Australian Society of CytologyCase of the Month
June 2002 - Answer and Discussion
Cryptococcus neoformans var. gattii
The bronchial brushings and washings show encapsulated organisms consistent with cryptococcus.
A bronchial biopsy, taken at the same time, shows cryptococcus in fragments of blood and fibrin.
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| Bronchial biopsy H&E stain 60x |
Bronchial biopsy PASD stain 60x |
Microbiology were able to culture and identify Cryptococcus neoformans var. gattii from the bronchial washings.
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| Indian ink preparation | Indian ink preparation |
Cryptococcus neoformans is a yeast with blastospores generally spherical 5 - 30 um in diameter, with a thick mucopolysaccharide capsule. The capsule stains with mucin stains such as PASD. They can be identified in wet preparations by negative staining with India ink. Cryptococcus neoformans lives naturally in soil contaminated with bird droppings, especially from pigeons and other seed-eating birds (Cryptococcus neoformans var. neoformans), or eucalyptus trees and decaying wood forming hollows in living trees(Cryptococcus neformans var. gattii).
The respiratory tract is thought to be the portal of entry for most infections. The most common infection identified is meningoencephalitis, followed by localised abscesses or granulomas in the lungs, brain, lymph nodes, skin or bones. Diffuse pulmonary infection is probably the most common type of infection but it is often asymptomatic and not detected. Cryptococcus has a low level of pathogenicity for normal adults. Unlike var. neoformans, which is mostly seen in immunocompromised patients, var. gattii infects immunocompetent hosts. Large mass lesions (cryptococcomas) in the lung and/or brain are the most common clinical presentation of var. gattii. The usual treatment is combination therapy with amphotericin B and 5-fluorocytosine or ketoconazole.
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