There are various fungi that may cause meningitis. The manifestations vary by causative organism and host immune status. Some organisms are more common in certain geographical locations. Patients may present acutely with headache and encephalopathy or may have a much more indolent course.
Cryptococcal meningitis:
Synonyms:
Cryptococcosis (Cryptococcus neoformans)
Diagnosis:
Clinical findings plus isolation of the cryptococcus neoformans organism or identification of cryptococcal antigen
Findings on investigation:
CSF analysis:
- Cryptococcus antigen: positive. 95% sensitive
- India Ink stain: positive, 50% sensitive, white capsule, pale nucleus
- WCC: high opening pressure, lymphocytosis in low counts, reduced glucose but may be normal, elevated protein,
Blood, in disseminated infection:
- Blood cryptococcal antigen: positive, false positive in patients with positive rheumatoid factor RF
- Isolator cultures: positive
- Fungal culture:
- For 6 weeks at 37 degrees
CT:
- Hypodensity suggest infarcts
- Hydrocephalus
MRI:
- Findings of infarcts may occur
- Hydrocephalus
- T2: Basal ganglia hyperintense cysts (gelatinous pseudocysts), T1 +GAD: mildly enhancing
- Gyral enhancement
MRA:
- Findings of vasculitis may occur
Angiography:
- Findings of vasculitis may occur
Other tests:
- CXR: pulmonary infiltrates +/- lymphadenopathy may occur. May be negative in pulmonary disease. Bronchoalveolar lavage (BAL) culture or cryptococcal antigen positive
Pathology, Biopsy:
- Immunocompetent patients: Focal granuloma, macrophages, microglia
- Immunodeficient patient: no or minimal inflammation
- H&E: clear capsule, blue nucleus, involves Virchow-Robin spaces. More organisms in immunodeficient patients.
- Meninges: GMS stain, Cryptococcus organisms
- India ink CSF: white capsule, pale nucleus
Cryptococal meningitis treatment:
- Amphotericin B
- Fluconazole