A mesothelioma in general is an aggressive malignant tumour (except for rare sub types such multicystic / cystic mesothelioma 8,9). The overwhelming majority arises from the pleura which this article will focus on. The reader is referred to a separate articles for discussion of
* peritoneal mesothelioma
* pericardial mesothelioma 10
* cystic / multicystic mesothelioma
Epidemiology
Mesotheliomas are uncommon entities and account for 5 - 28 % of all malignancies that involved the pleura1,7. There is a strong relationship between exposure to asbestos fibres (~ 10 % risk during lifetime) and this tumour ( ~ 40 - 80 % may have a history of asbestos exposure), and unlike other asbestos related lung disease, it doesn't appear to be dose dependant 1. Not all types of asbestos is strongly implicated, with crocidolite being the main mesothelioma causative fibre type. Not surprisingly, given the sources of asbestos exposure being predominantly mining, construction, lagging and machinery mechanics, 60 - 80% of cases are encountered in males, in general 20 to 35 years after exposure 1,5,6.
There has been no convincing evidence to suggest an association with smoking 6.
Clinical presentation
Typically patients present with dyspnoea and low posterior non-pleuritic chest pain. Pleural effusions are seen in the vast majority of patients at some stage during their disease. Up to 25% of patients have metastatic disease at the time of presentation if staged with FDG PET 5.
Pathology
There are three histological types of mesothelioma:
1. epithelial : ~ 60% *
2. mixed : 25%
3. sarcomatoid : 15%
The cytological and histological diagnosis can be difficult, with mesothelial hyperplasia and metastatic adenocarcinoma appearing similar. Specific markers are helpful including:
* calretinin
* epithelial membrane antigen
* cytokeratin
* mesothelin (elevated in 84 % of malignant mesothelioma versus < 2 % with other pleural disease 6)
* peritoneal mesothelioma
* pericardial mesothelioma 10
* cystic / multicystic mesothelioma
Epidemiology
Mesotheliomas are uncommon entities and account for 5 - 28 % of all malignancies that involved the pleura1,7. There is a strong relationship between exposure to asbestos fibres (~ 10 % risk during lifetime) and this tumour ( ~ 40 - 80 % may have a history of asbestos exposure), and unlike other asbestos related lung disease, it doesn't appear to be dose dependant 1. Not all types of asbestos is strongly implicated, with crocidolite being the main mesothelioma causative fibre type. Not surprisingly, given the sources of asbestos exposure being predominantly mining, construction, lagging and machinery mechanics, 60 - 80% of cases are encountered in males, in general 20 to 35 years after exposure 1,5,6.
There has been no convincing evidence to suggest an association with smoking 6.
Clinical presentation
Typically patients present with dyspnoea and low posterior non-pleuritic chest pain. Pleural effusions are seen in the vast majority of patients at some stage during their disease. Up to 25% of patients have metastatic disease at the time of presentation if staged with FDG PET 5.
Pathology
There are three histological types of mesothelioma:
1. epithelial : ~ 60% *
2. mixed : 25%
3. sarcomatoid : 15%
The cytological and histological diagnosis can be difficult, with mesothelial hyperplasia and metastatic adenocarcinoma appearing similar. Specific markers are helpful including:
* calretinin
* epithelial membrane antigen
* cytokeratin
* mesothelin (elevated in 84 % of malignant mesothelioma versus < 2 % with other pleural disease 6)
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