Interstitial Lung Disease / Pulmonary Fibrosis

Interstitial lung disease is a general category that includes many different lungconditions. All interstitial lung diseases affect the interstitium, a part of the lungs' anatomic structure. The interstitium is a lace-like network of tissue that extends throughout both lungs. The interstitium provides support to the lungs' microscopic air sacs (alveoli). Tiny blood vessels travel through the interstitium, allowing gas exchange between blood and the air in the lungs. Normally, the interstitium is so thin it can't be seen on chest X-rays or CT scans.

Types of Interstitial Lung Disease

All forms of interstitial lung disease cause thickening of the interstitium. The thickening can be due to inflammation, scarring, or extra fluid (edema). Some forms of interstitial lung disease are short-lived; others are chronic and irreversible.

Some of the types of interstitial lung disease include:

Interstitial pneumonia: Bacteria, viruses, or fungi may infect the interstitium of the lung. A bacterium called Mycoplasma pneumonia is the most common cause. Idiopathic pulmonary fibrosis : A chronic, progressive form of fibrosis (scarring) of the interstitium. Its cause is unknown.

Causes of Interstitial Lung Disease

Bacteria, viruses, and fungi are known to cause interstitial pneumonias. Regular exposures to inhaled irritants at work or during hobbies can also cause some interstitial lung disease.

These irritants include:
  • Asbestos
  • Silica dust
  • Talc
  • Coal dust, or various other metal dusts from working in mining
  • Grain dust from farming
  • Bird proteins (such as from exotic birds, chickens, or pigeons) Definition

Interstitial Pulmonary Fibrosis is the scarring and thickening of the lung tissues, a form of interstitial lung disease.


Interstitial lung disease refers to a group of diseases that are chronic, nonmalignant, and noninfectious. These diseases are characterized by infiltration of inflammatory cells into the walls of the alveoli (the air sacs of the lungs). The infiltration causes abnormal scarring in the connective tissue that supports the alveoli. If the disease progresses, scarring develops to the point that the lungs may be destroyed. The causes of most interstitial lung disorders are unknown. These ailments generally affect people over 50 years of age. Idiopathic pulmonary fibrosis is the most common diagnosis among patients presenting with interstitial lung disease. It is a chronic, noninfectious, nonmalignant disorder that causes progressive shortness of breath. Average duration of life after the onset of symptoms is 4 to 5 years, but many affected persons live much longer. Males and females are affected equally. The disorder commonly develops in the middle years of life but it can occur at any age.


The cause of idiopathic pulmonary fibrosis is unknown. Inhalation of certain toxins, autoimmune disease, and radiation may cause pulmonary fibrosis. Medications including bleomycin, busulfan, phenytoin, and nitrofurantoin may cause interstitial fibrosis.


  • A major consequence of the formation of abnormal scar tissue is impairment of the transfer of oxygen from the air to the blood. Thus, an affected person may notice fatigue, malaise, and shortness of breath, particularly in connection with exercise. Occasionally, a cough that produces no sputum, and a sensation of chest discomfort are also present.
  • Lung cancer is a type of cancer that begins in the lungs. Your lungs are two spongy organs in your chest that take in oxygen when you inhale and release carbon dioxide when you exhale. Lung cancer is the leading cause of cancer deaths in the United States, among both men and women. Lung cancer claims more lives each year than do colon, prostate, ovarian and breast cancers combined. People who smoke have the greatest risk of lung cancer. The risk of lung cancer increases with the length of time and number of cigarettes you've smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer. One fourth of all people with lung cancer have no symptoms when the cancer is diagnosed. These cancers are usually identified incidentally when a chest X-ray is performed for another reason. The other three-fourths of people develop some symptoms. The symptoms are due to direct effects of the primary tumor; to effects of cancer spread to other parts of the body (metastases); or to disturbances of hormones, blood, or other systems.

Symptoms of lung cancer include cough, coughing up blood or rusty-colored phlegm, fatigue, unexplained weight loss, recurrent respiratory infections, hoarseness, new wheezing, and shortness of breath.

  • A new cough in a smoker or a former smoker should raise concern for lung cancer.
  • A cough that does not go away or gets worse over time should be evaluated by a health care provider.
  • Coughing up blood (hemoptysis) occurs in a significant number of people who have lung cancer. Any amount of coughed-up blood should be evaluated by a health care provider.
  • Pain in the chest area is a symptom in about one fourth of people with lung cancer. The pain is dull, aching, and persistent.,/li>
  • Shortness of breath usually results from a blockage in part of the lung, collection of fluid around the lung (pleural effusion), or the spread of tumor through the lungs.
  • Wheezing or hoarseness may signal blockage or inflammation in the lungs that may go along with cancer.
  • Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.