LUNG DISEASES CAUSED BY INHALED DUST

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I. HYPERSENSITIVITY PNEUMONITIS (HSP)
II. PNEUMOCONIOSES
III. ASBESTOSIS AND SILICOSIS
IV. OTHERS

QUESTIONS TO CONSIDER AS LEARNING OBJECTIVES:

• This State is world renowned for its rich deposits of granite, marble, slate, asbestos and talc.
  
• What is pneumoniosis.
  
• This element is the most common constituent of the dusts known to produce lung disease.
  
• Acute exposure to silica, for instance in sandblasters, may produce this pattern on chest X-ray.
  
• Chronic silicosis has this gross appearance in the lung.
  
• The pathogenetic mechanism for the production of lung fibrosis in both silicosis and asbestosis has this cell at its center.
  
• Asbestos fibers tend to impact on this area of the lung.
  
• This highly malignant tumor is associated with exposure to thecroccidolite form of this mineral.
  

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I. HYPERSENSITIVITY PNEUMONITIS (HSP)

HSP represents the lung's allergic response to a variety of inhaled organic dusts. Farmer's lung is the classic example of hypersensitivity pneumonitis.

• Left unchecked, hypersensitivity pneumonitis can lead to progressive lung fibrosis and death.
  
• Once diagnosed, patients with HSP can be "cured" of their condition by avoiding the offending environment or eliminating the allergen triggering the lung injury.

II. PNEUMOCONIOSES

Inorganic dusts, primarily from mining, cause a number of characteristic acute and chronic lung diseases. The diseases together are referred to as the pneumoconioses.

• Pneumoconioses represent the result of conflict between the mineral world and living tissues.
  
• The dose, composition, mineral solubility and simultaneous effects of co-irritants (like smoking) all influence the development of pneumoconioses.
  
• Coal workers pneumoconiosis is subdivided into three types.

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III. ASBESTOSIS AND SILICOSIS

Two important contrasting examples of pneumoconioses are silicosis and asbestosis.

• Silicosis is caused by inhalation of crystalline and non-crystalline (amorphous) silica.
  
• Asbestosis is caused by inhalation of the fibrous silicate asbestos.
  
• Acute silicosis may occur in sandblasting when protective gear is not used. Within hours, acute respiratory distress ensues and diffuse bilateral "white out" of the chest X-ray is seen. Resolution occurs with variable amounts of lung fibrosis.
  
• Chronic silicosis is more common than the acute form. Here the lungs develop tiny fibrous nodules, initially in the upper zones of the lungs.
  
  • The disease begins within the alveoli where the tiny silica particles are deposited. Macrophages engulf the particles and recruit neutrophils and fibroblasts.
  • With continued exposure, nodules appear throughout the lungs and small nodules begin to coalesce into larger ones. The lung in between nodules becomes emphysematous or atelectatic. Nodules may calcify.
    
• Asbestosis also causes lung fibrosis, but the thread-like asbestos fibers tend to impact at airway branch points where they cause fibrosis. Asbestos exposure also carries certain risks for the development of lung cancer and a rare highly malignant neoplasm of the pleura known as mesothelioma. Even brief and minimal exposure to certain forms of asbestos (croccidolite or "blue" asbestos) can lead to the development of mesothelioma, usually 25-30 years after initial contact.

IV. OTHERS

• Berylliosis
  
• Caplan's Syndrome
  

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[ Anatomy, Embryology and Physiology of the Lung | Edema, Embolism, Infarction, and Pulmonary Hypertension | Lung Infections | Adult Respiratory Distress Syndrome (ARDS) and Chronic Interstitial Lung Disease | Airway Diseases COPD | Lung Disease Caused by Inhaled Dust | Lung Cancer ]

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[ CATS Home | About CATS | CATS Teaching Modules | UVM Department of Pathology | Other Pathology Sites | UVM College of Medicine | UVM ]

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Questions? Comments? Send a message to the CATS guru: jkessler@salus.uvm.edu