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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
  • asbestosbodEpidemiology
    • 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
  • silicosisEpidemiology
    • 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 
 

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