This rare form a leukemia is more common among Asians in comparison to other ethnic groups. It is typically diagnosed in adolescents and young adults, with a slight predominance in males.
This disease has a strong association with the Epstein-Barr virus (EBV), but the true pathogenesis of this disease has yet to be described. The cell of origin is believed to be an NK cell. Blastoid NK cell lymphoma appears to be a different entity and shows no association with EBV.
This disease is typically found and diagnosed in peripheral blood, and while it can involve any organ, it is usually found in the spleen, liver, and bone marrow.
The leukemic cells have a diameter mildly greater than a large granular lymphocyte (LGL) and have azurophilic granules and nucleoli of varying prominence. Nuclei may be irregular and hyperchromatic.
Bone marrow involvement runs the spectrum between an inconspicuous infiltrate to extensive marrow replacement by leukemic cells. Reactive histiocytes displaying hemophagocytosis can been seen interspersed in the neoplastic infiltrate.
Leukemic involvement of organs is typically destructive on tissue sections with necrosis and possibly angioinvasion, and the monotonous infiltrate may be diffuse or patchy.
The immunophenotype of this disease is the same as extranodal NK/T-cell lymphoma, nasal type and is shown in the table below. CD11b and CD16 show variable expression.
Due to the NK lineage, clonal rearrangements of lymphoid (T cell receptor; B cell receptor) genes are not seen. The genome of the Epstein Barr virus (EBV) is detected in many cases, along with a variety of chromosomal abnormalities.
Currently Aggressive NK-cell leukemia, being a subtype of PTCL, is treated similarly to B-cell lymphomas. However, in recent years, scientists have developed techniques to better recognize the different types of lymphomas, such as PTCL. It is now understood that PTCL behaves differently from B-cell lymphomas and therapies are being developed that specifically target these types of lymphoma. Currently, however, there are no therapies approved by the U.S. Food and Drug Administration (FDA) specifically for PTCL. Anthracycline-containing chemotherapy regimens are commonly offered as the initial therapy. Some patients may receive a stem cell transplant. Novel approaches to the treatment of PTCL in the relapsed or refractory setting are under investigation.
^ abcdeChan JK, Sin VC, Wong KF, et al. (June 1997). "Nonnasal lymphoma expressing the natural killer cell marker CD56: a clinicopathologic study of 49 cases of an uncommon aggressive neoplasm". Blood89 (12): 4501–13. PMID9192774.
^ abcImamura N, Kusunoki Y, Kawa-Ha K, et al. (May 1990). "Aggressive natural killer cell leukaemia/lymphoma: report of four cases and review of the literature. Possible existence of a new clinical entity originating from the third lineage of lymphoid cells". Br. J. Haematol.75 (1): 49–59. doi:10.1111/j.1365-2141.1990.tb02615.x . PMID2375924.