Prognosis of aggressive adult T-cell leukemia/lymphoma with central nervous system infiltration and utility of CD7 versus CADM1 flowcytometric plots of cerebrospinal fluid

The prognosis of adult T-cell leukemia/lymphoma (ATL) with primary central nervous system (CNS) involvement has been unclear since the advent of new therapies. Recently, we have shown that flow cytometric CD7/CADM1 analysis of CD4 + cells (HAS-Flow) is useful to detect ATL cells that are not morphologically diagnosed as ATL cells. We investigated the role of CNS involvement in ATL using cytology and HAS-Flow by analyzing cerebrospinal fluid (CSF) from 73 aggressive ATL cases. Based on the findings in CSF, the study subjects were classified into CNS + (cytologically malignant, n = 18), CNS- (cytologically non-malignant and ATL cell population negative in HAS-Flow, n = 44), and CNS-Micro (cytologically non-malignant and ATL cell population positive in HAS-Flow, n = 11) groups. As expected, the CNS + group had a shorter overall survival than the CNS- groups (P < 0.001). However, the CNS-Micro group showed no adverse impact on overall survival compared to the CNS- group (P = 0.506), even without additional CNS-targeted treatments. HAS-Flow also demonstrated clinical utility in the diagnosis of CSF lesions in ATL patients with cerebral white matter lesions and in the detection of ATL cells on post-treatment CSF examination in patients with CNS involvement. Our study demonstrates that ATL with CNS involvement have a poor prognosis and that CSF HAS-Flow is useful to assist in the diagnosis of suspected CNS involvement and to detect ATL cells with high sensitivity after treatment.