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Hypersensitivity pneumonitis
Extrinsic allergic alveolitis; Farmer's lung; Mushroom picker's disease; Humidifier or air-conditioner lung; Bird breeder's or bird fancier's lung
Hypersensitivity pneumonitis is inflammation of the lungs due to breathing in a foreign substance, usually certain types of dust, fungus, or molds.
Causes
Hypersensitivity pneumonitis usually occurs in people who work in places where there are high levels of organic dusts, fungus, or molds.
Long-term exposure can lead to lung inflammation and acute lung disease . Over time, the acute condition turns into long-lasting (chronic) lung disease.
Lung disease
Lung disease is any problem in the lungs that prevents the lungs from working properly. There are three main types of lung disease:Airway diseases -...
Hypersensitivity pneumonitis may also be caused by fungi or bacteria in humidifiers, heating systems, and air conditioners found in homes and offices. Exposure to certain chemicals, such as isocyanates or acid anhydrides, can also lead to hypersensitivity pneumonitis.
Examples of hypersensitivity pneumonitis include:
Bird fancier's lung: This is the most common type of hypersensitivity pneumonitis. It is caused by repeated or intense exposure to proteins found in the feathers or droppings of many species of birds.
Farmer's lung: This type of hypersensitivity pneumonitis is caused by exposure to dust from moldy hay, straw, and grain.
Symptoms
Symptoms of acute hypersensitivity pneumonitis often occur 4 to 6 hours after you have left the area where the offending substance is found. This makes it difficult to find a connection between your activity and the disease. Symptoms might resolve before you go back to the area where you encountered the substance.
Symptoms may include:
- Chills
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Cough
Cough
Coughing is an important way to keep your throat and airways clear. But too much coughing may mean you have a disease or disorder. Some coughs are d...
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Fever
Fever
Fever is the temporary increase in the body's temperature in response to a disease or illness. A child has a fever when the temperature is at or abov...
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Malaise
(feeling ill)
Malaise
Fatigue is a feeling of weariness, tiredness, or lack of energy.
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Shortness of breath
Shortness of breath
Breathing difficulty may involve:Difficult breathingUncomfortable breathingFeeling like you are not getting enough air
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Symptoms of chronic hypersensitivity pneumonitis may include:
- Breathlessness, especially with activity
- Cough, often dry
- Loss of appetite
- Unintentional weight loss
Exams and Tests
Your dosctor may hear abnormal lung sounds called crackles (rales) when listening to your chest with a stethoscope.
Lung changes due to chronic hypersensitivity pneumonitis may be seen on a chest x-ray . Other tests may include:
Chest x-ray
A chest x-ray is an x-ray of the chest, lungs, heart, large arteries, ribs, and diaphragm.
- Aspergillus precipitin test
-
Bronchoscopy
with washings, biopsy, and bronchoalveolar lavage
Bronchoscopy
Bronchoscopy is a test to view the airways and diagnose lung disease. It may also be used during the treatment of some lung conditions.
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Complete blood count (
CBC
)
CBC
A complete blood count (CBC) test measures the following:The number of red blood cells (RBC count)The number of white blood cells (WBC count)The tota...
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High-resolution
CT scan of the chest
CT scan of the chest
A chest CT (computed tomography) scan is an imaging method that uses x-rays to create cross-sectional pictures of the chest and upper abdomen....
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Hypersensitivity pneumonitis
antibody
panels
Antibody
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
ImageRead Article Now Book Mark Article - Krebs von den Lungen-6 assay (KL-6)
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Pulmonary function tests
Pulmonary function tests
Pulmonary function tests are a group of tests that measure breathing and how well the lungs are functioning.
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Surgical lung biopsy
Surgical lung biopsy
An open lung biopsy is surgery to remove a small piece of tissue from the lung. The sample is then examined for cancer, infection, or lung disease....
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Treatment
First, the offending substance must be identified. Treatment involves avoiding this substance in the future. Some people may need to change jobs if they cannot avoid the substance at work.
If you have a chronic form of this disease, your doctor may recommend that you take glucocorticoids (anti-inflammatory medicines). Sometimes treatments used for asthma can help people with hypersensitivity pneumonitis.
Outlook (Prognosis)
Most symptoms go away when you avoid or limit your exposure to the material that caused the problem.
Possible Complications
The chronic form of this disease may lead to pulmonary fibrosis . This is a scarring of the lung tissue that often is not reversible. Eventually, end-stage lung disease and respiratory failure can occur.
Pulmonary fibrosis
Interstitial lung disease is a group of lung disorders in which the lung tissues become inflamed and then damaged.
When to Contact a Medical Professional
Call your health care provider if you develop symptoms of hypersensitivity pneumonitis.
Prevention
The chronic form can be prevented by avoiding the material that causes the lung inflammation.
References
Douglass JA, Sandrini A, Holgate ST, O'Hehir RE. Allergic bronchopulmonary aspergillosis and hypersensitivity pneumonitis. In: Adkinson NF, Bochner BS, Burks W, et al, eds. Middleton's Allergy: Principles and Practice . 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 61.
Patterson KC, Rose CS. Hypersensitivity pneumonitis. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine . 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 64.
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Bronchoscopy - illustration
Bronchoscopy is a surgical technique for viewing the interior of the airways. Using sophisticated flexible fiber optic instruments, surgeons are able to explore the trachea, main stem bronchi, and some of the small bronchi. In children, this procedure may be used to remove foreign objects that have been inhaled. In adults, the procedure is most often used to take samples of (biopsy) suspicious lesions and for culturing specific areas in the lung.
Bronchoscopy
illustration
-
Respiratory system - illustration
Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs.
Respiratory system
illustration
-
Bronchoscopy - illustration
Bronchoscopy is a surgical technique for viewing the interior of the airways. Using sophisticated flexible fiber optic instruments, surgeons are able to explore the trachea, main stem bronchi, and some of the small bronchi. In children, this procedure may be used to remove foreign objects that have been inhaled. In adults, the procedure is most often used to take samples of (biopsy) suspicious lesions and for culturing specific areas in the lung.
Bronchoscopy
illustration
-
Respiratory system - illustration
Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs.
Respiratory system
illustration
Review Date: 6/22/2015
Reviewed By: Denis Hadjiliadis, MD, MHS, Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
