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).