Diffuse parenchymal (interstitial) lung disease

What it is

Diffuse parenchymal lung diseases, also called diffuse interstitial lung diseases or interstitial lung diseases, are a generic term encompassing a broad range of largely unrelated conditions: more than 200 different diseases classified together because of similar clinical, radiographic, physiologic or pathologic manifestations. Most of these disorders are also associated with extensive alteration of alveolar and airway architecture.

Causes and risk

The group divides into disease of known causes or association, idiopathic interstitial pneumonia, granulomatous disease, and other forms. The known causes are connective tissue disease such as rheumatoid arthritis, scleroderma, Sjogrens, SLE and dermatomyositis or polymyositis; drug induced disease from methotrexate, bleomycin, amiodarone or nitrofurantoin; inhalational exposures such as asbestosis, silicosis, hypersensitivity pneumonitis and pneumoconiosis; and radiation exposures. The idiopathic interstitial pneumonias are chronic fibrosing (idiopathic pulmonary fibrosis and idiopathic non-specific interstitial pneumonia), acute or subacute (cryptogenic interstitial pneumonia and acute interstitial pneumonia), and smoking related (desquamative interstitial pneumonia and respiratory bronchiolitis interstitial lung disease). The granulomatous form is sarcoidosis, and other forms include LAM, PLCH, alveolar proteinosis and amyloidosis. Vasculitis such as granulomatosis with polyangiitis, and infections such as fungal disease, tuberculosis and viral pneumonia, are also listed.

The occupational exposures to look for are asbestos causing asbestosis, beryllium causing berylliosis, coal causing coal workers' pneumoconiosis, and silica causing silicosis. The environmental ones are birds, mold, and animals or hay.