Occupational Lung Diseases

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.

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).

• 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.

Prevention & Medico-Legal - Lung Shield Laws

• 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).