Fungal infections of the CNS
- Lesion
Fungi reach the brain mostly in people with weak immunity, causing chronic meningitis, abscesses or blocked and bleeding vessels.
What it is
Fungal infection of the CNS usually follows spread through the blood in immunocompromised patients, or direct extension from the sinuses in poorly controlled diabetes. Three patterns occur, often together: chronic meningitis, vasculitis with infarcts, and parenchymal abscesses or granulomas. Cryptococcus is the classic cause of meningitis in AIDS; Mucor and Aspergillus invade vessel walls and cause hemorrhagic infarcts. Endemic fungi such as Histoplasma and Coccidioides involve the brain after lung infection.
Structure
- Cryptococcal meningitis: gelatinous exudate, organisms in the subarachnoid space and perivascular spaces with sparse inflammation in advanced AIDS.
- Angioinvasive fungi: thrombosed arteries packed with hyphae and hemorrhagic necrosis of the territory supplied.
Fungi that infect the CNS
| Fungus | Host | Pattern | Morphology |
|---|---|---|---|
| Cryptococcus | AIDS, transplant; C. gattii in healthy hosts | Chronic meningitis, perivascular cysts | Budding yeast with a thick capsule |
| Candida | ICU, neutropenia | Microabscesses, granulomas | Yeasts and pseudohyphae |
| Mucorales | Diabetic ketoacidosis, iron overload, neutropenia | Spread from sinus and orbit, vascular invasion | Broad hyphae without septa, right-angle branches |
| Aspergillus | Neutropenia, transplant | Septic infarcts, hemorrhage | Narrow septate hyphae, acute-angle branches |
| Histoplasma, Coccidioides, Blastomyces | Endemic areas, often with immunosuppression | Meningitis, granulomas | Small intracellular yeasts, spherules or broad-based buds |
Markers
- Mucicarmine (cryptococcal capsule)
- Grocott methenamine silver
- PAS
- Cryptococcal antigen
Clinical notes
- Cryptococcal meningitis gives headache and confusion with very high opening pressure; repeated CSF drainage is part of care.
- Histoplasmosis and paracoccidioidomycosis are endemic in parts of Colombia and Latin America.
Test yourself
Think of the answer, then tap the question to see it.
Which stain highlights the capsule of Cryptococcus in tissue?
Mucicarmine, which stains the polysaccharide capsule red.
How do Mucor hyphae differ from Aspergillus hyphae?
Mucor hyphae are broad, ribbon-like, without septa and branch at right angles; Aspergillus hyphae are narrow, septate and branch at acute angles.
In which metabolic state does rhino-orbito-cerebral mucormycosis classically occur?
Diabetic ketoacidosis.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: About Cryptococcosis | Cryptococcosis | CDC (Centers for Disease Control and Prevention, 2026).
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Representative model, for educational purposes only.