What is a pleural effusion?
A pleural effusion is a build up of fluid between a lung and the chest wall. The lungs are covered by lining’s which are called the pleura. The pleura have an inner and outer layer. The inner layer covers the lungs. The outer layer lines the rib cage and diaphragm which is a sheet of muscle that seperates the chest from the abdomen.
The pleura produces fluid which acts as a lubricant between the chest wall and lungs as they move during breathing. A pleural effusion therefore occurs when too much fluid builds up between the two layers of the pleura.
Pleural effusions are quite common and are often due to infections such as pneumonia or heart failure, which is when the heart is not pumping the blood efficently around the body. Heart failure causes pressure in the veins that take the blood back to the heart. Some fluid may seep out of the blood vessels. Swelling of the legs with fluid is typical with heart failure but a pleural effusion may also develop.
Some arthritis conditions can cause a pleural effusion and for examaple rheumatoid arthritis is a common cause of pleural effusion. Some arthitic conditions may also cause inflammation of the pleura in addition to joint inflamation. Systemic lupus erythematosis is a known cause.
A low level of protein in the blood also tends to allow fluid to seep out of the blood vessels. For example cirrhosis of the liver and some kidney diseases may cause a low level of blood protein which allows a pleural effusion to develop.
However, a pleural effusion can also be a sign of something more sinister and may be a symptom of several different type of cancer. Almost any type of cancer can cause a pleural effusion if it spreads to the chest area although the most common are those below.
- Lung cancer
- Breast cancer
- Ovarian cancer
Pleural effusions are often a very common sign of mesothelioma but also other asbestos conditions such as asbestos related lung cancer.