[How to investigate ... diffuse interstitial lung disease]

There are a large number of conditions of known or unknown causes that have a tendency to alveolar wall fibrosis. The patient usually presents with progressive dyspnoea and the chest radiograph shows bilateral shadows whereas physiological measurements show a restrictive defect. Because of implications with regard to treatment and prognosis, diagnosis and staging of the disease are important. Computed tomography ("high resolution") and bronchoalveolar lavage are very useful at all stages of management of interstitial lung disease.