Introduction

In diffuse fibrotic lung disease, open and blinded therapeutic trials have largely been confined to patients with idiopathic pulmonary fibrosis (IPF, synonymous with cryptogenic fibrosing alveolitis). The results of these studies and the anecdotal experience of chest physicians throughout the world have demonstrated that current treatments do not prevent the progression of IPF in most cases. However, in the last 5 years, there has been a major change in the overall conceptual approach to therapy. Previously, it had been argued in IPF (and other diffuse fibrotic lung diseases) that inflammation precedes and leads to fibrosis). Thus, current treatments, which are largely ineffective, are based upon the suppression of inflammation (usually by means of corticosteroid and immunosuppressive therapy). The notion of a histopathological continuum in IPF, in which inflammation and fibrosis are seen as closely inter-related, was reinforced by the use of the terms ‘desquamative interstitial pneumonia’ (DIP) and ‘usual interstitial pneumonia’ (UIP). This terminology, coined in the 1970s, was thought by many to denote the early inflammatory phase of disease and the later irreversible fibrotic form, respectively.

More recently, the view that inflammation infallibly leads to fibrosis has been challenged. As discussed later, it is now widely accepted that DIP and UIP are separate disorders, and that there is no evidence that DIP progresses to UIP.