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

Takahashi E, Ohshima K, Kimura H, Hara K, Suzuki R, Kawa K, Eimoto T & Nakamura S for the NK‐cell Tumor Study Group
(2011) Histopathology 59 , 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 (n = 23) and compared the findings with those of aggressive NK cell leukaemia (ANKL; n = 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 (n = 45). Methods and results: Distinct differences existed between elderly (>50 years; n = 13) and younger (≤50 years; n = 10) ENKTL patients; the latter showed a higher disease stage (P = 0.0286), worse performance status (P = 0.0244), more frequent B symptoms (P = 0.0286) and more frequent liver, spleen and bone marrow involvement (P = 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 (n = 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.