[1519] Chronic Lymphoproliferative Disorder of Natural Killer Cells (CLPD-NK): A Singular Entity Resembling T-Cell Large Granular Lymphocytic Leukemia (T-LGL) or a Heterogeneous Group of Conditions?

Damian J Tagliente, Rebecca L King, Jadee Neff, Grzegorz S Nowakowski, Matthew T Howard, William G Morice II. Mayo Clinic, Rochester, MN; University of Pennsylvania Perelman School of Medicine, Philadelphia, PA

Background: Natural killer cell (NK cell) leukemias that are not EBV-associated are rare, and their clinical attributes are poorly characterized. Early descriptions emphasized aggressive behavior, whereas more recent studies have portrayed a usually indolent condition with variably associated cytopenias, akin to T-cell large granular lymphocytic leukemia (T-LGL). In the most recent WHO classification scheme, these entities are categorized as chronic lymphoproliferative disorders of NK cells (CLPD-NK), yet the disease presentation and outcome remains ill-defined. To address this issue, a group of well-characterized cases were studied.
Design: Clinical and laboratory data from 34 CLPD-NK cases in the files of a major medical center from 1992-2012 were examined and compared.

CBC and Clinical Data from CLPD-NK Cases
Median Age, (y)59
% Hemoglobin<11.0 g/dL32%
%ANC<1.5 x 10(9)/L36%
%Platelet<150 x 10(9)/L15%
%Abs Lymph Count>2.5 x 10(9)73%
%Splenectomy and/or Multi-agent Chemotherapy18%
ANC=Absolute neutrophil count, Abs=Absolute

As a group, the CLPD-NK had demographic and laboratory findings similar to T-LGL. Most treated cases received single agent therapy; 7 (21%) required more aggressive treatment due to severe cytopenias or symptoms. All but one of the 7 required splenectomy and, 4 of the 7 were bone marrow transplant candidates. Transplantation was performed in 2 (one died of disease, one long term remission). One died of disease prior to transplantation, and one is awaiting the procedure. Overall, 5 of the 7 died of disease.

Clinicopathologic Features of Indolent and Aggressive Cases
%ALC>2.5 x 10(9)74%57%
%LDH>250 U/L33%57%
Average % Marrow Cellularity56%81%
Average % Marrow Involvement11%18%
ALC=Absolute lymphocyte count, LDH=Lactate dehydrogenase

Apart from marrow cellularity, the blood findings and bone marrow pathology were not predictive of aggressiveness. Two aggressive cases had extensive liver involvement, one of which also had multiple positive pleural fluid cytologies.
Conclusions: Globally, the features of CLPD-NK resemble T-LGL. However, this cohort revealed 3 groups: those not needing treatment, those requiring mild treatment, and those having aggressive disease. This heterogeneity challenges their inclusion in a single diagnostic category.
Category: Hematopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 236, Monday Morning


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