MEDizzy - A 39-year-old HIV-positive man has received no

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Central Nervous System (II)

A 39-year-old HIV-positive man has received no antiretroviral therapy. He has had left-sided weakness for the past month and experienced a generalized seizure a day ago. On physical examination, he is afebrile. CT scan of the head shows no intracranial hemorrhage, but there is a midline shift. MRI of the brain shows a 4-cm mass in the region of the putamen near the right internal capsule, a 3-cm mass in the right centrum semiovale, and a 1-cm mass near the splenium of the corpus callosum. These masses are circumscribed and solid. CSF from a lumbar puncture shows an elevated protein concentration and a normal glucose level. Cytologic examination shows large cells with large nuclei and scant cytoplasm that mark with CD19, but not with GFAP or cytokeratin. What is the most likely diagnosis?

ExplanationNon-Hodgkin lymphomas, including large B-cell lymphomas, are uncommon in the brain, but they may be seen in immunocompromised patients, particularly patients with AIDS. They tend to be multifocal. Cytomegalovirus infection is common in AIDS, but it is unlikely to produce mass lesions. A glioblastoma can be a large infiltrative and destructive mass, but the cells are typically glial fibrillary acidic protein (GFAP) positive and CD19 negative. Kaposi sarcoma can occur in association with HIV infection, but CNS involvement is rare, and the cells are CD34 positive.