ABSTRACT
Introduction 1329 Historical perspectives 1329 Natural killer cell lymphomas 1330 Epstein-Barr virus infection of natural killer lymphoma cells 1330 Clinical features of natural killer cell lymphomas 1330 Nasal natural killer cell lymphoma 1331 Non-nasal natural killer cell lymphomas 1331 Aggressive natural killer cell leukemia/lymphoma 1331 Patterns of dissemination of natural killer cell lymphomas 1333 Peripheral blood and marrow involvement in nasal and 1333
non-nasal natural killer cell lymphomas Staging and assessment of natural killer cell lymphomas 1333 Staging of natural killer cell lymphomas 1333 Initial assessment of nasal natural killer cell lymphoma 1334 Initial assessment of non-nasal natural killer cell lymphomas 1335
and aggressive natural killer cell lymphoma/leukemia Quantification of circulating plasma Epstein-Barr virus DNA 1335 Treatment of natural killer cell lymphoma 1336
Radiation therapy 1336 Chemotherapy 1337 Combined chemotherapy and radiation therapy 1337 Prognostic factors of natural killer cell lymphomas 1337 Patient monitoring after treatment 1338 High-dose chemotherapy and hematopoietic stem cell 1338
transplantation in natural killer cell lymphomas Additional treatment options for refractory natural killer 1340
cell lymphomas Management of local problems in nasal natural killer cell 1340
lymphomas Post-transplantation lymphoproliferative diseases of 1341
natural killer cell lineage Chronic active Epstein-Barr virus infection 1341 Blastic natural killer cell lymphoma 1341 Future perspectives 1341 Key points 1341 References 1341
Natural killer (NK) cells are cytolytic cells capable of killing a variety of target cells, including tumor cells and cells infected with bacteria and viruses.1 Morphologically, NK cells are lymphocytes showing pale cytoplasm with azurophilic granules. Immunophenotypically, NK cells express variably the T lineage-associated antigens, such as CD2, CD7, and CD8. They are typically negative for surface CD3, but they do express the cytoplasmic CD3 epsilon (ε) chain. Natural killer cells also express a number of ‘NKassociated’ markers, including CD16, CD56, and CD57.2
Of these, CD56 is the most consistently expressed, and has been designated as a marker for NK cells. However, CD56 is not entirely specific for NK cells, and can also be found on NK-like T cells, neural and neuroendocrine tissues, and sometimes on skeletal muscles.3
