Importance of CD117 in the evaluation of acute leukemias by flow cytometry.

Background: The issue of which specific antibodies need to be used when evaluating acute leukemias by flow cytometry is controversial.

Methods: Recent studies have suggested that antibodies against CD117 or c-kit are not essential for the assignment of blast lineage by flow cytometry, even though CD117 appears to be a very specific marker for myeloid lineage acute leukemias. We report a case of acute myeloid leukemia M2 subtype with an 8:21 translocation, where the leukemic blasts expressed CD117, CD19, and CD15 but did not show definitive expression of the myeloid markers CD13 or CD33.

Results And Conclusions: This study highlights the importance of CD117 when evaluating acute leukemias by flow cytometry, which was necessary in this case to suggest that the blasts were phenotypically abnormal myeloblasts. In addition, this case presented an unusual acute myeloid leukemia phenotype that will likely be encountered by others and could be difficult to interpret.