Pulmonary or interstitial fibrosis is a descriptive term given when there is an excess of fibrotic tissue in the 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.
Fibrosis in the lung is a process that occurs in the interstitium. Pulmonary fibrosis can be localized, segmental, lobar, or affect the entirety of the lung(s). 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
- airway-centered interstitial fibrosis
- chronic conditions
- polymyalgia rheumatica (occasional case reports )
- 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
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