Mesothelioma lung tumour caused by asbestos. Coloured axial computed tomography (CT) scan through the chest and lungs of a 68-year-old female patient with a mesothelioma tumour of the right lung. In this view from below, the spine is at lower centre, and the sternum at upper centre. This type of tumour arises from the pleura, the membrane encasing the lungs, and in this case there is significant thickening of the pleura surrounding the right lung. Mesothelioma is usually associated with exposure to asbestos. Although it can cause a cough and chest pain, in many cases the condition is symptomless. This delays diagnosis and therefore treatment.