Fibrosis with emphysema.

The concept of fibrosis with emphysema is confused by the existence of two very different clinical/pathological scenarios: first, cases in which a diffuse fibrosing interstitial pneumonia, most commonly usual interstitial pneumonia (UIP), occurs in a patient with emphysema. This combination is largely of clinical interest because of its effects on pulmonary function and pulmonary hypertension, but can produce unusual appearances in surgical lung biopsies when the fibrotic areas are wrapped around emphysematous spaces. However, the underlying morphology of emphysema and UIP or other interstitial lung disease remains unchanged. Radiological consultation is often helpful to show that the patient has both lesions; secondly, cases in which there is localized fibrosis that is part of emphysema, or related to respiratory bronchiolitis, or both. These lesions have been called 'respiratory bronchiolitis' (RB), 'respiratory bronchiolitis-interstitial lung disease' (RB-ILD), 'airspace enlargement with fibrosis', 'RB-ILD with fibrosis' and 'clinically occult interstitial fibrosis in smokers', but are probably all the same entity. Such changes are associated only rarely with the physiological or radiological features of an interstitial lung disease. Care should be taken when describing these lesions in biopsies so as not to give the impression that a diffuse interstitial lung disease is present.