Which of the following is true regarding malignant mesothelioma?
A: Mesothelioma arise in the thorax from the visceral pleura only.
B: Sarcomatoid is the most common morphological type.
C: Correct Answer : The lifetime risk of developing mesothelioma in heavily exposed individuals is as high as 7-10%.
D: There is an increased risk of mesothelioma in asbestos workers who smoke.
Explanation:
The lifetime risk of developing mesothelioma in heavily exposed individuals is as high as 7-10%.
Malignant mesothelioma is a rare cancer of mesothelial cells, usually arising in the parietal or visceral pleura, although it also occurs, much less commonly, in the peritoneum and pericardium. It has assumed great importance because it is related to occupational exposure to asbestos in the air.
Approximately 50% of persons with this cancer have a history of exposure to asbestos. Those who work directly with asbestos (shipyard workers, miners, insulators) are at greatest risk, but malignant mesotheliomas have appeared in persons whose only exposure was living in proximity to an asbestos factory or being a relative of an asbestos worker.
The latent period for developing malignant mesothelioma is long, often 25 to 40 years after initial asbestos exposure, suggesting that multiple somatic genetic events are required for neoplastic conversion of a mesothe- lial cell. As stated earlier, the combination of cigarette smoking and asbestos exposure greatly increases the risk of lung carcinoma, but it does not increase the risk of developing malignant mesothelioma.
Morphology types: epitheliod (60%), sarcomatoid (20%) and mixed (20%). Asbestos bodies (and asbestos plaques) are found in increased numbers in the lungs of of patients with mesothelioma.