TdT-Positive, SmIg-Negative B Precursor Cell Leukemia with Burkitt Morphology: A Case Report

The phenotypic marker profile and molecular analysis of ALL with typical FAB-L3 morphology of a 66-year-old lady are described. We detected the phenotypic expression of B cell-associated antigens (B4, BA1, HLA-DR) and terminal deoxynucleotidyl transferase, but not of surface and cytoplasmic immunoglobulin or cALLA antigen. Molecular analysis revealed that immunoglobulin heavy chain gene was in the rearranged form and that T cell β-receptor gene was in the germ-line form Cytomorphology, immunophenotype and genotype indicated that her leukemic cells had characteristics of B-cell precursor ALL of Burkitt type. Cytogenetic investigation showed a normal karyotype, and neither rearrangement nor amplification of c-myc gene was detected To the best of our knowledge this type of TdT-positive, Smlg-negative FAB-L3 with immunological and molecular confirmation has as yet not been reported.