An unusual case of central nervous system cryptococcosis

Opportunistic infections of the central nervous system (CNS) in immunocompromised patients often represent a diagnostic and therapeutic challenge due to the variety of possible infectious agents causing CNS disease. We report the case of a severely immunocompromised 43-year-old woman presenting with headache, confusion, abnormal CSF findings (cell count 237/mm3 with 50% eosinophils and elevated protein), multiple contrast enhancing lesions on CT and MRI in the basal ganglia, and serologic findings compatible with latent or reactivated toxoplasmosis with high IgA and IgG antibody titers against Toxoplasma gondii in whom a final diagnosis of CNS cryptococcosis was made. This case illustrates the considerable difficulties in the differential diagnosis of opportunistic CNS infection in the immunocompromised host. We conclude from our report that (1) the diagnosis of toxoplasma encephalitis should not be based on serological findings but rather be proven by either PCR, mouse inoculation or brain biopsy, (2) CNS cryptococcosis can be associated with marked CSF eosinophilia and multiple cryptococcomas, and (3) cryptococcomas can persist on CT and MRI despite successful antifungal treatment.