1. Interstitial lung disease (ILD for short), also known as diffuse parenchymal lung disease (DPLD for short), pulmonary (interstitial) fibrosis or interstitial pneumonia. The so-called pulmonary fibrosis is the replacement of normal lung tissue by scar tissue, as in the case of scarring after a skin break. 2, scar formation thickens the interstitial lung, and it becomes difficult for oxygen to be transferred from the alveoli to the blood. Low oxygen in the blood leads to shortness of breath and decreased activity tolerance in patients with pulmonary fibrosis. 3, pulmonary fibrosis is a general term for a group of diseases; it has been found to include more than 200 different diseases, all of which have a common feature – namely, they cause scar formation in the lungs.