Pneumoconiosis Flashcards
Definition
Fibrosing interstitial lung disease due to chronic exposure to mineral dusts
Types
- Simple: coalworkers or silicon worker lungs (symptom free)
- Complicated: Pneumoconiosis (progressive massive fibrosis) with low lung function
- Asbestosis: Pneumoconiosis caused by asbestos exposure (either white or blue coricodite asbestos)
Aetiology
Due to inhalation of particles of coal dust, silica or asbestos. In complicated
disease, nodules of particles surrounded by fibroblasts and dead macrophages develop. This is because in response to the lodging of a particle, there are several factors which promote nodule formation:
• Direct cytotoxicity to surrounding cells by the particle
• Macrophage ingestion of the particle, leading to free radical release and
neighboring tissue damage
• Cytokines/GF release leading to fibroblast proliferation and collagen
deposition
These all mostly occur in the lung bases in asbestosis
Risk
Occupaitonal exposure in coal mining, quarrying, iron working, steel foundries,
sandblasting, insulation industry, plumbers, ship builders.
Risk depends on extent of exposure, size and shape of particles, and predisposing
factors (smoking, TB)
Epidemiology
Incidence increasing in developing countries and wil for the next 20-30y due to latency period in onset with respect to exposure.
Presenting symptoms
Occupational history important. Long latency period.
Asymptomatic: picked up on CXR
Symptomatic: insidious onset dry cough and SOB. In coal, may have black
sputum (melanoptysis). Asbstos workers may develop pleuritic chest pain.
Signs on physical examination
Examination may be normal.
End inspiratory wheeze and clubbing in asbestosis
Decreased breath sounds in silicosis or coalworker
Signs of pleural effusion or heart failure
Investigations
CXR:
• Simple: micronodulat mottling is present
• Complicated: nodular opacities can be seen. In asbestosis, reticonodular
shadowing of the lung bases on the pleura above the diaphragm and
calcified leading to a holly leaf patter. In silicosis, eggshell calcification of
the hila.
CT scan: fibrotic changes seen earlier
Bronchoscopy: allows for broncholavage.
PFT: restrictive picture. Low FEV FVC, preserved or increased ratio.
Management plan
Avoidance of the exposure.
No specific treatment, steroid course trial. Oxygen for symptoms.
Patients are entitled for compensation
Complications
Progressive massive fibrosis, emphysema, cor pulmonale, pleural effusions, malignancy (mesothelioma – especially with blue asbestos, or carcinoma) end stage respiratory failure.
Prognosis
Does not recover, significant decrease in life span. Prognosis very poor if malignancy develops.
