NSIP: A diagnosis?

Introduction. Nonspecific interstitial pneumonia (NSIP) is the most discussed entity in the group of idiopathic interstitial pneumonias. Recognized in 2002 by the American Thoracic Society and the European Respiratory Society as a provisional diagnosis, NSIP may be idiopathic or associated with a number of clinical settings. Objective. The objective of this study was to determine the proportion of strictly idiopathic NSIP among a cohort of patients whose initial lung CT scan considered NSIP as a possible diagnosis. Method. 73 adult patients with an initial CT pattern of NSIP were selected in our database of adult patients with ILD (1998-2011) and were enrolled in a monocentric retrospective study. Anamnestic, clinical, functional, biological and pathological data were reviewed for each patient as well as the evolution of disease. Results. In only 21 patients of 73 (28.8%), a definitive diagnosis of idiopathic NSIP could be retained. In 10 of 21, an open lung biopsy was performed and showed cellular NSIP in 2, and fibrous NSIP in 8. In the remaining 52 patients (71.2%) an alternative diagnosis could be made, most frequently an underlying connective tissue disease (n= 22, 30.1%) and idiopathic pulmonary fibrosis (n=12, 16.4%). The other diagnoses include hypersensitivity pneumonitis (n=7, 9.6%), drug-induced lung disease (n=4, 5.5%), sarcoidosis (n=2, 2.7%), asbestosis (n=1, 1.4%), a sequel of ARDS (n=1, 1.4%), LIP (n=1, 1.4%) and a RBILD (n=1, 1.4%). Conclusion. This study demonstrates that idiopathic NSIP is a rare condition among patients presenting a radiological NSIP pattern. Therefore an integrated multidisciplinary approach is recommended in order to diagnose alternative/associated diseases needing for most of them a specific treatment.