The Role of Immunophenotyping in Diagnosis of Biphenotypic Acute Leukemias

Introduction: The majority of acute leukemias can be classified as myeloid, B, or T lymphoid. In some cases this is not possible because of the evidence of expression of both lymphoid and myeloid lineage-specific antigens in the blast cells. These cases were defined as biphenotypic acute leukemias. The aim of this study was to present the importance of immunophenotyping in diagnosis of biphenotypic acute leukemias.
Material and method: In our report we present 8 cases of biphenotypic acute leukemia from a total of 218 patient diagnosed with acute leukemia. We performed immunophenptyping of bone marrow samples. Three-or four-color immunoflourescence staining was used. The diagnosis was established according to EGIL (European Group for the Immunological Classification of Leukemias) classification.
Results: Immunophenotyping identified 4 cases with B-lymphoid+myeloid immunophenotype, 2 cases had T-lymphoid+myeloid immunophenotype, 1 patient had B+T-lymphoid immunophenotype and 1 patient had biclonal AL. Except one patient, all of them had blasts positive for CD34 marker. 4 of the patients were treated with acute lymphoblastic leukemia protocol, 2 with acute myeloblastic leukemia protocol and 2 cases with acute myeloblastic leukemia protocol after failure of ALL protocol. The outcome was poor, the median survival was 4 months.
Conclusions: Immunophenotyping of blasts cells is indispensable in the diagnosis of biphenotypic acute leukemia. The most common immunophenotype is co-expression of myeloid and B-lymphoid markers and co-expression of myeloid and B-lymphoid markers. Most cases show expression of stem cell marker CD34. The outcome of this type of leukemias are poor.