• aggressive NK cell leukaemia;
  • chronic active EBV infection;
  • Epstein–Barr virus;
  • extranodal NK/T-cell lymphoma;
  • nasal type;
  • T/NK-cell lymphoproliferative disorders

Takahashi E, Ohshima K, Kimura H, Hara K, Suzuki R, Kawa K, Eimoto T & Nakamura S for the NK-cell Tumor Study Group (2011) Histopathology59, 660–671

Clinicopathological analysis of the age-related differences in patients with Epstein–Barr virus (EBV)-associated extranasal natural killer (NK)/T-cell lymphoma with reference to the relationship with aggressive NK cell leukaemia and chronic active EBV infection-associated lymphoproliferative disorders

Aims:  Extranodal natural killer (NK)/T-cell lymphoma (NKTL), comprising nasal NKTL and extranasal NKTL (ENKTL), is associated with Epstein–Barr virus (EBV). A bimodal age distribution was noted in NKTL patients. We examined the clinicopathological differences between two age groups of ENKTL patients (= 23) and compared the findings with those of aggressive NK cell leukaemia (ANKL; = 10) and monoclonal chronic active EBV infection-associated T/NK-cell lymphoproliferative disorders [chronic active EBV infection/TNK-lymphoproliferative disorders (CAEBV/TNK-LPD)] of NK-cell type (= 45).

Methods and results:  Distinct differences existed between elderly (>50 years; = 13) and younger (≤50 years; = 10) ENKTL patients; the latter showed a higher disease stage (= 0.0286), worse performance status (= 0.0244), more frequent B symptoms (= 0.0286) and more frequent liver, spleen and bone marrow involvement (= 0.0222, 0.0005 and 0.0259, respectively). Few clinicopathological differences existed between younger ENKTL and ANKL patients. Patients with monoclonal CAEBV/TNK-LPD of NK-cell type (= 45) showed features similar to those in younger ENKTL/ANKL patients, except a more juvenile onset of CAEBV-related symptoms and better prognosis. However, the onset age of overt leukaemia/lymphoma in CAEBV/TNK-LPD patients and overall survival thereafter were similar to those in younger ENKTL/ANKL patients.

Conclusions:  ENKTL (≤50 years) is distinct from that in elderly patients and may encompass ANKL and overlap in the clinicopathological profile with NK-cell type CAEBV/TNK-LPD.