The Guest Editors Wim Timens studied Medicine at the University of Groningen (Groningen, the Netherlands) and received his MD in 1983. After a short period as a research fellow, he followed the residency training programme at the Dept of Pathology, University Hospital Groningen, and was registered as a pathologist in 1990. In 1988, he received a PhD with his thesis on “Structure and function of the human spleen”. In 1990, Wim worked as a post-doc at the Cross-Cancer Institute (Edmonton, Canada), and later that year joined the fac- ulty of the Dept of Pathology, University Hospital Groningen. In 1992, he was appointed as an Associate Professor in this department, and in 1994 as a full Professor in Pathology. Although he started his career in haematopathology and immunopathology, areas in which he also started his research interests, Wim soon became very interested in and challenged by pulmonary pathology. Over the last 16 years, he has dedicated his diagnostic pathology work to the whole area of pulmonary diseases. He has worked on different research themes involving lung pathology, and has been involved in and leads many research projects, most with external funding and almost invariably in close collaboration with the Dept of Pulmonology and several other disciplines. Within the research themes, there is a strong focus on the pathogenesis of obstructive lung diseases, which is a main research area in the University Medical Center Groningen. He is a Co-Chair of the Groningen Research Institute on Asthma and COPD (GRIAC) and has been a member of the Scientific Board of the Netherlands Asthma Foundation for many years. Helmut H. Popper studied Medicine at the University of Graz, Medical Faculty (Graz, Austria) and received his MD in 1973. From 1973, he worked as an Assistant at the Institute of Pharmacology, University of Graz, but moved to the Pathology Dept in 1975. In 1984, Helmut finished his training with board certification in Pathology and became Associate Prof. of Pathology with residency at the Institute of Pathology. In 1986, he was appointed Head of the Laboratory of Environmental Pathology and in 1991 was certified for Cytopathology, becoming Prof. of Pathology in 1992. In 1999, Helmut received further certi- fication for Human Genetics and was appointed as Head of the Laboratories for Molecular Cytogenetics and Environmental & Respiratory Tract Pathology in 2000. In 1988 and 1989, he spent some time at the Lovelace Inhalation Toxicology Research Institute, Albuquerque (NM, USA), to learn methods in inhala- tion toxicology and research. His main focus is genetics in lung diseases with a special interest in lung can- cer and sarcoidosis. From 1999–2003 he served as Chair of the Pulmonary Pathology Working Group of the European Society of Pathology, and again from 2005–2007. Since 2001, Helmut has stood as Chair of an EU project on rare pulmonary diseases, and organised the establishment of the European case collection on rare pulmonary diseases. He is currently Co-Chair for the Latin American–European Pulmonary Pathology Working Group. He is also a member of the Editorial Board of Virchows Archiv, and an Associate Editor of Archives of Pathology & Laboratory Medicine. W. Timens H.H. Popper