The authors describe a child with clinical presentation of acute leukemia and an immunophenotype consistent with precursor B-cell acute lymphoblastic leukemia. However, the lymphoblasts had atypical L3 features and the chromosome rearrangement t(8;22)(q24.1;q11.2) involving the MYC locus. The cytogenetic features in this patient were characteristic of mature B/Burkitt leukemia and led to modulation of therapy. This case highlights the need for timely cytogenetic and molecular studies in the diagnosis of acute leukemia.