Fig. 5.
Characteristic lobar histological pattern. Per each lobe, the number in parentheses is the median infection-related lung injury score. All pulmonary sections were stained with hematoxylin and eosin. Right upper lobe (RUL): (A) (×100) a purulent mucus plug is within the bronchiole lumen, indicated by the filled arrow. The surrounding alveolar spaces are clear. (B) (×400) Polymorphonuclear cells are visible within the mucus plug. Right medium lobe (RML): (A) (×100) pneumonia is confluent, as the polymorphonuclear infiltrate is identifiable within three contiguous secondary lobes, separated by a septum (filled arrow). (B) (×400) Polymorphonuclear cells are seen on both sides of the interlobular septum. Right lower lobe (RLL): (A) (×100) the filled arrows indicate mucus plugs within the bronchiolar lumens, associated with bronchiolar wall alterations. (B) (×400) Polymorphonuclear infiltrate is visible within the bronchiolar wall, specifically, the emptied arrows indicate polymorphonuclear cells within the muscle fibers and the filled arrows show them extending toward the alveolar spaces. Left upper lobe (LUL): (A) (×100), extensive polymorphonuclear infiltrate is found within the alveolar spaces. (B) (×400) At higher magnification, the filled arrow shows a severe buildup of polymorphonuclear cells. Left lower lobe (LLL): (A) (×100) similar to the aforementioned pattern, a purulent mucus plug is seen within the bronchiolar lumen, associated with bronchiolar wall alterations. (B) (×400) The emptied arrows indicate polymorphonuclear cells within the muscle fibers of the bronchiolar wall. 0, no injury; 1, purulent mucous plugging; 2, bronchiolitis; 3, pneumonia; 4, confluent pneumonia; 5, abscessed pneumonia (cellular necrosis coexisting with disruption of cellular architecture)