Interstitial Pneumonias

The idiopathic interstitial pneumonias are part of the wide spectrum of diffuse parenchymal lung diseases (Fig. 19.1).1 While recognition of diffuse interstitial pulmonary fibrosis can be traced back to studies by Hamman and Rich2 in the 1930s and 1940s, they were first classified as a set of histopathologic patterns in the 1960s by Liebow and Carrington3 into usual interstitial pneumonia (UIP), desquamative interstitial pneumonia (DIP), bronchiolitis obliterans with interstitial pneumonia (BIP), giant cell interstitial pneumonia (GIP) and lymphoid interstitial pneumonia (LIP). At about the same time, Scadding4 in the United Kingdom proposed the term fibrosing alveolitis, suggesting (incorrectly) that DIP and UIP were early and late phases of a single disorder.5 There has subsequently been much discussion and controversy over what patterns should be included in such a classification system, in terms of both histology and what these patterns represent regarding clinical disease. As a result, some patterns have now been categorized according to their recognized causes; for example, GIP has been reclassified as a pneumoconiosis, the cause being exposure to cobalt during the production of hard metals or during diamond polishing (see Chapter 26).6,7