Pleurisy means inflammation of the pleura, the membrane that covers the lungs and lines the inside of the chest cavity. Depending on its cause, pleurisy can be associated with an accumulation of fluid in the space between the lungs and chest wall called a pleural effusion, or it can be dry pleurisy, which has no fluid accumulation.
Pleurisy can develop many ways, including:
Lung infection — In industrialized nations, bacterial pneumonia (lung infection) resulting from staphylococci, pneumococci, Haemophilus influenzae or other organisms is a frequent cause of pleurisy. In developing nations where tuberculosis is common, pulmonary tuberculosis is another important cause. When pleurisy is caused by a bacterial lung infection, it can be associated with a pus-filled pleural effusion. Viral lung infections, especially epidemic pleurodynia (an infection usually caused by coxsackieviruses or echoviruses), also can cause pleurisy.
Pulmonary embolism — A pulmonary embolism is a blood clot that has floated through the bloodstream and lodged in the lungs. In people with pulmonary embolism, symptoms of pleurisy tend to occur when the pulmonary embolism is fairly small and has lodged in a part of the lungs near the pleura.
Lung cancer — Pleurisy can develop in people with lung cancer. When pleurisy occurs because of lung cancer, a bloody pleural effusion is common.
Rheumatic fever — Rheumatic fever, an inflammatory condition that sometimes occurs after a streptococcal infection, can cause pleurisy, as well as inflammation in other parts of the body, including the heart and joints.
Connective tissue disorders — Systemic lupus erythematosus (SLE or lupus) and other connective tissue disorders can cause inflammation of the pleura.
Rare causes — Radiation therapy (for cancer), a collapsed lung (pneumothorax) and pericarditis (as with severe kidney failure or following a heart attack) all can be associated with pleurisy.
No identifiable cause — Pleurisy can develop for no clear reason despite extensive investigation. These cases are rare, and usually are presumed to be caused by a viral infection.