Current issues in the assessment of interstitial lung disease.

Interstitial lung diseases (ILDs) are chronic disorders of the lower respiratory tract, characterized by inflammation and derangement of the alveolar walls. The major functional consequence is the loss of alveolar capillary units and, thus, a limitation of oxygen transfer from air to blood. In recent years, new insights into many aspects of alveolitis as the basic pathological substrate of these diseases, the different inflammatory and immune competent effector cells and their role in the mechanisms of injury and repair have changed our concepts about the pathogenesis of ILD. New techniques, such as bronchoalveolar lavage and computed tomography, allow a better assessment of disease activity and extent of the underlying process. This review also discusses the problems of classification of ILD, and concentrates on issues of assessment and markers of disease activity. Treatment is not a topic of this review but better assessment of these disorders is probably a prerequisite of further progress in treatment and prognosis.