Acute leukemias of ambiguous origin

Area of Science:

• Hematopathology
• Hematology
• Oncology

Background:

• Acute leukemias of ambiguous lineage present diagnostic challenges.
• The Society for Hematopathology/European Association for Haematopathology Workshop addressed these complex cases.

Purpose of the Study:

• To provide an overview of mixed-phenotype acute leukemia (MPAL) based on WHO classification.
• To summarize diagnostic criteria for MPAL subtypes.
• To discuss diagnostic challenges and pitfalls.

Main Methods:

• Review of MPAL cases submitted to a workshop.
• Application of comprehensive immunophenotyping using flow cytometry.
• Confirmatory immunohistochemical and cytochemistry studies.

Main Results:

• B/myeloid and T/myeloid MPAL were the most frequent types observed.
• Diagnostic accuracy requires a comprehensive immunophenotyping approach.
• Rare cases of B-acute lymphoblastic leukemia (B-ALL) may express myeloperoxidase.

Conclusions:

• MPAL diagnosis is challenging.
• Inadequate flow cytometry panels contribute to diagnostic difficulties.
• Accurate MPAL diagnosis relies on thorough and comprehensive methodology.