RESUMO
Congenital acute leukemia is a rare form of childhood leukemia, in which lineage conversion at relapse is very rarely reported. Here we describe a case of congenital B-cell acute lymphoblastic leukemia (B-ALL) with t(4;11) and t(1;6) translocations, which at relapse underwent a switch to monocytic lineage with persistence of the original cytogenetic translocations and clonal rearrangement of the JH gene. Similar to the other described cases of congenital acute leukemia with lineage conversion, our case had a MLL gene rearrangement and followed an aggressive clinical course.
Assuntos
Linfoma de Burkitt/genética , Leucemia Mieloide Aguda/genética , Proteína de Leucina Linfoide-Mieloide/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Translocação Genética , Linfoma de Burkitt/congênito , Linfoma de Burkitt/diagnóstico , Linhagem da Célula , Cromossomos Humanos Par 1/genética , Cromossomos Humanos Par 11/genética , Cromossomos Humanos Par 4/genética , Cromossomos Humanos Par 6/genética , Análise Citogenética , Progressão da Doença , Evolução Fatal , Feminino , Histona-Lisina N-Metiltransferase , Humanos , Cadeias Pesadas de Imunoglobulinas/genética , Cadeias J de Imunoglobulina/genética , Imunofenotipagem , Recém-Nascido , Leucemia Mieloide Aguda/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/congênito , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Prognóstico , RecidivaRESUMO
Mature B-cell acute lymphoblastic leukemia (ALL) is typically associated with the FAB-L3 morphology and rearrangement of the MYC gene, features characteristic of the leukemic phase of Burkitt's lymphoma. However, the term 'mature' has also been used to describe other rare cases of B-ALL with light-chain surface immunoglobulin expression. In contrast, infantile B-cell ALL is generally characterized by rearrangement of the MLL gene, an immature pro-B-cell phenotype, and CD10 negativity. We describe two unusual cases of infantile B-ALL with non-L3 morphology, expressing a mature B-cell phenotype (lambda sIg+, CD19+, CD10-, TdT-, and CD34-), and showing MLL rearrangement without MYC rearrangement at presentation. Both infants relapsed after months of morphologic and genetic remission. At relapse, the t(9;11) translocation was detected in both cases by spectral karyotyping. After the initial relapse, both cases followed a rapid and aggressive course. Literature search identified few similar cases, all expressed lambda surface immunoglobulin and showed MLL rearrangement (majority with the t(9;11) translocation). These cases show that B-ALL with MLL rearrangement, especially the t(9;11) translocation, can express a 'mature' B-cell phenotype and may represent a distinct subset. Identification of additional cases will further clarify the significance of MLL rearrangements in mature B-ALL.