B/myeloid MPAL is the common MPAL immunophenotype, representing ~50–60% of the total MPAL cases, and possesses a heterogeneous group of gene alterations in B-lineage transcriptional regulators (PAX5 and IKZF1 (Ikaros)), as well as somatic mutations in epigenetic modifiers (TET2, EZH2, and ASXL1) [15,18]. Here, PAX5 is linked to mixed phenotype acute leukemia.