ABSTRACT
There has been considerable confusion over the nomenclature of the idiopathic interstitial pneumonias. Some of this confusion has been resolved by the publication of the clinical-radiological-histopathological classification by the American Thoracic and European Respiratory Societies in 2002 Table 1. This classification is by no means the final word on the subject but does provide some order. Of the different and distinct disease entities defined, the most important clinical decision that needs to be made is whether the patient has idiopathic pulmonary fibrosis [IPF]. This diagnosis carries the prediction of a 2-3 year mean survival in marked contrast to the other diseases included in this new classification where survival is better and response to treatment generally more likely. Because the outcome in IPF is so much worse and because this has an obvious impact on the patient's management, it is the need to confirm or refute this diagnosis that drives the diagnostic algorithm in the idiopathic fibrosing lung diseases. The criteria used to define IPF are shown in Table 2 for patients either with or without a surgical lung biopsy