Interstitial lung abnormality: The theory and clinical practice

Interstitial lung abnormalities or ILAs are an area of respiratory medicine (and, specifically, interstitial lung diseases) attracting considerable clinical and research interest. This has grown from a number of apparently disparate historical studies all of which have documented the presence of abnormalities on CT in asymptomatic patients and, more specifically, the identification of subtle subpleural reticulation, potentially likely to reflect lung fibrosis. Not surprisingly, greater attention in this area has been brought to bear since the publication of the successful antifibrotic drug therapy trials: the key question being, could the serendipitous identification of an ILA be the early or asymptomatic phase of idiopathic pulmonary fibrosis (IPF)? However, against this, it is clear that not all patients with an ILA will develop IPF — the prevalence of ILAs and IPF are orders of magnitude different, meaning that the majority of ILAs will not be the harbingers of future of IPF! That said, it is estimated that ~20% of ILAs will progress over a 2 year period. In this lecture a little of the history and clinical practice implications of ILAs and pulmonary fibrosis will be reviewed.