[1417] Utility of CD11a and CD18 in the Diagnosis of Acute Promyelocytic Leukemia by Flow Cytometric Immunophenotyping.

Yi Zhou, Jeffrey L Jorgensen, Sa A Wang, L Jeffrey Medeiros, Sergej N Konoplev. University of Texas MD Anderson Cancer Center, Houston

Background: Acute promyelocytic leukemia (APL) is a curable disease, but it can be rapidly fatal if the patient is not diagnosed and treated in a timely fashion. Flow cytometric immunophenotyping (FCI) has a rapid turn around time, and may serve as a screening test for confirmatory molecular/cytogenetic tests for t(15;17)(q22;q21/PML-RARA). CD34-/HLA-DR-/CD117+ is a well recognized phenotype for APL, but is known to lack specificity. The leukocyte integrin αL β2 (CD11a/CD18) is expressed in most cases of acute myeloid leukemia (AML). In a small number of published studies, CD11a/CD18 was often dim or negative in APL. The goal of this study was to examine CD11a/CD18 expression in a group of APL cases and in a group of AML cases in which APL was considered in the differential diagnosis.
Design: We retrospectively examined 83 cases of AML with a clinical, morphologic, or immunophenotypic suspicion for APL, for which CD11a and CD18 were added to our routine AML FCI panel (which also included CD34 and HLA-DR). A marker was scored as positive if 30% or more of the blasts were brighter than isotype controls. All cases of APL were confirmed by molecular/cytogenetic testing.
Results: There were 43 cases of APL and 40 cases of non-APL, which were mostly AML with or without maturation (WHO criteria). The results for CD11a, CD18, CD34 and HLA-DR were as follows. Considering these markers singly, HLA-DR (absence) was the most sensitive for APL, but all single markers had low specificity in this study group. The classic CD34-/HLA-DR- pattern showed moderate sensitivity and specificity for APL. A pattern of negativity for CD11a and/or CD18 showed high sensitivity but lower specificity. Negativity for all four antigens had the highest specificity but lacked sensitivity.

 APL N (%)Non-APL N (%)Specificity
HLA-DR-42 (98)14 (35)65%
CD34-36 (84)16 (40)60%
CD11a-37(86)16 (40)60%
CD18-38 (88)20 (50)50%
CD11a- or CD18 -42 (98)26 (65)35%
CD34-/DR -35 (81)11 (28)72%
CD11a-/CD18 -33 (77)10 (25)75%
DR-/CD11a-/CD18-32 (74)6 (15)85%
CD34-/DR-/CD11a-/CD18-27 (63)4 (10)90%

Conclusions: CD11a and CD18 are useful markers in screening for APL by FCI, and are highly sensitive in combination. A case positive for both CD11a and CD18 would be very unusual for APL (<3% of APL cases in this series). However, most expression patterns of CD11a/CD18/CD34/HLA-DR showed limited specificity for APL, vs. a selected set of non-APL cases.
Category: Hematopathology

Monday, February 28, 2011 1:00 PM

Poster Session II # 185, Monday Afternoon


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