Pleural fibrosis is a condition in which the pleura, the tissue which covers the lungs, develops fibrous tissue. Under normal conditions, the pleura is a very flexible mucus membrane, but when pleural fibrosis occurs, the pleura thickens and stiffens. The fibrous growth is benign, but it can cause complications for the patient if it is widespread, and it may be associated with a disease process which could be harmful for the patient.
There are a number of causes for pleural fibrosis. It is often linked with asbestos exposure, and dissection of the pleura by a pathologist in severe cases often shows asbestos fibers embedded in the pleura, sometimes as long as 15 years after exposure. It can also be caused by inflammatory processes, surgical trauma, or pleural effusion. In mild cases, the condition causes the development of small areas of fibrous tissue which may cause no problems for the patient, and are classically identified on chest x-rays taken for unrelated reasons.
In severe cases, the entire pleura can thicken, becoming very dense and white, almost like the pith of an orange, causing it to lose the elastic properties which normally allow the tissue to easily expand when the lungs are inflated. As the pleura thickens, the lungs have to work harder to inflate, and eventually the thickened tissue can impair lung function to the point where a patient cannot breathe or has extreme difficulty breathing. In these situations, the damaged pleura must be removed surgically so that the lungs will be able to inflate.
Patients with the severe form tend to seek medical attention as they develop difficulty breathing. A doctor can diagnose the condition with tools such as a chest x-ray, a biopsy of the suspicious tissue, and listening to the lungs. Biopsies are often recommended even in mild cases to confirm that the growth is benign, rather than cancerous, as the treatment for cancer is quite different from the approach to pleural fibrosis.
It is also possible to see pleural calcification associated with pleural fibrosis. In pleural calcification, small white plaques appear on the pleural membrane. In mild cases, these plaques may not be problematic, but they can become a cause for concern if they grow large, spread, or associated with widespread pleural fibrosis. Fibrosis can also occur in the mucus membranes which surround other areas of the viscera, such as the heart and intestines.