Diffuse interstitial disease with pleural effusion

A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.01 millilitre per kilogram weight per hour, and is cleared by lymphatic absorption leaving behind only 5–15 millilitres of fluid, which helps maintaining a functional vacuum between the parietal and visceral pleurae. [Source: Wikipedia ]