Etiology

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Pathophysiology

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Classifications

Asbestosis

• Etiology: Airborne asbestos fibers
• Population at risk:
  • Asbestos miners and millers
  • Brake linings and insulation manufactures
  • Ship construction workers
  • Demolishers
• Clinical features:
  • Symptoms typically develop 15–20 years after initial exposure.
  • Exertional dyspnea
  • Dry cough that transforms into productive cough
  • Digital clubbing
  • Ferruginous bodies in alveolar septa on histology
    • asbestos fiber becomes coated with iron and calcium

    Ingestion of these fibers by macrophages sets off a fibrogenic response via release of growth factors that promote collagen deposition by fibroblasts.

  • Complications
    • Lung cancer (smoking increases the risk): bronchogenic carcinoma is most common
    • Mesothelioma: rarely occurs without a history of asbestos exposure
• Chest x-ray:
  • Diffuse bilateral infiltrates predominantly in the lower lobes
  • Interstitial fibrosis
  • Calcified pleural plaques (usually indicate benign pleural disease)
• Microscopic
  • 

  This is the causative agent for asbestosis, a long, thin asbestos fiber. Some houses, business locations, and ships still contain building products with asbestos, particularly insulation materials, so care must be taken when doing remodelling or reconstruction.

Silicosis

• Etiology
  • Inhalation of crystalline silica, most commonly as dust
  • High-risk occupations for the development of silicosis include sandblasting, mining, and working in foundries

Mnemonic

To remember the high-risk occupations for the development of silicosis, think “I found (foundries) sand (sandblasting) on my (mining) window sill (silicosis)!”

• Clinical features
  • Chronic cough (often with sputum) and exertional dyspnea
  • Caplan syndrome: pneumoconiosis in combination with rheumatoid arthritis; characterized by rapid development of basilar nodules and mild obstruction of ventilation
• Chest x-ray
  • Eggshell calcification: well-defined sickle-shaped calcification of the rims of hilar lymph nodes
  • Bilateral diffuse ground glass opacities
  • Large number of rounded, solitary, small (≤ 1 cm in diameter) opacities particularly in the upper lobe of the lungs
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Clinical features

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Diagnostics

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Treatment

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