Inhaled (extrinsic)

➣ Injurious gases

• Smoke inhalation

• Centrilobular emphysema

• Chronic cadmium inhalation

➣ Inhaled particulates - Pneumoconiosis and Progressive Massive Fibrosis of the lung

• Silicosis - particle size 0.1-3.0 μm

• Coal worker pneumoconiosis - particle size 1-5 μm

• Radiation

• Miscellaneous pneumoconioses - cobalt, hard metal disease (tungsten carbide and cobalt), kaolinosis (kaolin),

bauxite pneumoconiosis (aluminum and silica), fuller's earth disease (calcium montmorillonite)

➣ Antigens

• Hypersensitivity pneumonitis - extrinsic allergic alveolitis

• Allergic bronchopulmonary aspergillosis

• Chronic eosinophilic pneumonia

➣ Granulomatous reactions

• Tuberculosis

• Sarcoidosis

• Berylliosis

• Langerhans cell histiocytosis

• Bronchocentric granulomatosis

Mechanical (intrinsic)

➣ Pleural stress

• Primary spontaneous pneumothorax

• Post-lobectomy air leak

• Ankylosing spondylitis

• Pleuropulmonary fibroelastosis (PPFE)

➣ Genetic disorders

• Cystic fibrosis: Impaired mucociliary clearance

• Alpha-1 antitrypsin deficiency: Lack of protease inhibition

• Marfan's syndrome: Defective fibrillin