CD4 and primary central nervous system lymphoma: In patients infected with human immunodeficiency virus (HIV), PCNSL is associated with CD4+ T-cell counts <50 cells/μL and concomitant Epstein–Barr virus (EBV) virus infection.[10] Memory loss and seizures occur more frequently in HIV patients (50% and 38%, respectively) than non-HIV patients (31% and 11%, respectively).[11] PCNSL presents with a varied symptomatology, including acute encephalopathy, which leads to diagnostic evaluation for infectious, inflammatory, metabolic, and neoplastic etiologies.