Abstract • 181
At the NCI, Cairo University, ALL constitutes 30% of all pediatric malignancies and 70% of pediatric leukemia. Cases show a male to female ratio of 2.3 : 1. The 2-10 years age group constitutes 68.5%. Clinically hepatosplenomegaly is encountered in 75% of the patients, mediastinal and/or hilar lymphadenopathy in 17% and CNS leukemia at diagnosis in 5.7%. WBC count < 10×109/L is encounterd in 25.7%, 10-50 in 38.1% while ≥ 50 in 37.2% of cases. The FAB subtype distribution includes 33.6% L1, 62.1% L2, and 4.3% L3. Early reports on immunophenotyping showed T cell predominance of >50% with precursor B of 40%. Recently since 1994 a shift was observed with precursor B of about 68% and T ALL of about 30%. With regards to the T-ALL cases, only 34.3% express pure T markers, 19.6% express CD10 as well while 46.1% express both CD19 and CD10. Myeloid marker expression is encountered in 16.8% of our pediatric ALL cases. Gene rearrangement studies showed IgJH rearrangement in 24/24 B lineage and 9/21 T lineage ALL (including 6 T ALL cases expressing CD10 and CD19). TCR gene(s) rearrangement was encountered in 27/27 TALL and 10/24 precursor B ALL.
