Hematoxylin and eosin–stained sections reveal patchy lung parenchymal involvement by intra-alveolar loose fibrous plugs, intra-alveolar fibrin, reactive pneumocytes, and mild chronic interstitial inflammation (×2.5). (A) Higher magnification (×10) of loose fibrous plugs in alveolar spaces and indistinct granuloma. (B) Higher magnification (×10) of focus with chronic interstitial inflammation.