Idiopathic pulmonary fibrosis.
Idiopathic pulmonary fibrosis is a chronic and ultimately fatal disease characterized by a progressive decline in lung function. The term pulmonary fibrosis means scarring of lung tissue and is the cause of worsening dyspnea (shortness of breath). Fibrosis is usually associated with a poor prognosis.
The term idiopathic is used because the cause of pulmonary fibrosis is still unknown. IPF usually occurs in adult individuals of between 50 and 70 years of age, particularly those with a history of cigarette smoking, and affects more men than women.
- Signs and symptoms
In many patients, symptoms are present for a considerable time before diagnosis. The most common clinical features of IPF include the following: dry, non-productive cough on exertion; progressive exertional dyspnea (shortness of breath with exercise); dry, inspiratory bibasilar “velcro-like” crackles on auscultation (a crackling sound in the lungs during inhalation similar to Velcro being torn apart slowly, heard with a stethoscope); clubbing of the digits, a disfigurement of the finger tips or toes; abnormal pulmonary function test results, with evidence of restriction and impaired gas exchange. These features are due to chronic oxygen deficiency in blood.
If IPF is suspected, diagnosis can be challenging but a multidisciplinary approach involving a pulmonologist, radiologist and pathologist expert in interstitial lung disease has been shown to improve the accuracy of IPF diagnosis. Currently, a diagnosis of IPF requires:
- Exclusion of known causes of ILD, e.g., domestic and occupational environmental exposures, connective tissue disorders, or drug exposure/toxicity
- The presence of a typical radiological UIP pattern on HRCT.
Typical HRCT of the chest of IPF demonstrates fibrotic changes in both lungs, with a predilection for the bases and the periphery and it can identify UIP by the presence of:
- Reticular opacities, often associated with traction bronchiectasis
- Honeycombing manifested as cluster cystic airspaces, typically of comparable diameters (3–10 mm) but occasionally large. Usually sub-pleural and characterized by well-defined walls and disposed in at least two lines. Generally one line of cysts is not sufficient to define honeycombing
- Ground-glass opacities are common but less extensive than the reticulation
- Distribution characteristically basal and peripheral though often patchy.
Fibrosis is usually associated with a poor prognosis. A number of treatments have been investigated in the past for IPF, including interferon gamma-1β, bosentan, ambrisentan, and anticoagulants, but these are no longer considered effective treatment options. Many of these earlier studies were based on the hypothesis that IPF is an inflammatory disorder.