[1459] Utility of Flow Cytometry Analysis of Maturing Myeloid Cells in the Diagnosis of Myelodysplastic Syndrome

JC Wallentine, RW Stuart, S Hill, JH Greenwood, SL Perkins, DW Bahler. University of Utah School of Medicine, Salt Lake City, UT; ARUP Laboratories, Salt Lake City, UT

Background: The diagnosis of myelodysplastic syndrome (MDS) currently involves assessing clinical, morphologic, and cytogenetic findings. Flow cytometry has the potential for identifying neoplastic myeloid cell populations but is not widely utilized for this purpose when evaluating possible MDS cases.
Design: Twelve cases of well-documented MDS with 5-color bone marrow flow cytometry studies were retrospectively identified. Flow cytometry findings were compared to 6 control bone marrows submitted for lymphoma/tumor staging. Kinetic studies were also done on control marrow specimens held at room temperature for 4 days to evaluate potential changes in antigen expression due to specimen aging.
Results: The 12 MDS cases consisted of 5 MDS-unclassified, 1 refractory cytopenia with multilineage dysplasia, and refractory anemia with excess blasts, type 1(4 cases), and type 2(2 cases). All 6 control cases showed the highest percentages of CD11b+ myeloid cells (93% ± 5%), followed by CD16+ cells (80% ± 7%), and CD10+ cells (43% ± 17%), which parallels their appearance during myeloid maturation,(i.e. CD11b before CD16 before CD10). In contrast, asynchronous expression of these antigens was observed in 6 MDS cases, with 3 having equal or more CD16+ myeloid cells compared to CD11b+ cells, and 3 cases having equal or more CD10+ cells than CD16+ cells. In addition, the myeloid cells lacked CD13 expression in 1 case, lacked CD33 in 1 case, and showed aberrant expression of CD56 in 1 case. Although left shifts were associated with lower percentages of CD11b, CD16, and CD10 positive myeloid cells, asynchronous expression patterns were not observed. Lower expression of CD11b, CD16, CD10, CD13, and CD33 was sometimes observed on control myeloid cells in the kinetic studies over increasing time, but were often minimal, and if present, similarly affected most antigens.
Conclusions: Flow cytometry can often identify aberrant antigen expression patterns on maturing myeloid cells in patients with MDS. Asynchronous expression of CD11b, CD16, and CD10 on maturing myeloid cells may be relatively common in MDS, is straightforward to identify, and is not related to left shifting or changes in antigen expression related to specimen age. Identification of asynchronous expression on maturing myeloid cells, along with other abnormal expression patterns, should help in the identification and diagnosis of clonal myeloid processes such as MDS.
Category: Hematopathology

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 177, Tuesday Afternoon

 

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