Requirements for assigning more than one lineage to a single blast population in mixed phenotype acute leukemia (MPAL)
| Myeloid lineage |
| Myeloperoxidase (flow cytometry, immunohistochemistry, or cytochemistry) |
| or |
| Monocytic differentiation (at least 2 of the following: nonspecific esterase, CD11c, CD14, CD64, lysozyme) |
| T lineage |
| Cytoplasmic CD3 (flow cytometry with antibodies to CD3 epsilon chain; immunohistochemistry using polyclonal anti-CD3 antibody may detect CD3 zeta chain, which is not T cell–specific) |
| or |
| Surface CD3 (rare in mixed phenotype acute leukemia) |
| B lineage (multiple antigens required) |
| Strong CD19 with at least 1 of the following strongly expressed: CD79a, cytoplasmic CD22, CD10 |
| or |
| Weak CD19 with at least 2 of the following strongly expressed: CD79a, cytoplasmic CD22, CD10 |
| Myeloid lineage |
| Myeloperoxidase (flow cytometry, immunohistochemistry, or cytochemistry) |
| or |
| Monocytic differentiation (at least 2 of the following: nonspecific esterase, CD11c, CD14, CD64, lysozyme) |
| T lineage |
| Cytoplasmic CD3 (flow cytometry with antibodies to CD3 epsilon chain; immunohistochemistry using polyclonal anti-CD3 antibody may detect CD3 zeta chain, which is not T cell–specific) |
| or |
| Surface CD3 (rare in mixed phenotype acute leukemia) |
| B lineage (multiple antigens required) |
| Strong CD19 with at least 1 of the following strongly expressed: CD79a, cytoplasmic CD22, CD10 |
| or |
| Weak CD19 with at least 2 of the following strongly expressed: CD79a, cytoplasmic CD22, CD10 |