martedì 18 settembre 2007

Cryptococcal meningitis


There is nodular thickening and T2-weighted hyperintensity of the callosal splenium with associated diffusion restriction. There is subtle leptomeningeal enhancement.

Differential Diagnosis:
- Embolic infarcts
- Abscess / multifocal infection
- Marchiafava-Bignami syndrome
- Diffuse axonal injury
- Lymphoma

Diagnosis: Cryptococcal meningitis

Key points

Cryptococcus neoformans is a ubiquitous yeast that grows abundantly in soil containing bird (especially pigeon) droppings. Disseminated infection occurs mainly in the immunocompromised, with the lungs and central nervous system most commonly affected. Cryptococcosis risk factors include; AIDS, steroid therapy, immunosuppression induced after organ transplantation, lymphoproliferative disorders, diabetes, tuberculosis, and sarcoidosis. Approximately 30-50% of patients with cryptococcal meningitis, however, show no evidence of immunosuppression (as in this case).

Nonspecific symptoms include:
- Fever
- Headache
- Changes in level of consciousness (somnolence, confusion, stupor or coma)
- Dizziness
- Visual disturbances
- Seizures

Diagnosis relies on CSF Indian ink preparation, culture, and antigen titers.

Radiologic overview of the diagnosis

Manifests as meningoencephalitis with gyral enhancement and intraparechymal lesions. Intraparechymal lesions include non-enhancing gelatinous pseudocysts (often in the basal ganglia) and enhancing cryptococcomas. Cerebral infarction can result from chronic infection. Brain lesions may worsen with Amphoterician-B treatment, causing concern for treatment failure. Hydrocephalus and diffuse atrophy can also be seen, yet could be related to an underlying disease process such a HIV.

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