Occupational Lung Diseases

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Silicosis & CWP - Rock Dust Perils

  • Pneumoconioses from inhaling crystalline silica (Silicosis) or coal dust (CWP).
    • Pathogenesis: Dust → macrophage activation → inflammation → fibrosis.
  • Key Features & Occupations:
    • Silicosis: Mining, sandblasting, stone cutting.
      • ↑ TB risk (silicotuberculosis), lung cancer.
    • CWP: Coal mining. "Black Lung Disease".
  • Clinical Presentation:
    • Often asymptomatic initially; progresses to dyspnea, cough.
    • PMF (Progressive Massive Fibrosis): Opacities >1 cm, severe impairment.
  • Radiology:
    • Small, rounded opacities, predominantly upper lung zones. 📌 Mnemonic for upper lobe: "STAB C" (Silicosis, TB, Ankylosing Spondylitis, Berylliosis, CWP).

    ⭐ Silicosis shows 'egg-shell' calcification of hilar lymph nodes and predominantly affects upper lung zones.

  • Shared Complication: Caplan's syndrome (pneumoconiosis + rheumatoid arthritis).
  • Management: No cure; supportive, remove exposure, monitor.

Silicosis Chest X-ray with egg-shell calcification

Asbestosis & Berylliosis - Fiber & Metal Ills

  • Asbestosis
    • Source: Asbestos fiber inhalation (shipbuilding, insulation). Amphibole fibers → mesothelioma.
    • Patho: Diffuse interstitial fibrosis (mainly lower lobes). Pleural plaques (parietal, calcified "holly leaf").
    • C/F: Progressive dyspnea, dry cough, clubbing. Latency: 15-20+ years.
    • Dx: CXR/HRCT (bibasilar opacities), PFTs (restrictive), asbestos bodies (sputum/BAL/biopsy).

    ⭐ Asbestosis primarily affects lower lung lobes and is strongly linked to mesothelioma and bronchogenic carcinoma (synergistic with smoking, risk ↑ ~50x). HRCT chest asbestosis bibasilar fibrosis pleural plaques

  • Berylliosis (Chronic Beryllium Disease - CBD)
    • Source: Beryllium (aerospace, electronics, dental).
    • Patho: Type IV hypersensitivity → non-caseating granulomas (sarcoid-like).
    • C/F: Dyspnea, cough, fatigue, hilar lymphadenopathy.
    • Dx: +BeLPT (blood/BAL), biopsy (granulomas). CXR/HRCT: nodules, hilar adenopathy, fibrosis (upper lobe predilection).
    • Rx: Corticosteroids.

HP & Occupational Asthma - Allergen Alert

  • Hypersensitivity Pneumonitis (HP): Immune-mediated lung disease (Type III/IV hypersensitivity) from inhaled organic antigens (e.g., molds, bird proteins).
    • Acute: Fever, cough, dyspnea 4-8 hrs post-exposure.
    • Chronic: Progressive fibrosis, irreversible.
    • HRCT: Ground-glass opacities, centrilobular nodules (acute); honeycombing (chronic).

    ⭐ Farmer's Lung (HP) from thermophilic actinomycetes (e.g., Saccharopolyspora rectivirgula); recurrent flu-like symptoms hours after exposure.

  • Occupational Asthma: Variable airflow obstruction due to workplace agents.
    • Sensitizer-induced (latency) or Irritant-induced (immediate).
    • Symptoms (wheeze, dyspnea) improve away from work.
    • Diagnosis: PEFR variability (>20%), specific bronchial provocation tests.
  • Management: Exposure cessation is key; corticosteroids.

HRCT: Nonfibrotic Hypersensitivity Pneumonitis Findings

  • Prevention: Key Measures
    • Primary: Engineering controls (e.g., ventilation, wet methods), substitution of hazardous agents, appropriate PPE (respirators, masks).
    • Secondary: Pre-placement & periodic health surveillance (spirometry, chest X-ray), worker education.
    • Tertiary: Early diagnosis, treatment, rehabilitation, job retraining.
  • Medico-Legal & Compensation (India):
    • Factories Act, 1948: Safe work environment, disease notification.
    • Workmen's Compensation Act, 1923 (Employees Comp Act): Compensation.
    • Employees' State Insurance (ESI) Act, 1948: Medical care & disability benefits.
    • Mines Act, 1952: Mine safety regulations.
    • Certification: Medical boards assess disability for compensation.

⭐ The ILO Classification of Radiographs of Pneumoconioses is crucial for standardized assessment and medico-legal purposes in occupational lung diseases.

High‑Yield Points - ⚡ Biggest Takeaways

  • Silicosis: Upper lobe opacities, eggshell calcification of hilar nodes, increased TB risk.
  • CWP: Upper lobe nodules, risk of PMF; Caplan syndrome (RA + pneumoconiosis).
  • Asbestosis: Lower lobe fibrosis, pleural plaques (commonest), ↑ risk of mesothelioma & bronchogenic carcinoma.
  • Byssinosis: Cotton dust; "Monday fever" (chest tightness), symptoms improve through week.
  • Berylliosis: Non-caseating granulomas (mimics sarcoidosis); aerospace/electronics exposure.
  • Hypersensitivity Pneumonitis: (e.g., Farmer's Lung) Immune reaction to organic antigens (moldy hay).

Practice Questions: Occupational Lung Diseases

Test your understanding with these related questions

A disease associated with prolonged exposure to silica dust during glass production, characterized by classic X-ray findings of calcified lymph nodes and pleural involvement, is most likely what disease?

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Flashcards: Occupational Lung Diseases

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Chronic bronchitis presents with _____ due to excessive mucus production and late-onset dyspnea

TAP TO REVEAL ANSWER

Chronic bronchitis presents with _____ due to excessive mucus production and late-onset dyspnea

productive cough

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