ERS | monograph Introduction Wim A. Wuyts 1 , Vincent Cottin 2 , Paolo Spagnolo3 and Athol U. Wells4 @ERSpublications Pulmonary manifestations of systemic diseases must be considered forensically and not managed by focus on a single organ. This book provides expert clinical guidance on difficult diseases, aiding respiratory and nonrespiratory physicians. http://bit.ly/36HBY4i ILDs comprise ⩾200 separate lung disorders. The interest in these diseases has risen enormously in recent years. A large body of basic and clinical research has greatly increased our understanding of the pathogenesis of IPF and, to a lesser extent, non-IPF fibrotic ILDs. Validated and emerging antifibrotic treatments for IPF are likely to be efficacious in other pulmonary fibrotic disorders exhibiting IPF-like disease progression. The ILD field is now evolving rapidly, with major implications for practical management. However, it is important that the multiplicity of less prevalent ILDs, including those with predominantly inflammatory and mixed inflammatory/fibrotic phenotypes, are not lumped indiscriminately with inexorably progressive pulmonary fibrosis. Individual diseases must be appraised forensically. In this regard, pulmonary manifestations of systemic diseases cannot be adequately managed by focusing solely on ILDs but pose unique problems for physicians. Many systemic diseases are treated by non-respiratory specialists who do not always have expertise in assimilating pulmonary signs, symptoms and tests. Furthermore, many of these entities are extremely uncommon and this is often challenging for respiratory physicians. This Monograph, dedicated to the pulmonary manifestations of systemic disorders, provides background information and expert clinical guidance on these difficult diseases, which will be helpful to respiratory physicians and non-respiratory specialists alike. The initial chapter considers the diagnostic issues in these diseases [1]. As a first step, collaboration between different experts in medicine is a requisite in these diseases this is a challenge, but for our patients the best is not enough. In order to establish the most confident diagnosis, collaboration is necessary as data originate from different experts in the field. The next step is to find a way to communicate these results and integrate them into the specific case for the individual patient. The best way is multidisciplinary discussion. This has been extensively tested over the years and has now become the Copyright ©ERS 2019. Print ISBN: 978-1-84984-111-5. Online ISBN: 978-1-84984-112-2. Print ISSN: 2312-508X. Online ISSN: 2312-5098. Correspondence: Wim A. Wuyts. Unit for Interstitial Lung Diseases, Dept of Respiratory Medicine, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium. E-mail: wim.wuyts@uzleuven.be 1 Respiratory Medicine, Unit for Interstitial Lung diseases, University Hospitals Leuven, Leuven, Belgium. 2 Service de Pneumologie, Hopital L. Pradel, Lyon, France. 3 University of Padova School of Medicine and Surgery, Padova, Italy. 4 Interstitial Lung Disease, Royal Brompton Hospital, London, UK. https://doi.org/10.1183/2312508X.10033219 ix