Bacterial Infections

Lobar pneumonia (with metastatic tumor)

The middle lobe shows diffuse consolidation (grey hepatization) of lobar pneumonia. The other lobes were not involved. The tumor is metastatic from a cancer of the mouth.

Lobar pneumonia

Alveoli are filled with PMNs, macrophages, and fibrinous exudate; alveolar walls are intact. This stage corresponds to grey hepatization. The preceding red hepatization was characterized by more RBCs in the alveoli.

Lobular pneumonia

Some organisms involve multiple lobules but not the whole lobe--lobular pneumonia. Legionnaire's disease is one of these. The alveoli of this lobule are filled with blood and PMNs. Adjacent lobules were much less involved.

Legionella bacilli

A Dieterle silver stain shows short rods, which are gram negative. A direct fluorescent antibody test can be used for typing.