Figure 4.

Microscopic features of the patient's lung middle and low lobes. Under low power microscope, the structure of middle (A,B) and lower lobes (C) were basically same (from where labeled “c and d” in Figure 2), The proliferative fibrous tissue thickened alveolar wall, resulted in the narrowness of alveolar space, even obstruction(hollow arrow). Some regions had fibrosis and consolidation, alveolar structural remodeling and many cystic fibrous gas cavity (*). NSIP-F or UIP was not easy to distinguish. In lower lobe, it is still visible the diffuse fiber hyperblastosis and residual alveolar structure in fibrotic tissues,indicating NSIP-F (D). ( H&E stain, Magnification:HE×40).