pneumoconiosis

Question 1

definition of pneumoconiosis

Answer 1

The pneumoconioses are a group of interstitial lung diseases, mostly of occupational origin, caused by the inhalation of mineral or metal dusts.

• Fibrosing interstitial lung disease caused by chronic inhalation of mineral dusts.
• Simple – Coalworker’s pneumoconiosis or silicosis (asymptomatic)
• Complicated – a pneumoconiosis (progressive massive fibrosis) = loss of lung func
• Asbestosis – a pneumoconiosis where diffuse parenchymal lung fibrosis occurs as a result of prolongued asbestos exposure
• Caplan’s syndrome The association between rheumatoid arthritis, pneumoconiosis, and pulmonary rheumatoid nodules.

Question 2

aetiology of pneumoconiosis

Answer 2

• inhalation of particles of coal dust (1-3um) over 15-20yrs, silica or asbestos (two main types of fibre: white asbestos and blue asbestos or crocidolite, the latter is more toxic).
• Silicosis – caused by inhalation of silica particles which are fibrogenic
  
  • A number of jobs may be associated with exposure, eg metal mining, stone quarrying, sandblasting, and pottery/ceramic manufacture.

Question 3

RF of pneumoconiosis

Answer 3

• Occupational exposure
  
  • Coal mining
  • Quarrying
  • Iron and steel foundries
  • Stone cutting
  • Sandblasting
  • Insulation industry
  • Plumbers
  • Ship builders
• Risk depends on extent of exposure, size, shape of particles and individual suspeptibility
• Smoking
• TB

Question 4

pathogenesis of pneumoconiosis

Answer 4

Coal worker’s

• Coal particles ingested by macrophages – release they’re enzymes = fibrosis

Progressive massive fibrosis is due to progression of coal worker’s

Complicated disease

• Large nodules in lung – dust particles (coal/silica) surrounded by layers of collagen and dying macrophages
• Direct cytotoxicity by particles
• Particle ingestion by macrophages results in activate and excessive free radical production = lipid peroxidation and cell injury
• Proinflamm cytokines and GF from macrophags and epithelial cells stimulate fibrblast proliferation and eventual scarring

Asbestosis

• Asbestos bodies consisting of fibres coated with an iron-containing protein are seen in fibrotic areas – especially in lung bases

Question 5

epi of pneumoconiosis

Answer 5

• Incidence increasing in developing countries
• Disability and mortality from asbestos will be increasing over next 20-30yrs

Question 6

sx of pneumoconiosis

Answer 6

Occupational history is important, there may be a long latency between disease exposure and expression.

Asymptomatic – found on routine CXR – simple coal or silica pneumoconiosis

Symptomatic

• Insidious onset of SOB and dry cough
• Black sputum – melanoptysis in coal worker’s
• Workers exposed to asbestos may develop pleuritic chest pain from asbestos pleurisy

Progressive massive fibrosis

• Progressive dyspnoea
• Fibrosis
• Cor pulmonale

Silicosis

• Progressive dyspnoea
• Increased incidence of TB

Question 7

signs of pneumoconiosis

Answer 7

May be normal

Decreased breath sounds in coalworker’s pneumoconiosis or silicosis.

In coal worker’s coexisting chronic bronchitis is common

End-inspiratory crepitations and clubbing in asbestosis.

Signs of a pleural effusion or right heart failure (cor pulmonale).

Question 8

Ix for pneumoconiosis

Answer 8

CXR

• Simple – modular mottling
• Complicated
  
  • Nodular opacities in the upper lobes
  • Micronodular shadowing
  • Diffuse military or nodular pattern in upper and mid-zones Eggshell calcification of hilar lymph nodes in silicosis
  • In asbestosis – bilateral lower zone reticulonodilar shadowing and pleural plaques, visible as white lines when calcified - most obvious on the diaphragmatic pleura or as ‘hollyleaf’ patterns.
• Progressive massive fibrosis
  
  • Bilateral, upper-mid zone fibrotic masses (1-10cm)
  • Develop from periphery to hilum

CT

• Fibrotic changes can be seen early

Bronchoscopy

• Visualise changes
• Allows for bronchalveolar lavage

Lung function test

• Restrictive ventilatory defect, impaired gas function