Successful Treatment of Primary CNS Lymphoma Diagnosed by ²⁰¹Thallium-single Photon Emission Computed Tomography (²⁰¹Tl-SPECT) with Whole-brain Radiation Therapy in an AIDS Patient

Abstract

The patient, a 51-year-old male with a two year history of AIDS, was admitted to our hospital because of hemiparalysis and vomiting. The MRI study showed multiple lesions with ring-enhancement in the right basal brain area. Empirical therapy for toxoplasma encephalitis was started. After 64 days, the subsequent brain MRI showed deterioration. A ²⁰¹T1-SPECT study was performed and the findings were consistent with those of malignant lymphoma (ML). The patient was treated with 40 Gy of whole brain radiation, MRI showed partial response to this therapy, and clinical improvement was achieved. The definitive diagnosis of primary CNS lymphoma can be made only by brain biopsy, and many cases have been diagnosed at autopsy. The clinical and radiological findings of primary CNS lymphoma resemble toxoplasma encephalitis. An empirical therapyfor toxoplasma encephalitis is recommended to avoid brain biopsy in these cases. The use of ²⁰¹Tl-SPECT for the differential diagnosis of these diseases have been reported. Considering the poor prognosis of primary CNS lymphoma in AIDS, the application of ²⁰¹Tl-SPECT before empirical therapy for toxoplasma must be important for appropriate treatment.