Pleural calcification with persistent effusion.

Chronic persistent pleural effusions were observed in 22 out of 140 patients with calcification involving the parietal and visceral pleurae. If no effusion is present, the two adjacent calcified pleurae may adhere together; and conversely, in the presence of fluid the pleural layers are separated, producing more than one linear density on the radiograph. Pleural thickening can exceed 2 cm. In patients with calcified fibrothorax, the calcified parietal pleura is separated from the inner thoracic wall by fat whether an effusion is present or not. The value of CT and sonography in the detection of persistent effusions is discussed.