Mixed-Phenotype Acute Leukemia: Diagnostic Criteria and Pitfalls

Arch Pathol Lab Med. 2017 Nov;141(11):1462-1468. doi: 10.5858/arpa.2017-0218-RA.


Mixed-phenotype acute leukemia (MPAL) is a heterogeneous category in the World Health Organization classification that comprises acute leukemias with discrete admixed populations of myeloid and lymphoid blasts ("bilineal") or with extensive coexpression of lymphoid and myeloid markers in a single blast population ("biphenotypic"). Flow cytometric findings suggestive of MPAL are often met with consternation by pathologists and oncologists alike, owing to unfamiliarity with the disease and uncertainty about how MPAL fits into established paradigms for treatment of acute leukemia. The purpose of this review is to explain the diagnostic criteria for MPAL, summarize its biological and clinical features, and address common diagnostic pitfalls of these unusual leukemias.

Publication types

  • Review

MeSH terms

  • Biomarkers, Tumor / blood
  • Biomarkers, Tumor / metabolism
  • Diagnosis, Differential
  • Fusion Proteins, bcr-abl / blood
  • Fusion Proteins, bcr-abl / genetics
  • Fusion Proteins, bcr-abl / metabolism
  • Histone-Lysine N-Methyltransferase / blood
  • Histone-Lysine N-Methyltransferase / genetics
  • Histone-Lysine N-Methyltransferase / metabolism
  • Humans
  • Immunohistochemistry / trends
  • Immunophenotyping / trends
  • Leukemia, Biphenotypic, Acute / diagnosis*
  • Leukemia, Biphenotypic, Acute / genetics
  • Leukemia, Biphenotypic, Acute / metabolism
  • Leukemia, Biphenotypic, Acute / therapy
  • Myeloid-Lymphoid Leukemia Protein / blood
  • Myeloid-Lymphoid Leukemia Protein / genetics
  • Myeloid-Lymphoid Leukemia Protein / metabolism
  • Practice Guidelines as Topic*
  • Prognosis
  • Translocation, Genetic
  • World Health Organization


  • BCR-ABL1 fusion protein, human
  • Biomarkers, Tumor
  • KMT2A protein, human
  • Myeloid-Lymphoid Leukemia Protein
  • Histone-Lysine N-Methyltransferase
  • Fusion Proteins, bcr-abl