Tissue destruction in chronic pneumonitis.

A hitherto unrecognized, but apparently common, feature of chronic pneumonitis is tissue destruction. This feature may be as important as the proliferative component in formation of honeycomb lung. Fifty-two selected cases of active chronic pneumonitis were studied with hematoxylin-eosin stain, followed by bleach and Gordon and Sweets silver stain for reticulin. Thus, exactly the same cells and tissue could be studied with both stains. Pulmonary tissue destruction in regions of active chronic pneumonitis was indicated by (1) the presence of structureless eosinophilic material containing karyolytic nuclear remnants, (2) the presence of fragments of degenerated reticulin fibers within the air spaces, and (3) the phagocytosis of reticulin fiber fragments by macrophages.