Central Nervous System Involvement of Natural Killer and T Cell Neoplasms

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.

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. 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.