RESUMO
INTRODUCTION: In B-cell acute lymphoblastic leukemia (B-ALL), testing at diagnosis for BCR/ABL1 gene rearrangements is mandatory for prognostic stratification and treatment decisions. Several diagnostic methods have been proposed using flow cytometry to identify BCR/ABL1(+) B-ALL. METHODS: We evaluated expression of the myeloid antigen CD66c by flow cytometry in B-ALL. We studied 94 patients with B-ALL. The t(9;22)(q34;q11) or BCR/ABL1 rearrangement was detected by cytogenetic analysis or RT/PCR. Myeloid antigens CD66c, CD13, CD33, CD117, Myeloperoxidase, CD15 and CD65 were determined by flow cytometry. RESULTS: Of these 94 cases, 17 (18%) cases displayed BCR/ABL1 gene rearrangements and 38 (40%) cases were CD66c positive. CD66c was the most common myeloid antigen expressed on malignant lymphoblasts. Its expression was correlated with BCR/ABL1 rearrangements (P = 0.0001): sensitivity 82%, specificity 69%, positive predictive value 37% and negative predictive value 95%. Co-expression of CD66c(+) CD13(+) was more frequent in BCR/ABL1(+) B-ALL (29%) than BCR/ABL1(-) cases (4%) (P = 0.0044). Some BCR/ABL1(-) B-ALL cases (including hyperdiploid or cases with normal karyotype) were CD66c positive (31%). CONCLUSION: CD66c expression is correlated, but not specifically, with BCR/ABL1 rearrangement. It would seem better to interpret the absence of CD66c expression with a lack of BCR/ABL1 rearrangement. This myeloid antigen could be interesting in the detection of minimal residual disease.
Assuntos
Antígenos CD/genética , Antígenos CD/metabolismo , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Regulação Neoplásica da Expressão Gênica , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Proteínas Ligadas por GPI/genética , Proteínas Ligadas por GPI/metabolismo , Rearranjo Gênico/genética , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasia Residual/genética , Adulto JovemRESUMO
Biphenotypic acute leukaemia (BAL) represents about 5% of adult acute leukaemia. Based on a previously described scoring system, the European Group for Immunologic Classification of Leukaemia (EGIL) proposed a set of diagnostic criteria for BAL. This scoring system is based on the number and degree of the specificity of several markers for myeloid or T/B lymphoid blasts. Here, we report the case of a BAL with Burkitt-like cytology, corresponding to "the acute lymphoblastic leukaemia, Burkitt type" L3 for the FAB classification. By flow cytometry, the blasts showed a positivity for B lymphoid cytoplasmic (CD79a and mu) and membrane (CD19, CD22, CD24, IgM) markers AND a positivity for the myeloid (CD13, CD33, CD65, CD15) markers.