[1581] Flow Cytometric Blast Immunophenotype in Acute Myeloid Leukemias Arising from Non-Acute Myeloid Disorders

James Vaughan, Horatiu Olteanu, Steven H Kroft, Alexandra M Harrington. Medical College of Wisconsin, Milwaukee, WI

Background: Non-acute myeloid disorders can progress to acute myelogenous leukemia (AML). No data exist comparing blast immunophenotypes (IP) pre- and post-transformation. As the blasts in non-acute myeloid disorders have been demonstrated to be CD34(+) by flow cytometry (FC) in most cases, we hypothesized that transformed cases would retain this IP.
Design: 9 cases of non-acute myeloid disorders with transformation to AML were identified. Classification followed the 2008 WHO. Pre and post-transformation blast IPs were determined by cluster analysis and 4-color FC in blood or bone marrow with the following antibodies: CD3, CD4, CD5, CD7, CD8, CD10, CD11b, CD13, CD14, CD15, CD16, CD19, CD20, CD22, CD33, CD34, CD36, CD38, CD45, CD56, CD64, CD79a, CD117, HLA-DR, MPO and TdT. Blast aberrancies were defined as deviation from previously published IPs in normal myeloblasts. Change in antigen (Ag) expression was defined as 1/4 log change.
Results: The study included 5 M and 4 F, aged 46-68 years (median 62) with refractory anemia with excess blasts (RAEB)-2 (n=4), therapy-related myelodysplastic syndrome (MDS) (2), RAEB-1 (2), and CMML-2 (1). Pre-transformation blast % by FC ranged from 1.7-17% (median 6); the number of IP aberrancies ranged from 2-9/case (median 5) with the most common aberrancies present in CD15 (7/8; 88%), HLA-DR (6/8; 75%), CD34 (6/9; 67%), CD13 (5/9; 56%), and CD33 (5/9; 56%). The time from diagnosis to transformation ranged from 23-801 days (median 330). The blast % by FC in AMLs ranged from 0.59-54% (median 11) with 4-11 IP aberrancies per case (median 6). The most common aberrancies were in CD15 (7/9; 78%), CD34 (7/9; 78%), CD13 (6/9; 67%), HLA-DR (6/9; 67%), CD33 (5/9; 56%), CD7 (5/9; 56%) and CD117 (5/9; 56%). Ag changes between pre and post-transformation cases were present in 7/9 cases, ranging from 3-9 per case (median 5) for a total of 36/156 Ags examined (23%). These changes included gain of Ag expression (n=8), loss of Ag expression (n=7), and change in Ag expression intensity (n=21). The most common changes were in CD13 (6/9; 67%), CD38 (3/6; 50%), CD33 (4/9; 44%), and HLA-DR (4/9; 44%). CD34 expression was the same in 8/9 cases (1 negative, 3 positive, 2(partial+), 2(bright+)), with one case showing change in intensity: (+) to (bright +).
Conclusions: The blasts in MDSs and transformed AMLs have multiple immunophenotypic aberrancies at diagnosis. The blast IP frequently changes during transformation with the most common changes observed in Ag expression intensity; however, CD34 expression remained relatively the same pre- and post-transformation.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 218, Tuesday Morning


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