Diffuse interstitial lung diseases

Diffuse interstitial lung diseases (ILD) constitute a heterogenous group of processes which have in common reticular or nodular, reticulonodular or linear patterns on chest roentgenogram. They are characterized by a diffuse infiltration of alveolar walls by inflammatory or malignant cells, connective tissue or fluid. About 100 entities have been ascribed to diffuse interstitial lung disease. The aim of the clinician is to confirm the diagnosis of ILD, to elicit an entity from history, symptoms, physical examination, chest roentgenogram, pulmonary function and laboratory data in order to plan treatment. Therefore, the pattern may include malignant, infectious, and cardiac diseases with roentgenographic reticulonodular patterns, i.e lymphangitic carcinomatosis, alveolar cell carcinoma, miliary tuberculosis, infection in immunosuppressed patients, and congestion of the lungs secondary to congestive heart failure. In fact, the term ILD usually excludes this heterogenous group of diseases and is focused on inflammatory processes in which the common outcome is dominated by fibrotic lung disorder. They are also commonly called pulmonary fibrosis and will be developed in this chapter.