Correlation of karyotype and immunophenotype in childhood acute lymphoblastic leukemia : experience at the National Cancer Institute, Cairo University, Egypt

Purpose : To identify chromosomal pattern among the major immunophenotypic subgroups in Egyptian children with ALL, and its correlation with clinical presentation and disease free survival. Patients and Methods: Cytogenetic and immunophenotypic analysis were done for all patients. Patients received ALL-PNCI-III/98 chemotherapy protocol used at NCI, Cairo University. Results: The frequency of pseudodiploidy and normal karyotype in the whole group was 42.9% and 33.3% respectively. The frequency of pseudodiploidy was 36.8% in CALLA positive early pre B, 30.7% in pre B cases, 71.4% in T cell cases and 100% in mature B cell cases. At 12 months, DFS was 50% for pseudodiploid group having pre B phenotype, compared to 16.6% for pseudodiploid group with CALLA positive early pre B ALL. Sixteen percent of the studied cases showed T cell phenotype, 71.4% of them showed pseudodiploid karyotype, all of them had high risk features. Hyperdiploidy was found in 31.5% of CALLA positive early pre B cases and was associated with favorable prognostic features and DFS of 66.6% at 12 months. Hyperdiploidy of >50 chromosome represented 62.5% of hyperdipoid cases, 80% of them were CALLA positive early pre B ALL carrying good risk features. Fifty percent of normal karyotypic patients showed pre B phenotype, while 42.8% showed CALLA positive early pre B ALL. Their age, TLC, DFS, were almost comparable. Conclusion: CALLA early pre B phenotype has a positive impact on chromosomal pattern having best outcome among patients with hyperdiploidy. The Pseudodiploid karyotype carries a better outcome with pre B phenotype.