ABSTRACT
INTRODUCTION Definition and Epidemiology The diffuse parenchymal lung diseases (DPLD), often collectively referred to as the inter stitial lung diseases (ILDs), are a heterogeneous group of disorders classified together because of similar clinical, roentgenographic, physiological, or pathological manifesta tions. The most common known causes of DPLD are related to occupational and environ mental exposures, especially to inorganic or organic dusts. Sarcoidosis, idiopathic pulmo nary fibrosis (IPF), and pulmonary fibrosis associated with connective tissue diseases are the most common ILDs of unknown etiology. In this chapter, the illnesses of known cause are presented first, followed by diseases of unknown etiology.
