INTRODUCTION Granulomatous inflammation is a distinctive ...

Neuroimaging
The imaging findings related to cryptococcal involvement of the CNS are quite variable, and with
regard to cryptococcal meningitis, most cases are negative. The most common finding of
cryptococcal infection is a communicating or noncommunicating hydrocephalus (Takasu et al.,
1991). Hydrocephalus is more commonly seen in non-AIDS patients in 25% of cases compared
with 9% in the immunocompromised population. The lower percentage in the
immunocompromised population may be related to an inability to initiate an inflammatory
response to the meningoencephalitis or the formation of adhesions within the basal cisterns
(Witeman et al., 1996), Leptomeningeal enhancement is an uncommon finding.
Hypoattenuating nonenhancing lesions within the basal ganglia may be present on CT scan and
represent dilated Virchow-Robin spaces. These areas are isointense to cerebrospinal fluid without
surrounding edema on MR imaging (figure 8). These spaces may become voluminous as the
yeasts, which are present in these areas, produce mucoid material that distends these areas. These
gelatinous pseudocysts pathologically do not show evidence of an immune response and
occasionally may extend into the periventricular region. The presence of gelatinous pseudocysts
suggests an immunocompromised state (Zheng et al., 1996). Other patterns of involvement include
the miliary form or the presence of granuloma (cryptococcoma), which may be of low or high
attenuation on CT scan. On MR imaging, these lesions are typically hypointense on Tl-weighted
images and hyperintense on T2-weighted images (Figure 9) (Andreula et al., 1993).
Immunocompetent patients more often present with cryptococcomas (Ostrow et al., 1994). MR
imaging is more sensitive than CT scan in the depiction of these lesions. These lesions may show
enhancement after the administration of contrast material. In some instances, the administration
of double dose contrast material may show these abnormalities better (Andreula et al., 1993).
Figure 8. Cryptococcus, T1-weighted MRI
demonstrates dilated perivascular spaces in the bilateral
basal ganglia (Metwally, 2006-9)
Figure 9. Cryptococcus, T2-weighted axial MRI
demonstrates hyperintense cryptococcomas in the