Clinical Characteristics of Biphenotypic Acute Leukemia in Childhood: A Single Institutional Experience / 대한소아혈액종양학회지

ABSTRACT

PURPOSE: The diagnostic criteria of the biphenotypic acute leukemia (BAL) are based on the number and degree of the specificity of the immunological markers expressed on the leukemic blasts. The newer diagnostic criteria proposed by The European Group for the Immunological Classification of Leukaemias (EGIL) is now well accepted. We have recently evaluated our BAL patients using the EGIL criteria and analyzed the clinical characteristics, treatment and clinical outcome. METHODS: Fourteen children diagnosed with BAL among 193 childhood acute leukemia patients in our hospital from January 1995 to December 2001 were retrospectively reviewed. RESULTS: The incidence of BAL was 7.3% (14 out of 193 cases). Of these 14 patients, 12 were de novo and 2 were secondary. In the de novo group, the immunological marker studies showed myeloid/B-lymphoid phenotype in 6 (50%), myeloid/T-lymphoid in 3 and B-lymphoid/T-lymphoid in 1. In addition, two patients showed trilineage differentiation. Cytogenetic analysis revealed various abnormal karyotypes in the majority of the cases, showing normal karyotype only in 3 cases. Among the karyotype abnormalities, two were t (9; 22) and one was t (4; 11). Chemotherapy was mostly based on the induction regimen of acute lymphoblastic leukemia therapy (12 of 14 cases). One patient was treated with acute myeloid leukemia regimen and one patient received combination of both acute lymphoid and myeloid regimen. Induction of complete remission was achieved in 100% of the patients and the median duration of induction therapy to complete remission was 33 days. Five of the 12 de novo patients died during the median follow-up of 16.5 months (4 months to 37.5 months) and the 2 year survival rate was only 52%. CONCLUSION: The incidence of BAL in children is relatively rare and the most common immunophenotypic expression consists of myeloid and B-lymphoid coexpression. Most of the cases showed chromosomal abnormalities. The outcome of BAL treated mostly with the traditional acute lymphoblastic leukemia induc without stem cell transplantation should be sought especially in those expressing poor prognostic cytogenetic abnormalities or strong myeloid marker expression.