IJCEP Copyright © 2007-All rights reserved.
Int J Clin Exp Pathol 1(4):381-386;2008

Case Report
Hairy Cell Leukemia with Unusual Loss of CD103 in a Subset of the Neoplastic
Population: Immunophenotypic and Cell Cycle Analysis by Flow Cytometry

Constance M. Yuan and Li-Jun Yang

Department of Pathology, University of Florida College of Medicine, Gainesville, FL, USA and Laboratory of Pathology, National Cancer
Institute/National Institutes of Health, Bethesda, MD, USA

Received 4 Oct 2007; accepted and available online 1 January 2008

Abstract: We report an unusual case of hairy cell leukemia (HCL) in a 55-year-old male who presented with fatigue, increased bruising,
leukocytosis, anemia, thrombocytopenia and moderate splenomegaly without lymphadenopathy. Microscopically, a monomorphic population of
small to medium-sized lymphoid cells with bean-shaped nuclei, ground glass chromatin and fine cytoplasmic projections was identified in the
peripheral blood and bone marrow. Flow cytometric immunophenotyping demonstrated a monoclonal population of mature B cells with
coexpression of CD25, CD11c and CD103. The clonal B-cells all exhibited homogenous expression of CD20 and uniform light scatter
characteristics. However, CD103 expression was present in only half of the clonal B-cells. Flow cytometric cell cycle analysis using DRAQ5
DNA dye in intact live cells showed that both the CD103-positive and CD103-negative cell subsets exhibited a low S-phase fraction with no
significant difference between the two subpopulations. Clinical remission was achieved by treatment with 2-chlorodeoxyadenosine. Variant and
atypical cases of HCL have been described with varying intensity of CD11c, loss of CD25, aberrant expression of CD10, and lack of CD103
expression. However, the lack of CD103 in only a subset of the malignant cells in our case is an immunophenotypic aberrance that, to our
knowledge, has not been previously reported. (IJCEP710001).

Key Words: Hairy cell leukemia, flow cytometry, cell cycle, immunophenotype, DRAQ5, S-phase.

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Address all correspondence to: Constance M. Yuan, M.D., Ph.D., Flow Cytometry Unit, Laboratory of Pathology, Mail Stop 1500, Bldg 10-Rm
2N108, National Cancer Institute, National Institutes of Health (NCI/NIH), 9000 Rockville Pike, Bethesda MD 20892. Phone: (301) 496-4709;
Fax: (301) 402-0043; Email:
yuanc@mail.nih.gov