HETEROGENEITY OF CHILDHOOD B-CELL ACUTE LYMPHOBLASTIC LEUKEMIA (EGIL SUBTYPE BIV)

Introduction. Surface immunoglobulin expression is a main immunophenotypic criteria of mature subtype of B-lineage acute lymphoblastic leukemia. Although the majority of such cases represents Burkitt leukemia/lymphoma, it was shown for several times that membrane IgM could be detected in the absence of other mature lymphomas signs.The aim of the study was to evaluate heterogeneity of childhood acute lymphoblastic leukemia (ALL) with surface IgM expression and to assess correspondence of BIV EGIL ALL subtype with Burkitt lymphoma (BL) bone marrow dissemination.Materials and methods. Immunophenotypic, cytomorfologic and genetic data of 54 BIV-ALL cases were analyzed.Results. Among the studied patients 39 had BL, while others belonged to B-cell precursor ALL (BCP-ALL). All BL patients and none of BCP-ALL patients carried C-MYC rearrangement while in BCP-ALL group in 8 cases and in any BL cases KMT2A rearrangements were found. None of BCP-ALL children had L3 morphology according to FAB classification.Conclusions. B-lineage ALL with surface IgM expression is rather heterogeneous group of cases including typical BL and rare cases of BCP-ALL even with KMT2A-rearrangements. Combination of all available diagnostic technologies will allow precise split of these two different disease and select the appropriate treatment scheme