Figure 1: Here we present an HIV patient with low CD4 count who was not taking HAART around the time of imaging. These images demonstrate at least two T1 hypointense (top row left), FLAIR hyperintense (top row right) lesions centered within the left parietal cortex and left basal ganglia. Both lesions demonstrate punctate, central restricted diffusion (middle row). The lesion in the left parietal cortex has a rim of thick enhancement (bottom row left) and there is minimal associated susceptibility artifact (bottom row right) likely reflecting microhemorrhage.
- Most commonly caused by Candida albicans, though glabrata and parasilosis are also common
- CNS infection almost always caused by hematogenous spread with disseminated systemic infection
- Small, round to oval, thin-walled, yeast like fungi that reproduce by budding or fusion
- Pseudohyphae predominate, but occasionally true hyphae are also seen.
- Variable but generally include insidious-onset lethargy and altered mental status
- Age and gender
- Risk factors
- Treatment for bacterial sepsis, IV hyperalimentation, HIV with low CD4, immunosuppression, hematologic malignancy, and premature birth
- Most common findings are numerous microabscesses (<3mm) occurring at the corticomedullary junction, basal ganglia, or cerebellum
- Often demonstrate enhancement and less often demonstrate hemorrhage or infarction
- Meningitis is a less common presentation
- Modality specific
- hyper-, iso- or hypointense
- Hypointensity seen in the setting of hemorrhage
- Small ring-enhancing lesions
- Imaging Recommendations
- Standard protocol MR (including DWI) with intravenous contrast
- The most common presentation of numerous microabscesses is most difficult to distinguish from metastatic disease and other fungal processes. Clinical history with appropriate risk factors often provide the most help when narrowing the differential.
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Sean Dodson, MD
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Lin DJ, et al. Neurocandidiasis: A Case Report and Consideration of the Causes of Restricted Diffusion. J Raiol Case Rep. 2013; 7(5):1-5.
Rabelo NN, et al. Differential Diagnosis between Neoplastic and Non-Neoplastic Brain Lesions in Radiology. Arq Bras Neurocir. 2016. Doi: 10.1055/s-0035-1570362.
Shih RY, et al. Bacterial, Fungal, and Parasitic Infections of the Central Nervous System: Radiologic-Pathologic Correlation and Historical Perspectives: From the Radiologic Pathology Archives. Radiographics. 2015; 35(4):1141-69.
Starkey J, et al. MRI of CNS Fungal Infections: Review of Aspergillosis to Histoplasmosis and Everything in Between. Clin Neuroradiol. 2014; 24(3):217-30.
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