(See also Overview of Idiopathic Interstitial Pneumonias Overview of Idiopathic Interstitial Pneumonias 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... read more .)
Most people who have nonspecific interstitial pneumonia are women between the ages of 40 and 50. Most have no known cause or risk factor. However, a similar process can develop in people with connective tissue disorders (in particular, systemic sclerosis Systemic Sclerosis Systemic sclerosis is a rare, chronic autoimmune rheumatic disorder characterized by degenerative changes and scarring in the skin, joints, and internal organs and by blood vessel abnormalities... read more , polymyositis Autoimmune Myositis Autoimmune myositis causes inflammation and weakness in the muscles (polymyositis) or in the skin and muscles (dermatomyositis). Muscle damage may cause muscle pain and muscle weakness may cause... read more , or dermatomyositis Autoimmune Myositis Autoimmune myositis causes inflammation and weakness in the muscles (polymyositis) or in the skin and muscles (dermatomyositis). Muscle damage may cause muscle pain and muscle weakness may cause... read more ), in some forms of drug-induced lung injury Drug-Induced Pulmonary Disease Drug-induced pulmonary disease is not a single disorder. Many drugs can cause lung problems in people who have no other lung disorders. The type of problem depends on the drug involved, but... read more , and in people with hypersensitivity pneumonitis Hypersensitivity Pneumonitis Hypersensitivity pneumonitis is a type of inflammation in and around the tiny air sacs (alveoli) and smallest airways (bronchioles) of the lung caused by a hypersensitivity reaction to inhaled... read more .
A dry cough and shortness of breath develop over months to years. Low-grade fever and a feeling of illness (malaise) may occur, but high fever, weight loss, and other general symptoms of illness are unusual.
As with other idiopathic interstitial pneumonias, chest x-rays and computed tomography (CT) are done. Pulmonary function testing Pulmonary Function Testing (PFT) Pulmonary function tests measure the lungs' capacity to hold air, to move air in and out, and to absorb oxygen. Pulmonary function tests are better at detecting the general type and severity... read more usually shows that the amount of air the lungs can hold is below normal. The amount of oxygen in the blood is often low at rest and is even lower during exercise.
Doctors sometimes do bronchoscopy Bronchoscopy Bronchoscopy is a direct visual examination of the voice box (larynx) and airways through a viewing tube (a bronchoscope). A bronchoscope has a camera at the end that allows a doctor to look... read more and wash segments of the lung with a salt-water solution and then collect the washings (bronchoalveolar lavage) for testing. More than half of people have more lymphocytes (a type of white blood cell) than normal in the washings.
Lung biopsy is often needed to confirm the diagnosis.
Corticosteroids sometimes together with immunosuppressants are usually effective. Survival depends on how severe the disease is. People with mild disease often survive for at least 10 years after being diagnosed. However, survival declines to 3 to 5 years in people with more severe disease.