title: Differential diagnosis of usual interstitial pneumonia: when is it truly idiopathic?
abstract: Idiopathic pulmonary fibrosis (IPF), the most common and lethal of the idiopathic interstitial pneumonias, is defined by a radiological and/or pathological pattern of usual interstitial pneumonia (UIP). However, UIP is not synonymous with IPF as other clinical conditions may be associated with UIP, including chronic hypersensitivity pneumonitis, collagen vascular disease, drug toxicity, asbestosis, familial IPF and Hermansky-Pudlak syndrome. Differentiating IPF ("idiopathic UIP") from conditions that mimic IPF ("secondary UIP") has substantial therapeutic and prognostic implications. A number of radiological and histological clues may help distinguish IPF from other conditions with a UIP pattern of fibrosis, but their appreciation requires extensive expertise in interstitial lung disease as well as an integrated multidisciplinary approach involving pulmonologists, radiologists and pathologists. In addition, multidisciplinary discussions may decrease the time to initial IPF diagnosis and, thus, enable more timely management. This concept was strongly emphasised by the 2011 ATS/ERS/JRS/ALAT guidelines. This article highlights, with the aid of a clinical case, the difficulties in making a diagnosis of IPF in clinical practice. Yet, an accurate diagnosis is critical, particularly given the availability of drugs that may reduce the pace of functional decline and disease progression in IPF.
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland.
authors.forename: Wim A
authors.initials: WA
authors.lastname: Wuyts
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cavazza
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rossi
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bonella
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Sverzellati
authors.affiliation: Unit for Interstitial Lung Diseases, Dept of Pulmonary Medicine, University Hospitals Leuven, Leuven, Belgium. Operative Unit of Pathology, S. Maria Nuova Hospital, Reggio Emilia, Italy. Section of Pathology, University Hospital of Modena, Modena, Italy. Section of Diagnostic Imaging, Dept of Surgery, University of Parma, Parma, Italy. Interstitial and Rare Lung Disease Unit, Ruhrlandklinik, University Hospital, University of Duisburg-Essen, Germany. Medical University Clinic, Canton Hospital Baselland and University of Basel, Liestal, Switzerland. paolo.spagnolo@ksbl.ch.
authors.forename: Paolo
authors.initials: P
authors.lastname: Spagnolo
mesh_terms: D000542:Alveolitis, Extrinsic Allergic / Q000175:diagnosis; D000638:Amiodarone / Q000633:toxicity; D001172:Arthritis, Rheumatoid / Q000175:diagnosis; D003937:Diagnosis, Differential; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000175:diagnosis*; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000175:diagnosis; D011859:Radiography
chemical_list: D000638:Amiodarone