Biphenotypic acute leukemia in adults.

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Leukemias typically involve a single cell lineage proliferation.
• Dual-lineage differentiation in leukemia is increasingly recognized, particularly in pediatric cases.
• Adult acute leukemias with mixed cell lineage require further characterization.

Purpose of the Study:

• To identify and characterize mixed lineage leukemias in adult acute leukemia cases.
• To investigate the immunophenotypic, cytochemical, and cytogenetic features of these mixed lineage leukemias.
• To determine the clinical behavior and prognostic implications of mixed lineage leukemias in adults.

Main Methods:

• Review of 118 adult acute leukemia cases.
• Immunophenotyping using immunofluorescent flow cytometry.
• Cytochemical evaluation with naphthol AS-D chloroacetate esterase stain.
• Cytogenetic analysis, including assessment of chromosome 11 abnormalities.

Main Results:

• Seven of 118 adult acute leukemia cases exhibited mixed cell lineage.
• Mixed lineage leukemias showed coexpression of early B-lymphocyte markers (TdT, HLA-DR, CD19) and myeloid receptors (CD13, CD15, CD33).
• Five cases demonstrated positive esterase staining; four cases had chromosome 11 structural abnormalities, with three showing breaks at 11q23-24.
• Two cases were chronic myelogenous leukemia in blast crisis; all mixed lineage cases behaved aggressively.

Conclusions:

• Mixed lineage leukemias represent an identifiable subset of adult acute leukemias.
• These leukemias are characterized by specific immunophenotypic and cytogenetic findings.
• Mixed lineage leukemias are associated with aggressive clinical behavior and a poor prognosis.