Background: Acute lymphoblastic leukemia (ALL) is the most common cancer in the pediatric population. With modern treatments, the chance of the complete recovery is nearly 100%. The most important prognostic factors are appropriate treatment protocol and determination of patient risk factors based on clinical, morphological, immunological and cytological characteristics. In this study we reviewed frequency of these factors, like as age, gender, the primary white blood cell number, sub- group on the base of FAB classification, immunophenotype and the clinical progress.

Methods: In this retrospective study, we reviewed 877 pediatric patients with the diagnosis of ALL between the years of 1994 and 2004. In these patients the age, gender, primary WBC count, sub-group based on the FAB classification, immunophenotype and the clinical progress in 177 patient with acute lymphoblastic leukemia at Imam Khomeini Hospital between the years of 1994 to 2004 were determined.

Results: Of these patients, 1.6% was younger than one year, 24.8% more than ten years old and 73.6% were between the ages of one and ten years; 63.8% were male. WBC counts were above 50,000/ul in 28.8% of the patients. FAB classifications included L1 in 80.2%, L2 in 17.5% and L3 in 2.3% of the patients. Immunophenotypes included pre-B cell in 63.8%, early pre-B cell in 23.1%, T cell in 12.3% and mature B cell in 0.8% of the patients. Marker CD10+ was detected in 88.1% of the B cell cases. In this study group, 74% of the patients recovered, 16.3% died and 16.5% relapsed.

Conclusions: The prevalence of FAB-L1 and pre-B cell cases in this study is greater than a previous study, while the prevalence of FAB-L2 and early pre-B cell cases is less than that of the previous study.