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| T1 pre-gad | T1 post-gad | T2 |
Diagnosis: Toxoplasmosis
Toxoplasma is an obligate intracellular parasite and is the most common cause of opportunistic CNS infection in immunocompromised patients. It often presents as multiple ring-enhancing lesions in the basal ganglia, cerebellar hemispheres or the grey-white junction of the cerebral hemispheres. Hemorrhage within the lesion may be seen after treatment. This patient was HIV + and had chronic meningitis of unknown etiology as well. The diagnosis of Toxoplasmosis was presumed and he was treated empirically. The increased white matter T2 signal was indeterminate. The fact that the rims of some of the lesions have bright signal on pre-gad T1s as well as on T2s suggests the presence of methemoglobin. The multiplicity, probable methemoglobin, ring enhancement and parenchymal location of these lesions favors toxoplasmosis over lymphoma. Lymphoma tends to be single and/or periventricular. Metastases, cysticercosis, and TB are other considerations. Related Cases
