Pleural effusions due to which etiology are typically exudative?

• A. Malignancy
• B. Congestive heart failure
• C. Nephrotic syndrome
• D. Cirrhosis

Answer: (A)

Light's criteria distinguish exudative from transudative pleural effusions by the protein and LDH content of the fluid relative to serum. Exudates arise when the pleural surfaces are inflamed or invaded, increasing capillary permeability or impairing lymphatic drainage.

Malignancy fits this pattern best because tumor-related inflammation and direct involvement of the pleura raise vascular permeability and hinder lymphatic clearance, leading to high-protein pleural fluid and often elevated LDH. The other conditions listed—congestive heart failure, nephrotic syndrome, and cirrhosis—tend to produce transudates driven by systemic forces: elevated hydrostatic pressure in heart failure; low serum oncotic pressure from hypoalbuminemia in nephrotic syndrome and cirrhosis, and related mechanisms, which typically yield lower-protein, lower-LDH fluid.

So the pleural effusion due to malignancy is typically exudative.