Fig. 4

Histopathology of surgical lung biopsies of patient #3 (unclassifiable interstitial pneumonia, 60-years-old male, right S2). The specimen showed mixed fibrosing NSIP pattern and marked collapse with slight inflammatory cell infiltration. a, b Collapse with obliterative intraalveolar fibrosis and disrupted alveolar elastic fibers were observed in the square. c Fragmented elastic fibers of the alveolar walls were seen in a higher magnification of an area of a square of (b). Staining: (a) Hematoxylin and eosin stain, (b, c) Elastica van Gieson stein, Magnification: (a, b) 4×, (c) 10×