It is a general category that includes many different lung conditions. All interstitial lung diseases affect the interstitium, a part of the lungs anatomic structure.
Sarcoidosisis an inflammatory disease that affects multiple organs in the body, but mostly the lungs and lymph glands. If untreated, causes permanent damage to affected organ Idiopathic.
Pulmonary Fibrosis (IPF) is defined as a specific form of chronic, fatal, progressive fibrosing interstitial pneumonia of unknown cause, primarily occurring in older adults and limited to the lungs. Other are NSIP, HSP etc.