• Pneumoconiosis from fibrous silicate minerals
  
• Peripheral lower zone irregular opacities
  
• 25% have associated pleural plaques
  
• HRCT
  
  • Subpleural curvilinear lines
    
  • Interlobular lines (Short) and parenchymal (long) lines
    
  • Centriacinar nodules (peribronchial firbrosis)
    

Chest Radiograph

• May be normal
  
• Peripheral lower zone predominance
  
• Irregular reticular opacities
  
• ILO classification: s,t,u opacities
  
• Late: end-stage honeycombing
  
• May have pleural plaques (25%)
  
• Lung cancer: lower zone predominance

CT/HRCT

• More sensitive than chest radiograph
  
• Interlobular septal thickening (short lines)
  
• Subpleural lines
  
• Parenchymal bands
  
• Centriacinar nodules (peribronchial fibrosis)
  
• Honeycombing
  
• Ground glass opacities
  
  • Nonspecific
    
  • Atelectasis (reversible prone position)
    
  • Early fibrosis
    

• Idiopathic pulmonary fibrosis
  
• Scleroderma
  
• Rheumatoid arthritis
  
• Hypersensitivity pneumonitis
  
• Lymphangitic tumor
  
• Cytotoxic drug reaction

• Fibrosis + asbestos bodies equals asbestosis
  
• 2 types of fibers
  
  • Serpentine (chrysotile, 90% commercial asbestos)
    
    • Curly, wavy fiber
      
    • Long (>100 µm)
      
    • Diameter (20 – 40 µm)
      
  • Amphibole (amosite, crocidolite)
    
    • Straight, rigid fiber
      
    • Variable length diameter
      
    • Aspect ration (length/width) > 3:1
      
• Retention: long thin fibers > short thick fibers
  
• Asbestos (Ferruginous) bodies
  
  • Hemosiderin coated fiber (mostly amphibole)
    
  • Incompletely phagocytized by macrophages
    
  • Not pathognomonic for asbestosis
    
  • Coated fibers < uncoated fibers
    
  • Not correlated with fibrosis
    
• Early fibrosis: centered on respiratory bronchioles
  
• Patchy distribution
  
• Fibrosis associated with > 1 million fibers/gm lung tissue
  
• Honeycombing: subpleural distribution
  

• Mills, insulation, shipyards, construction
  
• Latent period 20-30 years
  
• Multiplicative risk factor for lung cancer
  
• Clinical diagnosis (4 of 5 criteria)
  
  • Exposure history
    
  • Dyspnea on exertion
    
  • Inspiratory crackles
    
  • Abnormal compatible chest radiograph
    
  • Restrictive pattern pulmonary function
    
• No treatment, stop smoking, consider lung cancer screening
  
• Most die lung cancer

Aberle DR , Balmes JR. Computed tomography of asbestos-related pulmonary parenchymal and pleural diseases Clin Chest Med 12:115-131, 1991
Akira M, Yokoyama K, Yamamoto S, et al. Early asbestosis: evaluation with high-resolution CT Radiology 178:409-416, 1991