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Pathology of common pulmonary fungal infections
1Department of Pathology, University of Texas Medical Branch, Galveston 77555-0747.
Abstract:
The incidence of fungal pneumonias has increased dramatically since the 1960s, particularly in immunocompromised patients. Fungal infections may be divided into endemic and opportunistic varieties. In general, the truly pathogenic (endemic) fungi infect healthy individuals, and opportunistic fungi usually infect only immunocompromised hosts. Almost all common fungal infections are acquired by inhalation of contaminated soil, resulting in pulmonary infections. Once in the lungs, the fungi elicit tissue responses ranging from acute exudative reactions to granulomatous reactions. The pulmonary lesions may resolve, progress to a prolonged chronic course, or disseminate to other organs, resulting in systemic infections. The diagnosis of fungal infection depends on the demonstration of the organisms by culture or histology; serologic tests may confirm the diagnosis. Fungi in tissues can be identified by hematoxylin and eosin stains, but special stains such as Gomori's methenamine silver and periodic acid-Schiff reagent are often required for diagnosis.
Insights
Fungal pneumonias have increased, especially in immunocompromised patients. Diagnosis relies on identifying fungi via culture, histology, or serology, often needing special stains.
Area of Science:
- Mycology
- Pulmonology
- Infectious Diseases
Background:
- Fungal pneumonias show increased incidence since the 1960s, particularly in immunocompromised individuals.
- Fungal infections are categorized as endemic (pathogenic in healthy hosts) or opportunistic (affecting immunocompromised hosts).
- Pulmonary fungal infections are primarily acquired through inhalation of contaminated soil.
Purpose of the Study:
- To review the epidemiology, pathogenesis, and diagnostic methods for fungal pneumonias.
- To highlight the diagnostic challenges and techniques for identifying fungal pathogens in pulmonary tissues.
Main Methods:
- Review of literature on fungal pneumonia incidence, classification, and acquisition.
- Discussion of host responses to fungal lung infections, including inflammatory reactions.
- Overview of diagnostic approaches, including microscopy, special stains, and serology.
Main Results:
- Fungal infections present diverse tissue responses, from acute inflammation to granulomatous reactions.
- Pulmonary lesions can resolve, become chronic, or disseminate systemically.
- Identification of fungi in tissues often requires special stains like Gomori's methenamine silver and PAS.
Conclusions:
- Accurate diagnosis of fungal pneumonia is crucial, especially in at-risk populations.
- Histopathological examination with special stains is vital for definitive fungal identification.
- Understanding the spectrum of fungal infections aids in timely diagnosis and management.