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Biphenotypic acute leukemia in adults
L E Sulak1, C N Clare, B A Morale
1Department of Pathology, University of Texas Health Science Center, San Antonio 78284.
Insights
Mixed lineage leukemias, identified by coexpressed B-lymphocyte and myeloid markers, are an aggressive subset of adult acute leukemias. These cases, often linked to chromosome 11 abnormalities, indicate a poor prognosis.
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.
Abstract:
Leukemias are characterized by an idiopathic proliferation of a progenitor cell that is committed to a single cell lineage. However, leukemias with dual-lineage differentiation are being described, especially within the pediatric age group. The authors reviewed 118 cases of adult acute leukemia phenotyped by immunofluorescent flow cytometry; 7 cases demonstrated mixed cell lineage. Immunophenotypically these cases were defined by early B-lymphocyte differentiation (TdT, HLA-DR, and CD19) coexpressed with a myeloid receptor (CD13, CD15, or CD33) on the same leukemic cell. Routine cytochemical evaluation demonstrated punctate positivity of the blasts with naphthol AS-D chloroacetate esterase stain in five of seven cases. Cytogenetic analysis revealed structural abnormalities of chromosome 11 in four of the seven cases. Three of these studies showed a break at 11q23-24, the location of the human proto-oncogene ets-1. Clinically, two of these leukemias represented chronic myelogenous leukemia in blast crisis, and all cases behaved aggressively. The authors' data suggest that mixed lineage leukemias are an identifiable subset of adult acute leukemias and are associated with a poor prognosis.