Inflammation is simply a collection of white blood cells. In an infection, the white blood cells kill bacteria by powerful substances they possess. In this manner, the body is helped by inflammation. However, white blood cells can, in some instances, damage normal tissue also, and this then results in fibrosis or scarring. Also, a disease called hypersensitivity pneumonitis, an allergic disorder, may also cause lung scarring.
Some disorders are idiopathic, meaning there is no easily identifiable cause for the disease.
The initial event that begins the process of lung inflammation and subsequent lung scarring is, for the most part, still a mystery in these diseases of unknown cause. We now have a good understanding, however, of how the body reacts to try to ward off these diseases in the lung. This knowledge forms the basis for deciding when and how to treat lung scarring. The interstitium is the scientific term for the tissue which lines and supports all of the very tiny air sacs which make up the lung. In these small air sacs is where oxygen enters the blood and waste products like carbon dioxide leave the blood.