[1372] Diagnostic Value of CD31 Immunohistochemistry in Evaluation of Acute Myeloid Leukemia with Megakaryocytic Differentiation.

Mu Su, Dinesh Rakheja, Huan-You Wang, Franklin Fuda, Weina Chen. UT Southwestern Medical Center, Dallas, TX

Background: Platelet endothelial cell adhesion molecule-1 (PECAM-1, or CD31), a 130-kDa glycoprotein, is involved in megakaryopoiesis and used as an immunohistochemical (IHC) marker for megakaryocytic differentiation. However, a comprehensive immunophenotypic analysis of the utility of this marker in lineage assignment in acute myeloid leukemia (AML) has not been evaluated and is the focus of our study.
Design: IHC stains were performed on tissue microarray sections of 66 AML cases that encompass heterogeneous subtypes of AML except AML with t(15;17). The sections were stained for CD31 (clone JC70A, Dako), glycophorin A, CD61, and factor VIII. The immunophenotype in the corresponding blood/bone marrow specimens was analyzed by 4-color flow cytometry (FC).
Results: The demographic data and IHC and FC results are summarized in the table. Twenty cases were CD31(+) mainly with membranous staining pattern, while 46 cases were CD31(-). There were no age or gender differences between the two groups. Compared to CD31(-) group, CD31(+) AML cases were more likely to express HLA-DR, CD61, and factor VIII, and there was a trend towards higher frequency of CD36 expression. Approximately 30% of CD31(+) cases expressed more lineage specific megakaryocytic markers CD61 and/or factor VIII by IHC. In contrast, only one CD31(-) case (2%) partially expressed CD61. All cases were negative for glycophorin A. The expressions of other markers (CD7, CD11b, CD13, CD15, CD33, CD56, CD64, CD117, MPO and Tdt) were similar in two groups.

Immunophenotypic features in CD31(+) versus CD31(-) AML
 Mean AgeGender (M/F)HLA-DR (FC)CD36 (FC)CD61 (IHC)Factor VIII (IHC)
CD31- (P/N)5121/2524/217/381/411/37
CD31+ (P/N)4612/817/36/146/145/15
p value0.2810.4220.0410.1860.0350.016
P, positive; N, negative; M, male; F, female; FC, flow cytometry; IHC, immunohistochemistry.

Conclusions: Our results indicate that CD31 is a sensitive but not lineage-specific marker of megakaryocytic differentiation, which is corroborated with known expression of CD31 on endothelial cells and hematopoietic cells including lymphocytes and monocytes. Therefore, a comprehensive immunophenotypic analysis is required for megakaryocytic lineage assignment in AML.
Category: Hematopathology

Monday, February 28, 2011 1:00 PM

Poster Session II # 186, Monday Afternoon


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