Central Nervous System Involvement of Natural Killer and T Cell Neoplasms

Purpose of Review: Peripheral natural killer (NK) and T cell neoplasms comprise approximately 10–15% of non-Hodgkin lymphomas. There are 27 different subtypes of peripheral NK and T cell neoplasms, each of which is relatively uncommon. Treatment has been largely extrapolated from case series, retrospective reports, and paradigms developed for the aggressive B cell lymphomas. This review explores the current knowledge of the characteristics, outcome, and treatment of CNS T cell and NK neoplasms. Recent Findings: Primary and secondary CNS NK and T cell malignancies confer significant morbidity and poor prognosis. Despite clinical heterogeneity between the 27 subtypes, high-dose methotrexate–based regimens seem most effective overall. The role of prophylaxis against secondary CNS involvement remains controversial. Autologous stem cell transplant and immunotherapy are potential for promising future therapies. Summary: Current understanding of incidence, outcome, and optimal treatment strategies for CNS T cell and NK neoplasms is limited, in large part due to their diversity and rarity. Prognosis is poor, except in a few reports of long-term survival in patients most often treated with combination therapy including high-dose methotrexate. A future prospective study on treatment and outcome in CNS T cell and NK neoplasms is needed to better define these diseases.