CNS Toxoplasmosis
- One of the most common opportunistic infections in the AIDS population caused by the obligate intracellular protozoan Toxoplasma gondii.
- Almost always caused by reactivation of a chronic infection, and usually becomes symptomatic when the CD4 count becomes < 100 μL.
- Clinical features: Subacute onset with focal neurologic abnormalities accompanied by headache, change in mental status and fever.
- Key Diagnostic Features: Favored locations: Basal ganglia and corticomedullary junction. CT: Iso- to hypodense lesions demonstrating peripheral enhancement. MR: Heterogenous mass lesion. Typically, central necrosis does not demonstrate restricted diffusion. Hemorrhage may be seen. MR spectroscopy demonstrates reduction in NAA/Cr with presence of lipid and lactate. Occasionally, an elevated Cho peak may be seen.
- DDx: Lymphoma, TB, primary brain tumor, metastatic brain tumor, tumefactive demyelinating lesion.
- Rx: Antitoxoplasmosis treatment
