Parenchymal lung disease, also known as interstitial lung disease, refers to a group of lung disorders that affect the parenchymal tissue or interstitium of the lungs. These diseases can cause scarring, inflammation, and thickening of the lung tissue, leading to impaired lung function and difficulty breathing. Some common types of parenchymal lung disease include idiopathic pulmonary fibrosis, sarcoidosis, and occupational lung diseases. Symptoms can vary but often include shortness of breath, cough, and fatigue. Diagnosis typically involves a combination of medical history, physical examination, imaging tests (such as chest X-rays or CT scans), and pulmonary function tests. Treatment for parenchymal lung disease often focuses on managing symptoms, slowing disease progression, and improving overall lung function. This may involve medications, pulmonary rehabilitation, oxygen therapy, and in some cases, lung transplantation. Research in this area is ongoing to better understand the causes and mechanisms of these diseases, as well as to develop more effective treatments.