The opacities consisted mainly of fine nodulation (14.2 %) in the upper and mid-zones of the lungs (Fig. 1), but one worker also had a large nodule 1 cm in diameter. Four cases had a diffuse haze that made recognition of the
lung parenchyma difficult. Fine calcification was also seen in two cases; one case showed fibrosis with obstructive
lung pattern (Fig. 2).