Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failure, pneumothorax, and lung cancer.Causes include environmental pollution, certain medications, connective tissue diseases, infections, and interstitial lung diseases. Idiopathic pulmonary fibrosis (IPF), an interstitial lung disease of unknown cause, is most common. Diagnosis may be based on symptoms, medical imaging, lung biopsy, and lung function tests.There is no cure and there are limited treatment options available. Treatment is directed towards efforts to improve symptoms and may include oxygen therapy and pulmonary rehabilitation. Certain medications may be used to try to slow the worsening of scarring. Lung transplantation may occasionally be an option. At least 5 million people are affected globally. Life expectancy is generally less than five years. Signs and symptoms
Symptoms of pulmonary fibrosis are mainly:
Shortness of breath, particularly with exertion
Chronic dry, hacking coughing
Fatigue and weakness
Chest discomfort including chest pain
Loss of appetite and rapid weight lossPulmonary fibrosis is suggested by a history of progressive shortness of breath (dyspnea) with exertion. Sometimes fine inspiratory crackles can be heard at the lung bases on auscultation. A chest X-ray may or may not be abnormal, but high-resolution CT will frequently demonstrate abnormalities. Cause
Pulmonary fibrosis may be a secondary effect of other diseases. Most of these are classified as interstitial lung diseases.
Examples include autoimmune disorders, viral infections and bacterial infection like tuberculosis which may cause fibrotic changes in both lungs upper or lower  lobes and other microscopic injuries to the lung. However, pulmonary fibrosis can also appear without any known cause. In this case,  it is termed "idiopathic". Most idiopathic cases are diagnosed as idiopathic pulmonary fibrosis. This is a diagnosis of exclusion of a characteristic set of histologic/pathologic features known as usual interstitial pneumonia (UIP). In either case, there is a growing body of evidence which points to a genetic predisposition in a subset of patients. For example, a mutation in surfactant protein C (SP-C) has been found to exist in some families with a history of pulmonary fibrosis. Autosomal dominant mutations in the TERC or TERT genes, which encode telomerase, have been identified in about 15 percent of pulmonary fibrosis patients.Diseases and conditions that may cause pulmonary fibrosis as a secondary effect include:
Inhalation of environmental and occupational pollutants, such as metals in asbestosis, silicosis and exposure to certain gases. Coal miners, ship workers and sand blasters among others are at higher risk. Hypersensitivity pneumonitis, most often resulting from inhaling dust contaminated with bacterial, fungal, or animal products
Cigarette smoking can increase the risk or make the illness worse
Some typical connective tissue diseases such as rheumatoid arthritis, ankylosing spondylitis, SLE and scleroderma
Other diseases that involve connective tissue, such as sarcoidosis and granulomatosis with polyangiitis
Infections, including COVID-19
Certain medications, e.g.