosinophilic pneumonia progresses quickly. It may cause fever, chest pain worsened by deep breathing, shortness of breath, cough, and a general feeling of illness. The level of oxygen in the blood can decrease severely, and acute eosinophilic pneumonia can progress to acute respiratory failure Respiratory Failure Respiratory failure is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide in the blood becomes dangerously high. Conditions that block... read more in a few hours or days if not treated.
Löffler syndrome may not cause symptoms or may cause only mild respiratory symptoms. A person may cough, wheeze, and feel short of breath but usually recovers quickly.
Chronic eosinophilic pneumonia, which slowly progresses over days or weeks, is a distinct disorder that may also become severe. It tends to remit and recur on its own and may worsen over weeks or months. Life-threatening shortness of breath can develop if the condition is not treated.
Diagnosis of Eosinophilic Pneumonia
Chest x-ray and computed tomography
Blood tests to measure the number of eosinophils
When doctors suspect eosinophilic pneumonia, they first do a chest x-ray.
In acute eosinophilic pneumonia, the chest x-ray is abnormal, but similar abnormalities can occur in other conditions.
In chronic eosinophilic pneumonia, chest x-rays may aid in diagnosis.
Often, computed tomography (CT) of the chest is needed for diagnosis, particularly for acute eosinophilic pneumonia.
The number of eosinophils in the blood are measured. In acute eosinophilic pneumonia, the number of eosinophils in the blood may be normal. In chronic eosinophilic pneumonia, tests show large numbers of eosinophils in the blood, sometimes as many as 10 to 15 times the normal number.
Microscopic examination of cells from washings of the alveoli obtained during bronchoscopy typically shows clumps of eosinophils. Other laboratory tests may be done to search for an infection with fungi or parasites. These tests may include microscopic examination of stool specimens to look for worms and other parasites.
Treatment of Eosinophilic Pneumonia
Eosinophilic pneumonia may be mild, and people with the disease may get better without treatment.
For acute eosinophilic pneumonia, a corticosteroid such as prednisone is usually needed.
In chronic eosinophilic pneumonia, prednisone may be needed for many months or even years.
If a person develops wheezing, the same treatments used for asthma Treatment Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli. Coughing, wheezing, and shortness of breath that occur in response to specific triggers are... read more are given as well. If worms or other parasites are the cause, the person is treated with appropriate drugs. Ordinarily, drugs that may be causing the illness are stopped.