The dense white encircling tumor mass is arising from the visceral pleura and is a mesothelioma. These are big bulky tumors that can fill the chest cavity. The risk factor for mesothelioma is asbestos exposure. However, mesothelioma is rare even in persons with asbestos exposure. Asbestosis more commonly predisposes to bronchogenic carcinomas, increasing the risk by a factor of five.
Smoking increases the risk for lung cancer by a factor of ten.
Thus, smokers with a history of asbestos exposure have a risk 50 fold greater likelihood of for developing lung cancer. This is the causative agent for asbestosis. This long, thin object is an asbestos fiber. Many houses and offices still contain building materials with asbestos, particularly insulation, so care must be taken when doing remodelling or reconstruction. Ingestion of these fibers by macrophages sets off a fibrogenic response via release of growth factors that promote collagen deposition by fibroblasts.