ABSTRACT
<p><b>OBJECTIVE</b>To study the clinical characteristics of ecotopic viral integration site-1 (EVI1) and BCR/ABL positive childhood leukemia.</p><p><b>METHODS</b>Clinical data of four children with EVI1 and BCR/ABL positive leukemia and eight children with BCR/ABL positive but EVI1 negative chronic myeloid leukemia (CML) were retrospectively analyzed.</p><p><b>RESULTS</b>In the four children with EVI1 and BCR/ABL positive leukemia, two were initially diagnosed with chronic phase of CML, one with accelerated phase of CML and one with high-risk acute lymphoblastic leukemia (ALL). There were no significant differences in clinical characteristics at diagnosis between the patients with EVI1 and BCR/ABL positive leukemia and BCR/ABL positive but EVI1 negative leukemia. CD33 and CD38 were highly expressed and t(9;22) abnormality was present in all patients with EVI1 and BCR/ABL positive leukemia. Two of the 3 children with EVI1 and BCR/ABL positive CML achieved complete remission one or three months after treatment. Acquired negative status conversion occurred for EVI1 but not BCR/ABL in one CML case. The 3 children with EVI1 and BCR/ABL positive CML survived 20, 13 and 14 months, respectively, without recurrence. The child with EVI1 and BCR/ABL positive ALL failed to achieve complete remission after the first course of treatment and discontinued further treatment.</p><p><b>CONCLUSIONS</b>Co-expression of EVI1 and BCR/ABL fusion gene can be found in childhood CML and ALL. The relatively rare leukemia has not significant difference respect to clinical characteristics. Prognosis of the disease needs to be determined by clinical studies with a larger sample size.</p>