Cryptococcosis

Findings:
The axial T2 weighted images show multifocal signal abnormalities with mass effect in the bilateral basal ganglia. Numerous spotty foci of solid and nodular enhancement are present in the basal ganglia and cerebellum on the postcontrast T1 weighted images.

Differential Diagnosis:
cryptococcus, toxoplasmosis, less likely multifocal lymphoma/mets

Discussion:
Cryptococcosis is the most frequent CNS fungal infection, and is associated with a normal immune system in 50%. Cryptococcus is a ubiquitous organism that spreads hematogenously from the lungs. In immunocompetent individuals, the most common manifestation is meningitis which is usually not demonstrable by imaging. In immunocompromised individuals, the organisms and inflammatory response spreads along perivascular spaces in the basal ganglia (gelatinous pseudocysts- do not enhance). Multiple granulomas may then form, with variable enhancement. Abscess formation is rare. Occasionally, leptomeningeal enhancing nodules may be seen. 
 
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