Pulmonary fibrosis is a descriptive term given when there is excess of fibrotic tissue in lung. It can occur in a wide range of clinical settings and can be precipitated by a multitude of causes. The term should not be confused with idiopathic pulmonary fibrosis which is a progressive fibrotic lung disease.
Pulmonary fibrosis can be localized, segmental, lobar, or affect the entirety of the lung(s).
Fibrosis in the lung is a process that occurs in the interstitium. It is therefore also termed interstitial fibrosis.
Among the many conditions associated with pulmonary fibrosis are:
- significant acute insult to the lungs
- inhaled substances
- radiation: radiation-induced pulmonary fibrosis
- congenital conditions
- autoimmune conditions
- connective tissue disorders
- granulomatous conditions
- sarcoidosis: pulmonary manifestations of sarcoidosis
- tuberculosis: pulmonary manifestations of tuberculosis
- granulomatosis with polyangiitis: pulmonary manifestations of granulomatosis with polyangiitis
- chronic conditions
- polymyalgia rheumatica (occasional case reports 6)
- medications: drug-induced lung disease
- combined pulmonary fibrosis and emphysema'
- some studies report thin-section CT findings associated with interstitial lung disease to some degree are frequently seen in "asymptomatic" elderly individuals 7,8
There are many features that can imply underlying pulmonary fibrosis, these include:
- traction bronchiectasis
- lung architectural distortion
- interlobular septal thickening: this feature is not specific for fibrosis
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