[1154] Flow Cytometric Panel Including CD10, CD19, CD38, CD58 and CD45 Increases Diagnostic Accuracy for Distinguishing Hematogones from Precursor B-Cell Acute Lymphoblastic Leukemia (Pre B-ALL)

S Alkan, R Veerappan, P Fitting, M Velankar, S Bozkurt. Loyola University Medical Center, Maywood, IL

Background: Hematogones are benign precursor B-lineage lymphoid population that are seen in increased numbers in the bone marrow during of childhood, post bone marrow transplant, immune deficiency and autoimmune disorders. They typically show expression of dim CD45, CD10, CD34, CD19, TdT and variable CD20. However, this phenotype is also seen in patients with precursor B-cell acute lymphoblastic leukemia (pre B-ALL) causing a significant problem in distinguishing residual pre B-ALL from hematogones in a regenerating marrow. Earlier studies suggested flow cytometric analysis using the above markers as being useful for differentiating hematogones from pre B-ALL, however, in our experience the use of these limited panel of markers is insufficient and may hinder correct interpretation of bone marrow samples. Recent studies showed that CD58 is commonly expressed in pre B-ALL but not in hematogones and expression of CD38 is different in the two populations. We generated a 5-color antibody panel including the markers mentioned above to assess the feasibility of using a novel panel to distinguish pre B-ALL from hematogones.
Design: Total of 37 cases including 27 cases of pre B-ALL (diagnostic and residual/relapsed cases) and 10 cases of hematogones were analyzed by five color flow cytometery. Two separate tubes with following markers (Tube1:CD38-PE, CD10-FITC, CD19-ECD, CD20-PC5, CD45-PC7 and tube2: CD58-PE, CD10-FITC, CD19-ECD, CD34-PC5, CD45-PC7) were used simultaneously with the standard acute leukemia panels. Results were correlated with the bone marrow histologic findings and cytogenetic analysis.
Results: Hematogones typically showed expression of bright CD38, moderate (mod) CD19, mod CD10, variable CD20 and no CD58; in contrast pre B-ALL showed weak to mod CD38, mod to strong CD19, mod to strong CD10 and mod CD58. Without the combination of both CD38 and CD58 together, some cases would have been difficult to interpret.
Conclusions: Combination of CD38 and CD58 increases the diagnostic accuracy in differentiation of hematogones from pre B-ALL. Based on this analysis, we recommend diagnostic laboratories to include these markers in their routine evaluation of bone marrow samples that are submitted for acute leukemia evaluation especially post treatment samples in order to prevent misdiagnosis.
Category: Hematopathology

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 170, Wednesday Afternoon