Idiopathic interstitial pneumonias are interstitial lung diseases that have no known cause that have some similarities in symptoms and how they affect the lungs.
Some types of these diseases are much more serious than others.
Diagnosis requires chest x-rays, computed tomography, and occasionally analysis of a sample of lung tissue (biopsy).
Treatment depends on the disease type.
(See also Overview of Interstitial Lung Diseases.)
The word idiopathic means of unknown cause, so when the cause of interstitial lung disease is not identified, idiopathic interstitial pneumonia is diagnosed. Pneumonias are often thought of as infections, but these diseases do not appear to result from infection.
There are eight types of idiopathic interstitial pneumonias. In decreasing order of frequency, they are
All types cause cough and shortness of breath and affect the lungs similarly. The ends of the fingers may become thick or club-shaped (see figure Recognizing Finger Clubbing). Through a stethoscope, doctors often hear crackling sounds. Although symptoms may be similar, disorders differ in how quickly symptoms develop, how they are treated, and how serious they are.
Comparing Types of Idiopathic Interstitial Pneumonias*
Disorder | People Most Often Affected | Percentage of Affected People Who Smoke Cigarettes | Treatment | Outlook |
|---|---|---|---|---|
Idiopathic pulmonary fibrosis | More frequently, men over 50 | More than 60% | Pulmonary rehabilitation Lung transplantation | 50–70% die in 5 years. |
Desquamative interstitial pneumonia | More frequently, men aged 30–50 | More than 90% | Smoking cessation Corticosteroids | 70% survival at 10 years. |
Nonspecific interstitial pneumonia | More frequently, women aged 40–60 | Fewer than 40% | Corticosteroids | Fewer than 50% die in 5 years. Mortality rate: widely variable, but generally better than idiopathic pulmonary fibrosis. |
Cryptogenic organizing pneumonia | People of any age, usually aged 40–50 | Fewer than 50% | Corticosteroids | Relapses are common 5-year survival rate is > 90% Death is rare. |
Respiratory bronchiolitis–associated interstitial lung disease | People aged 30–50 (slightly more men) | More than 90% | Smoking cessation Corticosteroids | Death is rare as long as people stop smoking. |
Acute interstitial pneumonia | People of any age | Unknown | Best treatment unknown Sometimes corticosteroids | More than 50% die in less than 6 months. |
Lymphoid interstitial pneumonia | Mostly women of any age | Unknown | Corticosteroids | The prognosis is difficult to predict, |
Idiopathic pleuroparenchymal fibroelastosis | People of any age (median age 57) | Usually non-smokers | Best treatment unknown (possibly corticosteroids) | 5-year survival rate is approximately 25 to 60%. |
* In decreasing order of frequency. | ||||
Diagnosis of Idiopathic Interstitial Pneumonias
Chest computed tomography
Computed tomography (CT) of the chest is the main imaging tool used in the evaluation of idiopathic interstitial pneumonias. CT may allow doctors to make a diagnosis. If not, doctors remove a small sample of lung tissue for examination under a microscope (lung biopsy). Usually, biopsy is done surgically with use of a thoracoscope.
Blood tests are usually done. They usually cannot confirm the diagnosis but are done as part of the search for other disorders. Doctors may also do electrocardiography (ECG) or echocardiography to determine whether the heart has been affected by the lung disease.
Treatment of Idiopathic Interstitial Pneumonias
Smoking cessation
Often drugs, corticosteroids or novel antifibrotic drugs, depending on the disease
Sometimes lung transplantation
Smoking cessation is always recommended because smoking is likely to make the disorder progress more rapidly.
Other treatments depend on the type of idiopathic interstitial pneumonia but may include corticosteroids or other drugs, such as novel antifibrotic drugs.
In some people, lung transplantation is done.
