A. Lung showing extensive interstitial and alveolar fibrosis.
    Note the increased interstitial cellularity with numerous fibroblasts.
B. Patchy areas of alveolar septal thickening and prominent hyaline membranes.
C. Higher magnification showing typical dense laminated hyaline membranes.
D. Alveolar septum showing prominent type II pneumocyte proliferation.
E. Abundant polymorphonuclear leukocytes fill alveolar spaces with focal destruction of alveolar septa.
F. Higher power magnification showing the antraalveolar exudate
composed mainly of polymorphonuclear leukocytes, red blood cells, and fibrin.