ABSTRACT
Diffuse lung disease includes a wide range of parenchymal lung diseases that have infectious, inflammatory, malignant, drug, occupational/environmental, and other causes. Although many identifiable causes are recognized, the cause of most cases of diffuse lung disease in many published series is idiopathic. The clinical course may be acute or prolonged and may progress rapidly to life-threatening respiratory failure with death, or it may be indolent over many years. In most instances, a differential diagnosis can readily be formulated by obtaining the medical history, with emphasis on the nature of the symptoms, duration, and pertinent environmental, occupational, drug, and travel exposures. The physical examination, laboratory tests, pulmonary function tests (PFTs), chest radiography (CXR), and computed tomography (CT) often provide clues to the diagnosis. The diagnosis may be confirmed on clinical grounds but may also require bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy or open lung biopsy via video-assisted thoracoscopy (VATS).
