A 75-year-old man who had worked in a shipyard for 25 years dies of a thoracic tumor. Autopsy reveals a pleural tumor that encases the lung. Interstitial pulmonary fibrosis and multiple pleural plaques are noted. Numerous, brown, beaded ferruginous bodies are also found in the lungs as shown in the image. Which of the following agents is most likely associated with the pathogenesis of the cancer in this patient?
Answer :A Asbestos
Occupational exposure to asbestos poses a risk for the development of a pleural tumor termed malignant mesothelioma.
Malignant disease may become evident 20 to 30 years following exposure. The inhalation of asbestos fibers also causes interstitial fibrosis of the lungs and pleural plaques consisting of dense connective tissue. Asbestos fibers coated with protein and iron are termed asbestos (ferruginous) bodies.
The other choices do not produce ferruginous bodies or cause mesothelioma.