Pleural thickening

The pleura is a layer of serosa that covers the lung surface and the inner side of the thorax. It is called the visceral and parietal pleura. The two layers of pleura surround a gap called the pleural cavity. Under normal circumstances, the pleural cavity contains only a small amount of serum, which acts as a lubricant, reduces the friction between the two layers of the pleura, and prevents adhesions.