Exudative pleural effusion is a type of pleural effusion characterized by the accumulation of fluid in the pleural space due to an increase in the permeability of the pleural membrane. This type of pleural effusion is often associated with inflammatory conditions, infections, and malignancies.

Some of the common causes of exudative pleural effusion include:

1. Infections: Bacterial, viral, and fungal infections can cause inflammation of the pleura, leading to the accumulation of fluid in the pleural space. Examples include pneumonia, tuberculosis, and empyema.

2. Malignancies: Cancerous cells can invade the pleura, causing inflammation and fluid accumulation. Common malignancies associated with exudative pleural effusion include lung cancer, breast cancer, and lymphoma.

3. Autoimmune diseases: Conditions such as rheumatoid arthritis, lupus, and sarcoidosis can cause inflammation of the pleura, leading to exudative pleural effusion.

4. Heart failure: In some cases, heart failure can cause exudative pleural effusion due to increased pressure in the blood vessels of the lungs, leading to leakage of fluid into the pleural space.

5. Kidney failure: In rare cases, kidney failure can cause exudative pleural effusion due to the accumulation of fluid in the body.

The diagnosis of exudative pleural effusion is made by analyzing the fluid obtained through thoracentesis. The fluid is classified as exudative if it meets at least one of the following criteria:

1. Protein level greater than 0.5 g/dL or a ratio of pleural fluid protein to serum protein greater than 0.5
2. Lactate dehydrogenase (LDH) level greater than two-thirds of the upper limit of normal for serum LDH
3. Pleural fluid LDH level greater than the upper limit of normal for serum LDH.

Treatment of exudative pleural effusion depends on the underlying cause. In some cases, the effusion may resolve on its own with conservative management, such as rest and pain management. However, if the effusion is causing significant respiratory distress or is associated with an underlying condition such as cancer, treatment may involve draining the fluid through a chest tube or performing a pleurodesis to prevent the recurrence of the effusion.

In conclusion, exudative pleural effusion is a type of pleural effusion that is often associated with inflammatory conditions, infections, and malignancies. The diagnosis is made by analyzing the fluid obtained through thoracentesis, and treatment depends on the underlying cause.