Aggressive NK Leukemia

Definition

Aggressive NK-cell leukemia is a disease with an aggressive, systemic proliferation of natural killer cells (NK cells) and a rapidly declining clinical course

Sample Cases

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Epidemiology

This disease has a very strong association with the Epstein-Barr virus (EBV) but the real  pathogenesis of this disease has yet to be described. The cell of origin is believed to be an Natural Killer cell. Blastoid NK cell lymphoma appears to be a different entity and shows no association with EBV.

Possible causes

Unknown.

Morphology

Peripheral blood    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   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. Other organs    Leukemic involvement of organs is typically destructive on tissue sections with necrosis and possibly angioinvasion, and the monotonous infiltrate may be diffuse or patchy.

A) Lymph node biopsy. Monomorphous infiltrate of medium-sized cells with scant cytoplasm, round nuclear contours, finely granular chromatin, and numerous mitotic figures B) Bone marrow core biopsy specimen. Hypercellular marrow with trilineage hematopoiesis and an interstitial infiltrate of immature blastlike cells C) Peripheral blood smear after bone marrow transplantation. Immature blasts with high nuclear-to-cytoplasmic ratio, agranular cytoplasm, and round nuclear contours

Immunophenotyping

The immunophenotype of mature T Cell and NK Cell Neoplasia is the same as extranodal NK/T-cell lymphoma, nasal type and is shown in the table below. In addition CD11b and CD16 show variable expression.

Other relevant tests

Cytochemistry:

Genetics:  

Sub-classification

Flow Diagnosis

References

1. Chan JK, Sin VC, Wong KF, Ng CS, Tsang WY, Chan CH, Cheung MM, Lau WH. "Nonnasal lymphoma expressing the natural killer cell marker CD56: a clinicopathologic study of 49 cases of an uncommon aggressive neoplasm." Blood. 1997 Jun 15;89(12):4501-13. PMID: 9192774

2. http://wikipedia.com

3.

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