Overview Definition inhalation of small dust particles (coni = latin for dust) Pathophysiology varied and based on the type of dust fibrogenicity coal (least), asbestos, silica, and beryllium (most) region of respiratory tract involved (and mechanism of clearance) depends on particle size small particles affect alveoli (< 2 microns) phagocytosed by macrophages intermediate particles affect respiratory bronchioles ( > 2 microns but < 10 microns) cleared by mucociliary transport large particles are trapped in the upper respiratory tract all result in interstitial fibrosis ↑ incidence of cor pulmonale due to pulmonary hypertension Coal workers pneumoconiosis (CWP) Epidemiology workers of coal mines and inhabitants of large cities Pathology affects upper lobes (high ventilation) macrophages phagocytose particles ("dust cells") Sequelae no association with lung cancer simple CWP like smoking, can produce centrilobular emphysema 1 cm fibrotic centers complicated CWP 1-2 cm fibrotic centers Caplan's syndrome CWP + rheumatoid nodules in lungs Asbestosis Epidemiology workers in shipbuilding, roofing, and plumbing industries asbestos used for insulation Pathology affects lower lobes including the entire respiratory unit presence of asbestos bodies (aka ferruginous bodies) golden-brown fusiform rods (due to iron and protein deposition) resemble dumbbells → made of iron! located inside macrophages Sequelae calcified pleural plaques in the diaphragm and posterolateral mid lung ↑ incidence of bronchogenic carcinoma and mesothelioma bronchogenic carcinoma more common than mesothelioma mesothelioma takes longer time to develop (25-40 years) so is less common smoking has no effect on mesothelium, but amplifies the risk of bronchogenic carcinoma when combined with asbestos no association with TB may also result in Caplan's syndrome Silicosis Epidemiology workers in foundries, sandblasting, and mining industries Pathology affects upper lobes macrophages activated by silica (quartz) release fibrogenic cytokines biopsy shows silica particles (birefringent) surrounded by collagen "eggshell" calcification of hilar lymph nodes Sequelae may impair macrophage function ↑ susceptibility to TB ↑ incidence of primary lung cancer Berylliosis Epidemiology aerospace or nuclear industry workers Pathology noncaseating granulomas, nodular infiltrates, and enlarged lymph nodes resembles sarcoidosis Sequelae ↑ risk for primary lung cancer