Clinical features and incidence of central nervous system involvement in patients with adult T‐cell leukaemia/lymphoma

Central nervous system (CNS) involvement is a known complication of adult T-cell leukaemia/lymphoma (ATL), but its clinical characteristics and incidence still remain unclear. This study characterized the clinical features and incidence of CNS involvement in patients with ATL (CNS-ATL). Overall, 213 patients diagnosed with aggressive ATL were retrospectively analysed at the Kagoshima University Hospital between 2002 and 2021. Of which, 28 (13.1%) developed CNS-ATL. Patients with CNS-ATL observed at ATL diagnosis were classified as acute (n = 21, 75%), lymphoma (n = 1, 3.6%) or chronic (n = 5, 17.9%); CNS-ATL observed post-ATL diagnosis comprised 10.2% (10/98) acute, 1.8% (1/54) lymphoma and 16.1% (5/31) chronic cases. Of the 28 patients, 11 (39.3%) had asymptomatic meningeal involvement detected at prophylactic intrathecal therapy, 10 (35.7%) exhibited neurological symptoms at ATL diagnosis, 4 developed symptomatic CNS involvement during induction therapy and 3 experienced CNS relapse post-treatment. Two-year overall survival of CNS-ATL was significantly lower than that of non-CNS-ATL, whereas 1-year cumulative incidence of CNS involvement post-ATL diagnosis was 12.3%. In conclusion, CNS involvement in ATL tends to occur early in the disease course and is associated with a poor prognosis, with a tendency for a higher incidence in acute-type than in lymphoma-type ATL.