Silicosis

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1- Definition & Types

2- Causes (Aetiology)

3- Pathophysiology

4- Clinical Features & Examination

5- Investigations

6- Management

7- Complications

8- Core Concepts

Definition & Types

Silicosis is a progressive fibrotic lung disease caused by inhaling crystalline silica dust (usually quartz), particularly in occupations involving cutting, grinding, or polishing stone.

Types:

  • Chronic/classic silicosis:

    • Most common

    • Appears after 10–20 years of exposure

    • May initially be asymptomatic

  • Accelerated silicosis:

    • 5–10 years of exposure

    • More aggressive course

  • Acute silicosis (silicoproteinosis):

    • Within 1 year of intense exposure

    • Resembles alveolar proteinosis

© image from Wikimedia Commons

Causes (Aetiology)

Occupational exposure in:

  • Mining and quarrying

  • Stone dressing

  • Pottery work

  • Metal grinding

  • Boiler scaling

  • Sandblasting

Pathophysiology

  1. Inhaled silica particles are taken up by alveolar macrophages

  2. These cause inflammatory and fibrotic responses

  3. Leads to nodular interstitial fibrosis

  4. Can progress to Progressive Massive Fibrosis (PMF) even after exposure stops

  5. Increased risk of:

    • Tuberculosis (silicotuberculosis)

    • Lung cancer

    • COPD

Clinical Features & Examination

TypeSymptoms
Early/chronic silicosisOften asymptomatic despite radiographic changes
PMFCough, progressive dyspnoea, weight loss
Acute silicosisRapid onset breathlessness, hypoxaemia, chest tightness
Physical examMay reveal fine crackles; clubbing is rare unless fibrotic

Investigations

Imaging:

  • CXR:

    • Small, rounded nodules (3–5 mm), predominantly in upper/mid zones

    • May show ‘egg-shell’ calcification of hilar nodes (non-specific but suggestive)

  • HRCT:

    • Better shows nodular opacities, their conglomeration, and posterior bias (Fig 17.62)

– Lung Function:

  • Restrictive pattern

  • ↓ DLCO in advanced disease

– Other:

  • Tuberculosis testing is essential due to increased TB risk

  • Autoimmune screen if connective tissue disease suspected

© image from Wikimedia Commons

Management

No cure — focus is on prevention, monitoring, and symptom control

  • Eliminate exposure immediately — mandatory

  • Monitor for TB: regular screening

  • Symptomatic treatment:

    • Inhaled bronchodilators if airflow obstruction

    • Oxygen therapy for hypoxaemia

    • Pulmonary rehab

  • Vaccination: influenza and pneumococcus

  • Avoid immunosuppressants unless autoimmune overlap (e.g. Caplan’s)

Complications

  • Progressive massive fibrosis (PMF)

  • Silicotuberculosis

  • Lung cancer

  • COPD/emphysema

  • Possible association with renal and connective tissue diseases

Core Concepts

  • Silica is highly fibrogenic → disease can progress after exposure ends

  • Upper lobe nodules + egg-shell calcification = Think silicosis

  • Always exclude TB in any symptomatic patient with silicosis

  • Prevention is key: once fibrotic damage is done, it’s irreversible

  • Acute silicosis = medical emergency, mimics alveolar proteinosis

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