asbestos related lung disease Flashcards
definition of asbestosis
diffuse interstitial fibrosis of the lung as a consequence of exposure to asbestos fibres
Pleural abnormalities, which are also caused by the inhalation of asbestos fibres, include plaques that may or may not be calcified, diffuse pleural thickening, benign pleural effusions or rounded atelectasis
definition of mesothelioma
A tumour of mesothelial cells that usually occurs in the pleura, and rarely in the peritoneum or other organs.
aetiology of asbestosis
occupational history - inhalation of asbestos fibres
degree of asbestos exposure related to degree of pulmonary fibrosis
When asbestos fibres are inhaled, they deposit at alveolar duct bifurcations and cause an alveolar macrophage alveolitis
activated macrophages release cytokines, such as tumour necrosis factor and interleukin-1beta and oxidant species, which initiate a process of fibrosis
The initial interstitial fibrosis typically occurs in the lower lobes and may progress to extensive fibrosis and honeycombing. Peri-bronchial fibrosis with a cellular infiltrate may narrow the airway and cause reduced air flow.
aetiology of mesothelioma
associated with occupational exposure to asbestos but the relationship is complex
90% report previous exposure to asbestos, but only 20% of patients have pulmonary asbestosis
The latent period between exposure and development of the tumour may be up to 45yrs.
epidemuiology of asbestosis
In the UK, there were 517 asbestosis-related deaths (excluding mesothelioma) in 2017
There is a latency period of around 20 years from time of first exposure to asbestos to development of radiographical changes, so the diagnosis is typically seen in individuals who began working with asbestos prior to the 1980s and are now usually more than 50 years of age.
Family members of these workers were also exposed because of asbestos contamination of work clothes
use has decreased - risk is people working in places with previously installed asbestos
use in developing countries is increasing
epidemiology of mesothelioma
more common in men and white people,
60-90yrs
incidence increasing
sx of asbestosis
progressive dyspnoea
sx of mesothelioma
chest pain
dyspnoea,
weight loss
symptoms of met: bone pain, abdo pain (peritoneal malignant mesothelioma)
signs of asbestosis
clubbing
fine inspiratory crackles
effusion
pleural plaques
signs of mesothelioma
clubbing
recurrent pleural effusions
signs of met: lymphadenopathy, hepatomegaly, bone/abdo tenderness
path of asbestosis
causes pleural plaques, increased risk of bronchial adenocarcinoma and mesothelioma
Ix for asbestosis
CXR PA and lateral
- lower zone linear interstitial fibrosis; progressively involves the entire lung;
- pleural thickening
pul function tests
pul func tests for asbestosis
restrictive changes;
- reduced forced vital capacity (FVC), normal FEV1/FVC ratio, reduced slow vital capacity (SVC), reduced total lung capacity (TLC), reduced lung diffusion capacity testing (DLCO)
may have obstructive picture (especially if history of asbestos exposure and smoking)
- reduced FEV1, reduced FEV1/FVC ratio, increased residual volume (RV)/TLC ratio, reduced DLCO
Ix for mesothelioma
CXR/CT - pleural thickening/effuision
bloody pleural fluid
diagnosis made on histology, usually following thoracoscopy
often only made post-mortum
mx of asbestosis
- no smoking
- pul rehab
- oxygen therapy
- pleural decortication/lung transplant
complications of asbestosis
complications of mesothelioma
