Image shows: Acute angled septate hyphae lying in necrotic debris and acute inflammatory exudates in lung.
FUNGAL INFECTIONS OF LUNG
- Aspergillosis is the most common fungal infection of the lung caused by Aspergillus fumigatus that grows best in cool, wet climate.
- The infection may result in allergic bronchopulmonary aspergillosis, aspergilloma and necrotising bronchitis.
- Grossly, pulmonary aspergillosis may occur within preexisting pulmonary cavities or in bronchiectasis as fungal ball.
- Microscopically, the fungus may appear as a tangled mass within the cavity.
- The organisms are identified by their characteristic morphology— thin septate hyphae with dichotomous branching at acute angles which stain positive for fungal stains such as PAS and silver impregnation technique.
- The wall of the cavity shows chronic inflammatory cells.
- Mucormycosis or phycomycosis is caused by Mucor and Rhizopus.
- The pulmonary lesions are especially common in patients of diabetic ketoacidosis.
- Mucor is distinguished by its broad, non-parallel, nonseptate hyphae which branch at n obtuse angle. Mucormycosis is more often angioinvasive, and disseminates; hence it is more destructive than aspergillosis.
- Candidiasis or moniliasis caused by Candida albicans is a normal commensal in oral cavity, gut and vagina but attains pathologic form in immunocompromised host.
- Angioinvasive growth of the organism may occur in the airways.
- It is caused by oval organism, Histoplasma capsulatum, by inhalation of infected dust or bird droppings.
- The condition may remain asymptomatic or may produce lesions similar to the Ghon’s complex.
- It is caused by Cryptococcus neoformans which is round yeast having a halo around it due to shrinkage in tissue sections. The infection occurs from infection by inhalation of pigeon droppings.
- The lesions in the body may range from a small parenchymal granuloma in the lung to cryptococcal meningitis.
- Coccidioidomycosis is caused by Coccidioides immitis which are spherical spores. The infection in human beings is acquired by close contact with infected dogs. The lesions consist of peripheral parenchymal granuloma in the lung.
- It is an uncommon condition caused by Blastomyces dermatitidis. The lesions result from inhalation of spores in the ground. Pathological features may present as Ghon’s complex-like lesion, as a pneumonic consolidation, and as multiple skin nodules.