IJCEP Copyright © 2007-All rights reserved.
Int J Clin Exp Pathol 1(6):544-549;2008

Case Report
Diagnostic Challenges Related to Myeloid/Natural Killer Cells, a Variant of Myeloblasts

Guilin Tang, Franciose Truong, Oluwole Fadare, Bruce Woda and Sa A. Wang

Department of Pathology, UMass Memorial Medical Center, University of Massachusetts School of Medicine, Worcester, MA; Department of
Pathology, Wilford Hall Medical Center, Lackland Air Force Base, TX; Department of Pathology, University of Texas Health Science Center at San
Antonio, San Antonio, TX

Received 16 Dec 2007; Accepted and available online 28 Jan 2008

Abstract: The authors report herein two diagnostically challenging cases centered on the myeloid/natural killer (myeloid/NK) cells, a variant of
myeloblasts, to illustrate the importance of advanced flow cytometric immunophenotyping and an updated understanding of surface markers in
hematopoietic malignancies. Myeloid/NK cell acute leukemia is a very rare subtype of leukemia. Although its NK-cell nature is debatable, it
represents a variant of leukemia with distinct morphological and immunophenotypical features. The first case is a de novo myeloid/NK-cell
acute leukemia with a striking clinical, morphologic and immunophenotypic resemblance to acute promyelocytic leukemia (APL), but which
could be distinguished by its CD11a, CD18, CD117 and CD9 expression. This case illustrates the importance of utilizing the APL surrogate
surface phenotype of HLA-DRlow, CD11alow and CD18low by flow cytometric study to rule in/out APL immunophenotypically. In the second
case, we show that myeloid/NK-cell blasts can present as a variant of blasts in a preleukemic disease as refractory anemia with excess
blasts-1 (RAEB-1), where the blasts were negative for CD34, CD117 and HLA-DR. The recognition of such blast variant is important in
appropriately classifying such preleukemic diseases by blast percentage. (IJCEP712004).

Key Words: Acute leukemia, flow cytometric immunophenotyping, myeloblast, natural killer cell

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Address all correspondence to:  Sa A. Wang, MD, Department of Pathology, 3 Biotech, 1 Innovation Drive, Worcester, MA 01605, USA
Phone: 508-793-6174, Fax: 508-793-6110, Email:
wanga@ummhc.org