A 48-year-old man with AIDS is admitted to the hospital with a fever of 38.7degC (103degF), persistent cough, and diarrhea. His CD4 cell count is less than 500/mL. The patient is started on broad-spectrum antibiotics. He has also experienced a recent decline in cognitive function. He is at increased risk of developing which of the following CNS neoplasms?

Lymphomas may arise as a primary B-cell lesion in the brain in a manner analogous to its occurrence in the stomach, small bowel, or testis, but the overwhelming majority of lymphomas are metastatic to the brain from other sites. Primary lymphoma of the brain often originates deep in the cerebral hemispheres, commonly in bilateral periventricular positions. A mixture of small and large lymphocytes is angiocentric. Lymphomas often arise in the context of immunosuppression and in patients with AIDS. In some instances, they have been linked etiologically to infection with EBV. AIDS does not give rise to tumors of neural origin (choices A, B, D, and E).Diagnosis: Lymphoma