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Clinical characteristics and outcome of biphenotypic acute leukemia in children

King Faisal Specialist Hospital and Research Center

Correspondence: Amal S Al-Seraihy, Deprtment of Pediatric Hematology-Oncology, King Faisal Specialist Hospital and Research Center, PO BOX 3354, Riyadh 11211 MBC 53, Saudi Arabia. E-mail:aseraihy{at}kfshrc.edu.sa

ABSTRACT

Background: Knowledge about Biphenotypic acute leukemia (BAL) in children is limited, both in terms of clinical and biological presentation and also with regard to treatment outcome

Design and Methods: This retrospective review analyzes the clinical features and the outcome of BAL in children diagnosed and treated over eight years. According to EGIL scoring system 24 cases (3.7 % of 633 patients with acute leukemia) were classified as BAL. The diagnostic workup and results were reviewed specifically for this study in light of the newly published WHO criteria for diagnosis of leukemia of ambiguous lineage. Based on these criteria 11 (1.7%) patients were categorized according to the new nomenclature as mixed phenotype acute leukemia (MPAL). The majority of the patients (58.3%) had a B-lymphoid/myeloid phenotype followed by the T-lymphoid/myeloid phenotype. The most frequent chromosomal abnormality involved the 14q32 locus. Patients received therapy based on an ALL regimen, which included myeloid-effective agents.

Results: At a median follow up of 4 years (range 6 month – 7 years) the OS was 75.7% and EFS was 73.5%. The survival for those patients who received HSCT in first CR was no different from those patients who were treated with chemotherapy alone (OS 70.1% versus 81.1%, p=0.39; EFS 70.1% versus 76.2%, p=0.75). The survival outcome for the 11 patients who were retrospectively classified as MPAL according to the new WHO criteria was excellent, with no relapses or deaths.

Conclusions: An ALL type of induction utilizing agents that have activity against lymphoid and myeloid leukemias appears to be more effective in achieving and maintaining CR whether the patients are classified according to EGIL or the new WHO criteria. HSCT may not be necessary for all patients in first CR.

Key words: biphenotypic acute leukemia, diagnosis, therapy, immunophenotyping, stem cell transplant.