Fibrosis is a medical term that refers to the excessive growth of fibrous, scar-like connective tissue in some part of the body.
Fibrosis can occur in many organs, including the lungs, heart, liver, joints, and skin. Some fibroses have an inherited component. Others develop for no known reason (idiopathic fibrosis). Fibroses in the lung (pulmonary fibroses) often develop from prolonged environmental exposure to dust and chemicals.
Respiratory fibroses are one of the more common and serious types of fibrosis. Pulmonary fibrosis develops when the alveoli, tiny air sacs that transfer oxygen to the blood, become damaged and inflamed. The body tries to heal the damage with scar tissue, but these scars collapse the alveoli and make the lungs less elastic. If the cycle of inflammation and scarring continues, the lungs become increasingly rigid and unable to deliver oxygen to the blood.
Pulmonary fibrosis can result from sarcoidosis, drug reactions, autoimmune diseases, environmental allergies such as Farmer's lung, and exposure to toxic dusts and gases. A number of respiratory fibroses, including such conditions as black lung disease, silicosis, asbestosis, berylliosis, and byssinosis, are linked to specific environmental exposures. Pulmonary fibrosis that develops without a known cause is called idiopathic pulmonary fibrosis. This disease is equally common in men and women. It is usually diagnosed between the ages of 40 and 60.
The first symptom of pulmonary fibrosis usually is shortness of breath, at first, during exercise, but later also while resting. Individuals may also have a dry cough, rapid heartbeat, or enlargement of the fingertips and ends of the toes. Some people feel tired or have a fever, weight loss, muscle or joint pains. In late stages of the disease, the lack of oxygen in the blood can give the skin and mucus membranes a blue tinge known as cyanosis.
Pulmonary fibrosis is often diagnosed and treated by a lung specialist. Several tests usually are needed to diagnose this disease and determine its cause. They include a physical examination, detailed history of the symptoms, chest x rays, lung function tests, and blood tests, including a measurement of the amount of oxygen in the blood. Computed tomography (CT scan) may give a more detailed picture of the lungs. Bronchoscopy may be done to examine the air passages and analyze the cells found deep in the lungs.
Lung biopsies are necessary to diagnose some diseases. Lung biopsies can be done through a needle inserted into the chest through the skin, during bronchoscopy, or as a surgical procedure under general anesthesia.
The treatment of pulmonary fibrosis depends on the underlying cause. Many diseases are treated by suppressing inflammation with corticosteroids. Stronger immune suppressants such as cyclophosphamide (Cytoxan) or azathioprine (Imuran) may also be tried. Some patients need supplemental oxygen. A lung transplant may be an option for incurable diseases. Approximately 60–80% of patients live for at least two years after the transplant.
There is no good treatment for idiopathic pulmonary fibrosis. Only 10–20% of patients with this disease respond to corticosteroids.
Anxiety and fear can make breathing difficulties worse. Some patients find that activities such as yoga, prayer or meditation, music therapy, or biofeedback help to relax them.
Prognosis depends on the specific disease. Some cases may stop progressing or improve, particularly if the cause can be identified and treated. Others may develop quickly or slowly into end-stage lung disease. The course of idiopathic pulmonary fibrosis is very difficult to predict; however, average survival is approximately five to seven years.
There is no known prevention for idiopathic pulmonary fibrosis.
The Occupational Safety and Health Administration sets standards for exposure to particulate matter and toxic chemical gasses in the workplace. The Environmental Protection Agency sets air pollution standards as well.
Some ways to prevent other environmental causes of pulmonary fibrosis are:
See also Air pollution ; Asbestosis ; Berylliosis ; Black lung disease ; Byssinosis ; Cyanosis ; Occupational Safety and Health Administration ; Silicosis .
Tarlo, Susan, Paul Cullinan, and Benoit Nemery, eds. Occupational and Environmental Lung Diseases: Diseases from Work, Home, Outdoor and Other Exposures. Hoboken, NJ: Wiley, 2010.
MedlinePlus “Pulmonary Fibrosis.” http://www.nlm.nih.gov/medlineplus/pulmonaryfibrosis.html (accessed October 30, 2012).
American Lung Association. “Understanding Pulmonary Fibrosis.” http://www.lung.org/lung-disease/pulmonaryfibrosis/understanding-pulmonary.html (accessed October 30, 2012).
American Lung Association, 1301 Pennsylvania Ave. NW, Suite 800, Washington, DC, 20001, (202) 758-3355, Fax: (202) 452-1805, (800) 548-8252, info@lungusa. org, http://www.lungusa.org/ .
Pulmonary Fibrosis Association, 811 W Evergreen Avenue, Suite 303, Chicago, IL, 60642-2642, (888) 733-6741, firstname.lastname@example.org, http://www.pulmonaryfibrosis.org .
Anna Rovid Spickler, DVM, PhD