Keywords:
Occupational / Environmental hazards, Education, Digital radiography, CT-High Resolution, Conventional radiography, Thorax, Respiratory system, Lung
Authors:
D. J. Martin, K. J. Litton, H. Adams; Cardiff/UK
DOI:
10.1594/esti2014/P-0108
Background
Pleural plaques are the commonest radiographic manifestation of,
and are virtually pathognomonic for,
asbestos exposure.
The formation of pleural plaques can occur after relatively limited exposure to asbestos,
which is in contrast to the greater exposure which is required to cause parenchymal lung disease.
The plaques are areas of fibrosis,
affecting mainly the parietal pleura, which are thought to form secondary to an inflammatory reaction to fibres that reach the pleura via the lymphatic system.
The time lag between exposure to asbestos and appearance of pleural plaques is approximately 20 to 30 years and they are therefore still widely encountered and are a relatively common finding on routine chest radiographs.
Pleural plaques vary in size,
number and location from patient to patient and this creates a wide spectrum of imaging findings.
There are however a number of characteristic appearances and knowledge of how these differ from other types of asbestos related pleural disease is vital for both the specialist and general radiologist.
In the majority of cases the diagnosis of pleural plaques can be achieved using a simple chest x-ray.
However CT can be used in more difficult cases and to increase the accuracy of the diagnosis.
There is also a potential role for other imaging techniques such as tomosynthesis.
This technique can confirm the diagnosis with potentially less radiation exposure than a CT scan of the thorax.
Medicolegal implications
In the United Kingdom there is currently disparity in the medico-legal implications of the presence of pleural plaques.
Prior to 2007 patients were able to pursue a civil claim for compensation.
However,
in October 2007 the House of Lords produced a ruling ending this right to claim.
Subsequent campaigns in Scotland resulted in the introduction of the Damages (Asbestos Related Conditions) Act 2009.
This act allowed civil claims for pleural plaques to recommence but only in Scotland.
The governments of England and Wales chose not to follow this example but the Northern Ireland Assembly did and introduced their own bill giving people the right to claim.
The claimant must however submit the claim within three years of the date they first became aware that they have an asbestos-related condition.
Therefore in England and Wales patients can only claimfpor compensation if they have proven asbestosis,
diffuse pleural thickening,
mesothelioma or lung cancer accompanied by asbestosis or bilateral diffuse pleural thickening.
The only caveat to that is if the person was working in Scotland or Northern Ireland during the time of the asbestos exposure they are still able to claim for compensation even if the eventual diagnosis was made whilst they were living in England or Wales.
Globally there is no consensus of opinion regarding the legal right to claim for the presence of pleural plaques.
The government of each individual country decides whether there is a case for compensation and indeed whether the state or the individual company who employed the patient at the time of exposure is liable if a claim is successful.