Cryptococcosis
Cryptococcus
neoformans
Epidemiology and Etiology:
- Usually an
opportunistic infection in immune compromised – corticosteroids is a
major risk factor:
- AIDS
- Leukemia
- Lymphoma
- SLE
- Hodgkin lymphoma
- Sarcoidosis
- Transplant recipients
- Normal habitats:
- Soil
- Bird (pigeon) droppings
- Infection through
inhalation
- Virulence factors:
- Polysaccharide
capsule (inhibits phagocytosis)
- Phenotypic switching
of capsule polysaccharide
- Laccase (catalyzes formation of a melaninlike pigment – antioxidant?)
- Consumes epinephrine,
avoids epinephrine oxidative system present in the nervous system
- Serine proteinase
Common sites:
- Meningoencephalitis
- Meninges
- Cortical gray
matter
- Basal nuclei
- Lung (but usually
asymptomatic)
- Disseminated
- Skin
- Liver
- Spleen
- Adrenals
- Bones
Gross features:
- Pulmonary granuloma similar to coin lesions caused by Histoplasma
Histologic features:
- encapsulated yeast
form only
- 5-10 microns
- thick gelatinous capsule (important)
- intense
red on PAS and mucicarmine
stains
- granulomatous reaction in nonimmunosuppressed
patients or those with protracted disease
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- latent infections
with granuloma formation may reactivate in immunosuppressed
References: