Finding a ring enhancing lesion in the CNS is most suggestive of toxoplasmosis (50%), lymphoma (30%), or other infectious agents.1 In order to make the diagnosis of toxoplasmosis with 90% probability of being correct, three criteria must be present: 1) positive serum titers to T. gondii (IgG) 2) no prophylaxis 3) typical radiographic appearance of multiple ring enhancing regions.2 If the patient receives treatment without resolution of symptoms or CNS findings, then lymphoma and other infections should be considered.