Burkitt lymphoma/leukaemia transformed from a precursor B cell: clinical and molecular aspects.

Burkitt lymphoma/leukaemia (BL/L) is a heterogeneous disease with respect to epidemiological patterns and cell origin. The occurrence of BL/L with an immature phenotype raises the question whether this phenotype might be a consequence of early B-cell transformation or, alternatively, a secondary feature of transformed, mature B cells. It also poses important clinical questions regarding diagnosis and therapeutic procedures. Here we describe the case of a 4-yr-old child with BL/L and FAB L3 morphology, with phenotypic and genotypic characteristics of a CD10+ precursor B-cell acute lymphoid leukaemia (ALL) associated with t(8;14)(q24;q32). Molecular analysis showed expression of RAG1 and RAG2 and an unmutated VDJCmu immunoglobulin rearrangement coinciding with a lack of AICDA expression, indicating an immature B-cell origin. His clinical response suggested that FAB L3 ALL with MYC rearrangement and an aberrant precursor B-cell phenotype is clinically similar to BL/L. Moreover, short, intensive chemotherapeutic protocols seemed to be beneficial. This case also allowed us to refine the description of cellular and molecular variants of BL/L regarding the cell origin and pathogenesis of this biologically heterogeneous disease.