Pneumoconiosis

Question 1

def

Answer 1

fibrosing interstitial lung disease caused by chronic inhalation of mineral dust

Question 2

what are the three types of pneumoconiosis

Answer 2

1 simple
-coalworker’s pneumoconiosis or silicosis
2 complicated
-pneumoconiosis (progressive massive fibrosis) which results in loss of lung function
3 asbestosis
-pneumoconiosis in which diffuse parenchymal lung fibrosis occurs as a result of prolonged exposure to asbestos

Question 3

aetiology

Answer 3

inhalation of particles of coal dust, silica, abestos

Question 4

what are the two types of asbestos

Answer 4

white asbestos

blue asbestos or crocidolite (more toxic)

Question 5

associations/risk factors

Answer 5

occupational exposure (coal mining, iron & steel foundries, insulation industry)
risk is dependent on extent of exposure, susceptibility, & co-factors such as smoking & TB

Question 6

epi

Answer 6

incidence increasing in developing countries

disability & mortality from asbestosis will increase

Question 7

history

Answer 7

occupational history is important
may be a delay between disease exposure & expression
ASYMPTOMATIC
-on routine CXR (simple coalworkers pneumonconiosis)
SYMPTOMATIC
-insidious onset of SOB & dry cough
-occasionally black sputum (melanoptysis) in coalworkers pneumoconiosis
-exposure to asbestos may result in pleuritic chest years later

Question 8

examination

Answer 8

may be normal
decreased breath sounds in coalworkers pneumoconiosis or silicosis
end inspiratory creps & clubbing in asbetosis
signs of pleural effusion or RHF

Question 9

pathogenesis

Answer 9

complicated disease
-large nodules in the lungs, which consist of dust particles (coal/silica) surrounded by laters of collagen & dying macrophages
mechanisms of damage:
1 direct cytotoxicity by particles
2 particle ingestion by macrophages results in activation & excessive free radical production causing lipid peroxidation & cell injury
3 proinflammatory cytokines & GFs from macrophages epithelial cells stimulate fibroblast proliferation and eventual scarring

Question 10

what is lipid peroxidation

Answer 10

oxidative degradation of lipids

Question 11

pathogenesis in asbestosis

Answer 11

asbestos bodies consisting of fibres coated with iron-containing protein are seen in fibrotic areas, especially at lung bases

Question 12

investigations

Answer 12

1 CXR
simple
-micronodular mottling
complicated
-nodular opacities in upper lobes, micronodular shadowing, eggshell calcification of hilar lymph nodes - characteristic of silicosis
-bilateral lower zone reticulonodular shadowing & pleural plaques, which are visible as white lines when calcified, often most obvious on the diaphragmatic pleura as 'holly leaf' patterns - characteristic of asbestosis 
2 CT scan
-for early fibrotic changes
3 bronchoscopy
-to visualise changes
4 LFTs
-restrictive ventilatory defect

Question 13

what is cor pulmonale

Answer 13

change in structure & function of RV caused by primary disorder of respiratory system
pulmonary HTN is common link between lung dysfunction & the heart

Question 14

what is caplans syndrome

Answer 14

complication of pneumoconiosis
also caused rheumatoid pneumoconiosis which is a combination of RA & pneumoconiosis which manifests as intrapulmonary nodules