Idiopathic interstitial fibrosis.

The lung has only a limited pattern of response to injury. Idiopathic interstitial fibrosis is a descriptive term, describing the end stage of one pattern of pulmonary fibrosis in which the inflammation lies within the structure of the alveolar walls and around vessels and bronchioli, in the interstitium. The disease is characteristically subpleural in distribution and provides a marked restrictive consequence on pulmonary function which progresses to hypoxic core pulmonale. This is despite the apparent normality of much of the lung at autopsy. Six to fifteen percent develop lung cancer, the proportion depending on the autopsy rate. A nonspecific nature of the changes limits the diagnostic value of transbronchial biopsy, open lung biopsy may be of value in assessing and grading the disease in relationship to therapy.