Causes of Pleural Diseases
There are hundreds of causes for the development of pleural diseases. The most common of them are
- Infection: Viral infection is the most common cause of pleurisy, but bacterial, fungal and parasitic infections also cause parapneumonic effusions/empyema. In India, the Early stage of Tuberculosis is one of the most common causes of pleural infection. Typically, this is due to a small area of pneumonia spreading to cover the pleura, leading to infected fluid formation.
- Pneumothorax: Air accumulation follows blunt or penetrating lung injury after accidents but can occur along with advanced lung disease of any cause. Primary spontaneous pneumothorax is a disease that occurs in smokers due to undiagnosed weakness in their lungs and their covering.
- Hemothorax: Blood accumulation follows blunt or penetrating lung injury but can follow surgery, invasive hospital procedures and rarely, blood thinners.
- Pleural effusion associated with systemic disease: is most often the result of congestive heart failure but also occurs in advanced liver disease, kidney disease, thyroid disorders and low proteins.
- Pleural diseases due to specific lung disease: In these, sometimes the lung disease is not prominent and symptoms are due to effusion/inflammation. Some of the common causes are:
- Auto-immune diseases: like rheumatoid arthritis can involve the pleural covering, leading to air or fluid accumulation.
- Cancers: Lung cancers and cancers in other organs (commonly breast, blood cancers, and colorectal cancers) can spread to the pleural covering with minimal lung disease. Primary cancers of the pleura called mesothelioma are rare but are specifically linked to asbestos exposure (insulation, shipyard construction/breaking, etc.).
- Blood clots in the lungs (pulmonary embolism).
- Drug exposure: certain drugs can cause damage to the pleura, leading to fluid accumulation.
The early diagnosis of a pleural disease and its cause is vital, not just for treating the condition itself but also for the treatment of the underlying cause, such as tuberculosis or cancer.