The value of anti-Pax-5 immunostaining in pediatric acute leukemia

Background Pax-5 protein is a transcription factor expressed in the B-lymphoid lineage from the earliest detectable precursor to the mature B-cell stage. Its expression is closely correlated with B-cell precursor acute lymphoblastic leukemia (pre-B-ALL), which is one of the most common childhood malignancies. Aim of the work To evaluate the expression of anti-Pax-5 monoclonal antibody on leukemic blasts in pediatric patients with acute leukemia and to compare it with anti-CD20 to show its diagnostic utility. Patients and methods This study was carried out on 35 pediatric patients diagnosed with acute leukemia, who were divided into two groups: Pre-B-ALL and Acute, myeloid leukemia (AML). All patients were subjected to a complete assessment of history, full clinical and laboratory examination, bone marrow aspirate and biopsy, and immunophenotyping. Immunostaining of bone marrow trephine biopsy specimens using Pax-5 and CD20 monoclonals was carried out for all cases. Results Pax-5 was positive in 79.1% of cases in the pre-B-ALL group and negative in all AML patients. CD20 was positive in 37.5 and 18% of cases in the ALL and the AML groups, respectively. Pax-5 appeared to be more sensitive (79.2%) and more specific (100%) than CD20 in differentiating ALL and AML. Conclusion Our results highlight the beneficial role of including Pax-5 in an immunohistochemical panel to diagnose acute leukemia of B-cell lineage.