RESUMO
T-cell acute lymphoblastic leukemia (T-ALL) may affect children in very early age. However, the critical events leading to this brief latency is still unclear. We used standard methods to explore NOTCH1 mutations and other specific molecular markers in 15 early childhood T-ALL cases. Most of them consisted of immature differentiation subtype. Despite being found in a lower frequency than that described for overall pediatric T-ALL, NOTCH1 alterations were the most frequent ones. Other alterations included MLL(+) (n=4), SIL-TAL1(+) (n=3), FLT3 mutation (n=1) and HOX11L2(+) (n=1). Our results suggest that NOTCH1 and MLL abnormalities are primary leukemogenic hits in early T-ALL.
Assuntos
Mutação , Proteína de Leucina Linfoide-Mieloide/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Receptor Notch1/genética , Transformação Celular Neoplásica/genética , Pré-Escolar , Aberrações Cromossômicas , Feminino , Rearranjo Gênico/fisiologia , Genes Codificadores da Cadeia delta de Receptores de Linfócitos T , Genes Codificadores da Cadeia gama de Receptores de Linfócitos T , Testes Genéticos , Histona-Lisina N-Metiltransferase , Humanos , Lactente , Masculino , Mutação/fisiologiaRESUMO
The leptomeningeal involvement of central nervous system is defined in the most centers by the presence of blast cells in the CSF or the presence of cranial-nerve palsies. Sometimes, cytology does not allow clear distinction between lymphoblasts and normal cells, and auxiliary methods to the precise identification of leukemic cells in cerebrospinal fluid is necessary. We analyzed CSF from 11 consecutive patients, in whom a differential diagnosis of leptomeningeal involvement was made, including 4 patients at diagnosis and 7 patients during the treatment by cytomorphological analysis and PCR and automatic sequencing. Six patients were considered with leptomeningeal involvement by conventional analysis: unequivocal cytomorphological involvement was considered in 5 patients, and in one it was assumed to be due to cranial-nerve palsy, with no blast cells detected in cerebrospinal fluid. In 2 it was considered suspicious and in 3 negative. PCR and sequencing analysis showed involvement in 6 patients; 5 of the 6 patients were considered to have leptomeningeal involvement based on clinical and cytomorphological criteria, and, in one of the patients, it was suspicious. Our data suggest that the use of PCR and sequencing can be useful in confirming CNS leukemia and eliminating other conditions when used together with the cytomorphological analysis.
Assuntos
Líquido Cefalorraquidiano/citologia , Citodiagnóstico/métodos , Neoplasias Meníngeas/líquido cefalorraquidiano , Meninges/patologia , Reação em Cadeia da Polimerase/métodos , Leucemia-Linfoma Linfoblástico de Células Precursoras/líquido cefalorraquidiano , Células da Medula Óssea/química , Células da Medula Óssea/patologia , Criança , Células Clonais/patologia , DNA de Neoplasias/líquido cefalorraquidiano , Rearranjo Gênico da Cadeia delta dos Receptores de Antígenos dos Linfócitos T/genética , Rearranjo Gênico da Cadeia gama dos Receptores de Antígenos dos Linfócitos T/genética , Genes Codificadores da Cadeia delta de Receptores de Linfócitos T/genética , Genes Codificadores da Cadeia gama de Receptores de Linfócitos T/genética , Humanos , Cadeias Pesadas de Imunoglobulinas/genética , Neoplasias Meníngeas/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Reprodutibilidade dos TestesRESUMO
BACKGROUND: The initial response to induction therapy is currently considered one of the most important prognostic factors in acute lymphoblastic leukemias (ALL). A series of methods for the detection of submicroscopic levels of residual disease in patients with ALL mainly based on PCR and immunophenotyping has been developed, demonstrating that the presence of high levels of residual disease at the end of induction therapy is an important, independent prognostic factor. We determined the usefulness of PCR detection of minimal residual disease using consensus primers as a non-remission criterion. PROCEDURE: Bone marrow samples obtained from 49 children with ALL were analyzed at diagnosis and at the end of induction therapy for the detection of clonal IgH, TCRdelta, and TCRgamma rearrangements by PCR. The results were compared with those obtained by standard morphologic analysis and risk group classification. RESULTS: Patients who had clonality detected at the end of induction showed a significantly higher recurrence rate and lower event-free survival than those without detected clonality (24.9% vs. 89.7%) (P < 0.0001). Multivariate analysis revealed that detection of clonality at the end of induction was the most important, independent prognostic factor when associated with age, number of white blood cells, and immunophenotyping. CONCLUSIONS: PCR detection of clonality using consensus primers is a relatively simple technique that is able to identify patients with a high chance of recurrence, and shows a higher sensitivity and a better prognostic value than standard morphologic analysis and risk group classification, defining a new remission criterion. However, further multicentric prospective studies using this technique employing a larger number of cases are necessary to confirm these findings.