standard approach for evaluation of complex ILDs. We would argue that this manner of discussion should be transferred to other domains and that more non-pulmonary specialists should be added to teams. This exchange of expertise works both ways: on the one hand, it is beneficial as it raises awareness about the lungs amongst specialists in other fields, such as rheumatologists, general internists, nephrologists… On the other hand, we as pulmonologist could also learn from them in increasing our suspicion of the symptoms and signs of underlying CTD, but also by being more specific in the evaluation of only subtle biochemical abnormalities, without clinical counterpart. Another important topic covered in this Monograph is PFTs, the cornerstone of diagnosis and follow-up [2]. At first sight it might seem odd that this is covered in a book mainly intended for pulmonologists. But we are convinced that in modern literature, there are few manuscripts that bring together current knowledge and particularly the pitfalls in PFTs. We also hope that this book will be picked up by experts outside the field of pulmonary medicine so that they realise the value of PFTs, but also look for the necessary expertise within their team. The book goes on to discuss the contemporary techniques that are now in full development, such as quantitative CT analysis in ILD and the use of artificial intelligence on imaging of ILD [3]. This chapter provides a comprehensive overview of the possibilities now and in the future. In this Monograph, we have tried to cover a variety of interesting pulmonary manifestations of very different disease entities, such as CTDs, systemic vasculitis and others. The major CTDs covered are RA [4], inflammatory myopathies [5], SSc [6], Sjögren syndrome and mixed CTD [7], antiphospholipid syndrome [8] and finally, IPAF and undifferentiated CTD [9]. The chapters on systemic vasculitides comprise: microscopic polyangiitis and granulomatosis with polyangiitis [10], DAH [11], eosinophilic granulomatosis with polyangiitis [12], and pulmonary involvement in Takayasu arteritis and Behçet disease [13]. The chapters covering other diseases with extrathoracic involvement discuss bronchial and pulmonary involvement in inflammatory bowel diseases [14], the lung in liver disease [15], lung complications of neuromuscular diseases [16], amyloidosis and the lung [17], trafficking and lysosomal storage disorders (Hermansky–Pudlak, Gaucher, Niemann–Pick, Fabry, Lysinuric protein intolerance) [18], pulmonary involvement in haematological disorders and bone marrow transplant recipients [19], systemic histiocytic disorders (Langerhans and non-Langerhans cell histiocytosis, Erdheim–Chester and Rosai–Dorfman) [20], immunodeficiency [21], telomere syndrome and the lung [22], and finally, the pulmonary manifestations and management of sarcoidosis [23]. The Guest Editors very much hope that this Monograph will provide the reader with an interesting overview and update on the possible pulmonary involvement and specific treatment options of different systemic diseases. We sincerely hope that this book will be well received and will raise further interest in these diseases, leading to an increase in collaboration between different organ specialists and earlier diagnosis of patients confronted with very complex diseases that might turn their live upside down. We also hope that this book will serve as a catalyst to the development of more basic and clinical research in these intriguing diseases. x https://doi.org/10.1183/2312508X.10033219