Sarcoidosis: This is a rare condition that causes small patches of granular tissue, called granulomas, to form in the organs of the body, including the lungs.Idiopathic pulmonary fibrosis (IPF): This is a condition in which lung tissues become thick and stiff for unknown reasons.Pneumonia: The infection can also cause parenchymal inflammation (sometimes referred to as 'interstitial pneumonia').Asbestosis: This is a condition that causes scarring of the lungs due to prolonged exposure to asbestos fibers in the air.Pulmonary edema: This is the swelling of the lungs due to the overload of fluid in tissues (sometimes referred to as 'wet lung').Interstitial lung disease (ILD): This is an umbrella term used for a large group of diseases that cause scarring (fibrosis) of the lungs.