CSF morphologic and flow cytometry findings during the treatment course. Pretreatment CSF showed definitive morphologic evidence of abnormal lymphocytes, with flow cytometry showing a prominent CD4 and CD8 double-positive population (green), consistent with involvement by T-PLL. Following triple therapy, the burden of disease was reduced but with persistent morphologic and flow cytometric evidence of disease. Following alemtuzumab therapy, the CSF was entirely cleared, with no morphologic or flow cytometric evidence of T-PLL (Wright Giemsa stain; original magnification ×1000).