- Silicosis
| Inhaled silica dust produces a fibrogenic response in a nodular pattern ("silicotic nodules")
| - Asbestosis
| Inhaled asbestos fibers become encrusted with calcium and iron ("ferruginous bodies"). Pleural plaques (often diaphgragmatic) and interstitial fibrosis occur. The risk of bronchogenic carcinoma is increased, particularly in smokers. Mesotheliomas can occur but are rare
| - Coal Worker's Pneumoconiosis
| The amount of carbonaeous dust inhaled to produce CWP is far in excess of the simple anthracosis that nearly everyone has. "Coal macules" induce fibrosis
| - Berylliosis
| In this rare condition the inhaled dusts contain beryllium that produces a granulomatous response with "sarcoid-like" granulomas
| | Sarcoidosis | This idiopathic condition is characterized by granuloma formation. The granulomas are typically non-caseating. Hilar lymph nodes are nearly always involved and can become quite large
| | Idiopathic Pulmonary Fibrosis | IPF includes a variety of entities, of which usual interstitial pneumonitis (UIP) is most common, all characterized by progressive fibrosis
| | Autoimmune Conditions | The damage can occur with autoantibodies that produce inflammation involving mesothelial surfaces and vascular basement membranes
| - Scleroderma
| Diffuse scleroderma can lead to interstitial fibrosis with minimal inflammation
| - Rheumatoid Arthritis
| Focal necrotizing granulomatous inflammation ("rheumatoid nodules") can form on pleural surfaces and in the parenchyma
| - Wegener's Granulomatosis
| There is vasculitis involving pulmonary arteries
| | Goodpasture Syndrome | There is antiglomerular basement membrane antibody (that also is directed at pulmonary capillary basement membranes) that causes a form of type II hypersensitivity reaction which damages alveolar capillary basement membranes with subsequent hemorrhage into alveoli
| | Therapeutic Complications | The lungs can be damaged by radiation and pharmacologic agents used to treat various conditions
| - Radiation
| External beam radiation therapy, particularly mantle radiation for Hodgkin disease, can result in progressive fibrosis of interstitium and pleura
| - Drugs
| The chemotherapeutic agents bleomycin and busulfan in particular induce pulmonary fibrosis
| | Hypersensitivity Pneumonitis | Inhaled allergens produce localized antigen-antibody complexes that lead to an acute extrinsic allergic alveolitis, a form of type III hypersensitivity. If chronic, there can be a type IV hypersensitivity response
| | Diffuse Alveolar Damage | DAD is an acute process that can result from any type of severe lung injury. Clinically, it is known as adult respiratory distress syndrome (ARDS)
| - Phase 1
| In the first few days following an acute lung injury, there is exudation with hyaline membrane formation in alveoli
| - Phase 2
| Toward the end of the first week following acute lung injury, pulmonary macrophages proliferate and interstitial edema with some mixed inflammatory infiltrates occurs
| - Phase 3
| Over weeks to months following acute lung injury, there is increasing interstitial fibrosis leading to "honeycomb" change
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