[1580] Blast Immunophenotypes by Flow Cytometry in Acute Myeloid Leukemia with Myelodysplasia-Related Changes

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

Background: There is little data on the immunophenotype (IP) of acute myeloid leukemia with myelodysplasia-related changes (AML-MDS). We therefore sought to systematically study the blast IPs in this subgroup by flow cytometry (FC), compared to therapy-related AMLs (t-AMLs) and AMLs with normal cytogenetics (AML-nCG), with an emphasis on cytogenetic (CG) correlations.
Design: AML-MDSs and t-AMLS were defined according to 2008 WHO criteria; AML-nCGs had >20% blasts with a normal karyotype. Cases with t(15;17)/t(16;16)/t(8;21)/11q23 rearrangement by FISH were excluded. 4-color FC was performed on blood or bone marrow using the following antibodies: CD2, CD3, CD4, CD5, CD7, CD10, CD11b, CD13, CD14, CD15, CD16, CD19, CD20, CD22, CD33, CD34, CD36, CD38, CD45, CD56, CD64, CD117, HLA-DR, MPO and TdT. Blast aberrancies were defined as deviation from previously published IPs in normal myeloblasts.
Results: 30 AML-MDSs (17M/13 F; 31-85 years), 27 AML-nCGs (16M/11F; 22-83 years), and 8 t-AMLs (5M/3F; 50-72 years) were collected. The %blast by FC ranged from 0.2-96% (median 22%) in AML-MDSs, 5.2-93% (55%) in AML-nCGs, and 1.7-46% (15%) in t-AMLs. Median number of aberrancies was 7.5 in AML-MDSs (3-11/case) compared to 6 in AML-nCG (3-17) and 8 in t-AMLs (4-11). The most common aberrancies observed in AML-MDSs included: underexpression of CD33 (11/29 cases; 38%), CD34 (9/30; 30%), and HLA-DR (15/29; 52%); CD7 (13/30; 43%), CD15 (22/29; 76%), and TdT (6/16;38%) expression; overexpression of CD64 (10/29; 34%) and CD117 (9/30; 30%). The most common aberrancies observed in t-MDSs included: expression of CD15 (7/8; 88%), CD22 (4/8; 50%) and TdT (4/5; 80%); overexpression of CD34 (6/8; 75%) and underexpression of HLA-DR (5/8; 63%). The most common aberrancies observed in AML-nCGs included: CD7 (12/28; 43%), CD15 (25/27; 93%), and CD36 (14/29; 48%) expression; underexpression of CD34 (14/29; 48%) and HLA-DR (16/29; 55%). CD22 expression was only observed in AML-MDSs (2/28) and t-AMLs (4/8). 17 AML-MDSs had complex CG; 38 total AMLs (including AML-nCG, some AMLD-MDSs and t-AMLs) had normal CG. CD22 and CD56 expression was more commonly present in complex vs. normal CG cases (16% vs. 0%; p=0.02 and 29% vs. 5.3%; p=0.04 respectively); no other statistically significant relationships between CG and IP were identified.
Conclusions: Overall, the frequency and pattern of antigen expression did not differ substantially between AML-MDS, t-AML, and AML-nCG; no unique IP signature can be assigned to these diagnostic categories. CD22 and CD56 expression were present most commonly in cases with complex CG.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 219, Tuesday Morning

 

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