[1350] EBV Negative Aggressive NK-Cell Leukemia: Occurrence in Non-Asian Patients with a Uniformly Dismal Outcome

MT Howard, WG Morice, JP Maciejewski, N Bejanyan, ED Hsi. Mayo Clinic, Rochester, MN; Cleveland Clinic, Cleveland, OH

Background: Aggressive NK-cell leukemia (ANKL) is a rare NK-cell neoplasm almost exclusively found in Asian populations and which is typically Epstein-Barr virus (EBV) associated. EBV negative ANKL has been sporadically reported and it has been suggested that such cases have a relatively favorable prognosis. We report 4 patients from the midwestern United states with EBV negative ANKL.
Design: Records were reviewed at Cleveland Clinic and Mayo Clinic from 2003-2009 to find cases of EBV negative aggressive NK-cell leukemia.
Results: The 4 patients had a mean age of 38.5 years, and 3 were female. Splenomegaly was present in all patients. No patients were Asian. All patients followed an aggressive clinical course, and median survival time was 13 months (Table 1).

Table 1. Demographic and Clinical Data

Patient	Age (years)	Splenomegaly	Hepatomegaly	Absolute Lymphocyte Count	Absolute Neutrophil Count	Hgb	Survival (months)
1	31	Yes	Yes	1.668	2.990	10.7	0.5
2	63	Yes	No	45.236	5.786	7.6	1
3	25	Yes	No	4.784	3.312	8.9	21
4	35	Yes	No	4.250	8.130	12.8	13

In all cases an immunophenotypically abnormal CD2 positive, CD3 and CD4 negative NK-cell population was identified. Flow cytometry for killer cell immunoglobulin-like receptors (KIR) was performed on 2 patients. One had restriction to CD158b, while the other patient lacked KIR expression. The remaining immunophenotypic and cytogenetic attributes are summarized in Table 2. Cytogenetics revealed a complex karyotype with abnormalities of chromosomes 7 and X in one patient, a 46,X,t(X;5)(p11.2q11.2)[11]/46,XX[cp9] in one patient, and normal karyotypes in the remaining patients.

Table 2. Immunophenotypic Data

Patient	CD5	CD7	CD8	CD16	CD56	CD94	CD161
1	+	+	+	N	+	N	N
2	-	-	-	N	+	N	N
3	-	-	-	-	+	+	-
4	-	+	-	+	+	+	+

N = Not Performed


Conclusions: EBV-negative ANKL is a rare disorder which has similar clinical and laboratory features and as dismal an outcome as EBV-positive ANKL. Unlike EBV-positive ANKL, EBV-negative cases does not appear to have a proclivity to occur in Asian populations. The reasons for these differences are unclear, however this data suggests that EBV infection may not play on obligate role in oncogenesis in at least a subset of cases.
Category: Hematopathology

Monday, March 22, 2010 1:00 PM

Poster Session II # 140, Monday Afternoon