Lineage determination in mixed phenotype acute leukemia

Abstract

Letter to the Editor Response to Marcondes et al.Dear Dr. Marcondes et al.Thank you very much for your interest in our CSI case 2, mixed phenotype acute leukemia (MPAL).1 Your comments raise interesting questions about the diagnostic criteria for MPAL: in particular, the nature of a small subset of myeloperoxidase positive (MPO, +) myeloblasts and the threshold for MPO positivity by flow cytometry.The presence of a small subset of MPO(+) blasts in a background of a larger subset of MPO(-) blasts in our case raises the possibility that there are two distinct and separate blast populations. Our conclusions seem to differ from yours in the nature of this small subset of MPO(+) cells. As such, we will attempt to delineate our thoughts on this subject.