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Case 3: A 36-Year-Old with Headache, Fever, and a Seizure

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C Based on the clinical presentation and the radiographic findings, the most likely diagnosis is primary central nervous system lymphoma. Radiation therapy should emergently be arranged.

This answer is incorrect. Although a diagnosis of primary central nervous system lymphoma is possible, the diagnosis of Toxoplasma encephalitis is more likely considering the multiple mass lesions, the positive Toxoplasma antibody test, and the fact that the patient had not been taking Toxoplasma prophylaxis. In such a setting, most experts would recommend empiric therapy for Toxoplasma encephalitis.

A The presence of more than one mass lesion rules out central nervous system lymphoma.
B Approximately 10% of primary central nervous system lymphomas in patients with AIDS are associated with Epstein-Barr virus (EBV). Performing cerebrospinal fluid (CSF) PCR does not usually provide useful information.
D Based on the clinical and radiographic findings, the most likely diagnosis is Toxoplasma encephalitis. Empiric therapy with pyrimethamine (Daraprim) plus sulfadiazine plus leucovorin should be started.

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