A 52-year-old man is brought to the emergency department because of headaches, vertigo, and changes to his personality over the past few weeks. He was diagnosed with HIV 14 years ago and was started on antiretroviral therapy at that time. Medical records from one month ago indicate that he followed his medication schedule inconsistently. Since then, he has been regularly taking his antiretroviral medications and trimethoprim/sulfamethoxazole. His vital signs are within normal limits. Neurological examination shows ataxia and apathy. Mini-Mental State Examination score is 15/30. An MRI of the brain with contrast shows a solitary ring-enhancing lesion involving the corpus callosum and measuring 4.5 cm in diameter. A lumbar puncture with subsequent cerebrospinal fluid analysis shows slight pleocytosis, and PCR is positive for Epstein-Barr virus DNA. Tissue biopsy from the frontal lobe lesions would likely predominantly show an abnormal population of which of the following cells?

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Quizplus · Accepted Answer

Eductional Objective: Primary CNS lymphoma is typically composed of B-lymphocytes that is most commonly associated with immunosuppression (e.g., due to HIV infection) and EBV infection. Its incidence is much higher in patients with HIV/AIDS compared to the general population, and it typically occurs in patients with a CD4 count < 100/mm3. Primary CNS lymphoma usually manifests with focal neurological deficits, neuropsychiatric symptoms (e.g., personality changes), and headaches. Seizures may also occur but are less common. MRI of the brain with contrast typically shows a large (> 4 cm), solitary, ring-enhancing lesion. The diagnosis is confirmed with brain biopsy (when feasible).

A 52-Year-Old Man Is Brought to the Emergency Department Because