ABSTRACT
This chapter reviews the pulmonary and systemic pathology of Legionnaires' disease and other Legionella infections, concentrating on the gross and routine microscopic appearances of these infections that should suggest the diagnosis of legionellosis. Some patients with epidemic legionellosis may recover completely without long-term sequelae as documented by followup of survivors of the Philadelphia epidemic. Although some of these patients have persistent diffusion abnormalities on pulmonary function testing. Electron microscopic examination of lung tissue from cases of legionellosis confirms the cellular association of the organism. Numerous bacteria are found intracellularly in phagolysosomes and free in the cytosol of alveolar macrophages, and infrequently within neutrophils as well. All lung biopsies, regardless of type, should be cultured, and before fixation, sufficient numbers of imprints or smears should be made for Gram and direct fluorescent antibody staining, since these procedures have a better yield on unprocessed tissue.
