How do you distinguish cryptococcal meningitis from toxoplasmic encephalitis and CNS lymphoma in HIV-infected patients?
Patients with AIDS and a CD4 count of <200 cells/mm3 may be at risk for developing CNS OIs such as cryptococcal meningitis or toxoplasmosis, as well as CNS lymphoma; most infections occur in those with CD4 counts of <100 cells/mm3. Toxoplasmic encephalitis is rare in patients who are seronegative for Toxoplasma gondii (negative IgG antibody). CNS infection due to T. gondii and Cryptococcus spp. as well as CNS lymphoma may be relatively insidious in onset and associated with symptoms of fever, headache, and mental status changes. Focal neurological deficits and seizures are more likely to occur with toxoplasmic encephalitis and CNS lymphoma, although they sometimes occur in those with cryptococcal meningitis as well. The best diagnostic tests for a differential diagnosis of CNS disease are radiographic imaging of the CNS (with either a contrast-enhanced computerized tomographic [CT] scan or magnetic resonance imaging [MRI] scan) and lumbar puncture with cerebrospinal fluid (CSF) examina
