Usefulness of anti-CD117 in the flow cytometric analysis of acute leukemia

We assessed the diagnostic usefulness of adding anti-CD117 to our existing flow cytometric profile in the analysis of 150 consecutive cases of acute leukemia (de novo or relapsed acute myelogenous leukemia [AML], AML arising in myelodysplastic syndrome, blast crisis of chronic myelogenous leukemia [CML], acute lymphoblastic leukemia, acute unclassifiable leukemia, and biphenotypic leukemia). CD117 was expressed on more than 10% of blasts in 64% of de novo AMLs (42/66), 95% of relapsed AMLs (19/20), 75% of AMLs arising from a myelodysplastic syndrome (6/8), and 25% of myeloid blast crisis in CMLs (1/4). CD117 was not expressed in acute lymphoblastic, acute biphenotypic, or unclassified leukemia or lymphoid blast crisis of CML. The specificity, positive predictive value, sensitivity, and negative predictive value of CD117 for AML were 100%, 100%, 69%, and 62%, respectively. CD117 is a specific marker for myeloblastic leukemias. Sensitivity is greatest in French-American-British M2 and relapsed AML. Intensity of CD117 expression is dim. Despite the high specificity and positive predictive value, the addition of anti-CD117 to our panel did not prove essential for the assignment of blast lineage.