Fig. 3

Histopathological findings from surgical lung biopsy specimens. a Hematoxylin and eosin (HE) staining of the right upper lung lobe S2 specimen revealed dense fibrosis with mononuclear cell infiltration and inorganic dust particles around the respiratory bronchioles, consistent with mixed dust pneumoconiosis. b Another field from the right upper lung lobe S2 specimen showed fibrously thickened interlobular septa and visceral pleura accompanied by fibroblastic foci (black arrowhead). It also identified some birefringent particles (black arrows) by polarized light microscopy (inset). c Elastica van Gieson staining of the right lower lung lobe S9 specimen showed extensive honeycomb changes and fibroblastic foci (black arrowheads) within the cystic wall. Scale bars indicate 200 μm