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Lung-nontumor

Infections

Legionella pneumophila / Legionnairesí disease


Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 20 September 2011, last major update September 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Clinical features
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● Initial public attention after epidemic in Philadelphia, Pennsylvania (US) convention of American Legion
● Caused by Legionella species, a short, gram-negative bacillus (Wikipedia)
● Retrospective review disclosed sporadic cases since early 1900ís
● Pontiac fever is caused by same bacteria, but without pneumonia, and often subclinical
● Hilar lymph nodes infected in 50% of cases at autopsy; 25% have spread to other organs
Causes: contaminated water in water-cooling tanks, drinking water conduits, air conditioning systems and other contained indoor water storage systems
● Immunosuppressed patients, especially organ transplant recipients, are especially vulnerable to severe disease
● Interaction with macrophages and dendritic cell subtypes appears to be important for resolution (Front Microbiol 2011;2:126)

Treatment
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● Erythromycin or other antibiotics, but high mortality in immunocompromised

Micro description
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● Extensive bronchopneumonia to lobar pneumonia with intra-alveolar neutrophils, macrophages, fibrin; often with leukocytoclastic neutrophilic infiltrate, small vessel vasculitis and necrosis

Micro images
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Gram stain


Silver stain

   
Immunofluorescence staining

Cytology images
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Impression smear from lung

Positive stains
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● Dieterle silver stain, monoclonal fluorescent reagent

Virtual slides
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Legionella pneumonia

EM images
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Legionella pneumonia

Additional References
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US Centers for Disease Control, Dail and Hammarís Pulmonary Pathology, 3rd edition, Kradin RL (ed), Diagnostic Pathology of Infectious Disease. Saunders; 2010

End of Lung-nontumor > Infections > Legionella pneumophila / Legionnairesí disease


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