ZAP70 and B-cell chronic lymphocytic leukemia: EBV(+) patients with CLL presented more advanced disease, having a greater clinical disease burden (RAI and BINET scores) and higher values of unfavorable prognostic factors (B2M, LDH, percentage of CD19+ CD38+ and CD19+ ZAP70+ cells, deletion 11q) compared to EBV(−) patients.