What is pleural parenchymal scarring in the upper lung?

Scaring sack. Scar tissue in pleural sac which surrounds the lung from prior infection or trauma.
History. Pleural scarring is using the result of an infection in the past that has healed. It could have been anything from pneumonia to TB to a myriad of other causes. It should be followed by xray or ct scan at intervals to make sure it is not increasing.