Figure 7a. Silicosis and progressive massive fibrosis in a 58-year-old man who worked for 30 years as a stoneworker. (a) Chest radiograph shows multiple small nodules and masses in both lungs, predominantly in the upper and middle zones, and eggshell calcifications (arrows) in the lung hilum and the mediastinum. (b) Axial thin-section CT scan (1.0-mm-thick section) obtained at the level of the aortic arch shows large symmetric bilateral opacities with irregular margins (arrows) indicative of progressive massive fibrosis, as well as numerous small nodules and septal thickening (arrowheads).