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Background: : We analyzed effects of exposure to magnetic fields on the expression of acute leukemia in children with Down syndrome (who have a 20-fold higher risk of leukemia)., Methods: : We performed a case-control study that included 42 children with both acute leukemia and Down syndrome as cases and 124 healthy children with Down syndrome as controls. We obtained demographic information concerning the children and took spot measurements of magnetic fields at each residence., Results: : The odds ratio for direct measurements of magnetic fields >/=6.00 mG was 3.7 (95% confidence interval = 1.05-13.1)., Conclusion: : The association between magnetic fields and leukemia in children with Down syndrome suggests the possibility of a causal role for magnetic fields in the etiology of leukemia among a genetically susceptible subgroup of children.

To assess the incidence, clinical features at presentation, hematologic, immunophenotypic, and cytogenetic characteristics of AMKL in children we prospectively studied 834 consecutive non selected children with newly diagnosed acute leukemia (AL) admitted to the Hematology Department at the Instituto Nacional de Pediatría (INP), Mexico, D.F. We found 682 cases (81.8%) with a typical ALL immunophenotype, and the remaining 152 (18.2%) were considered to have AML. In 29 of the 152 patients with AML studied, a diagnosis of AMKL was established. These 29 cases represented 19.1% of the cases of AML and 3.48% of the total cases of AL during the time span covered by the study. Twenty-four percent of the cases occurred in infants 2 years old or younger and 41.4% occurred in children 41 months of age or younger. In contrast, in only 18.6% of the patients with AML (M0-M6), the diagnosis was established before 42 months of age and in 17% before their second year of life. Clinical presentation was not strikingly different than that observed in patients with other types of AML, and the time interval from onset of symptoms to diagnosis was also similar, though in a small subset of patients, the clinical course was characterized by a chronic slowly progressive disorder extending over weeks or months resembling smoldering leukemia or chronic myelofibrosis with agnogenic myeloid metaplasia. Bone marrow (BM) fibrosis was a constant features in our patients; 75% of the patients studied showed this complication at the time of diagnosis. Some rather unusual findings in this study were intense skeletal pains from multiple osteolytic lesions, the presence of soft-tissue tumor, and the presence of cohesive scanty clusters of primitive-looking blast cells in BM aspirates. Several interesting cytogenetic findings in our study were t(1;22)(p13;q13) in a 14-year-old boy, t(9;22)(q34;q11) in one patient, and monosomy 7 in two patients. Another important finding in our study was the clinical association with colonic adenocarcinoma in one patient, an association that to our knowledge has not been reported previously. In conclusion, our data suggest that the incidence of AMKL in Mexico might be higher than those reported in Caucasian white pediatric population, and that biologic and cytogenetic profile may differ from those of western countries, but more studies are needed to corroborate cytogenetic heterogeneity, ethnic and geographic diversity. Early onset of the disease, low WBC counts, slight thrombocytopenia or normal platelet counts, and BM fibrosis were characteristic distinctive features of at least half of the patients with this subtype of AML., (Copyright 2003 Wiley-Liss, Inc.)

To evaluate the usefulness of flow cytometric detection of intracellular antigens (Ags) in establishing proper lineage affiliation and its contribution to the diagnosis of acute leukemia, we studied 100 consecutive patients in whom acute leukemia was diagnosed between January 1997 and July 1998. Immunological classification was assessed using a three-line panel of monoclonal antibodies for phenotypic characterization of leukemic blast cells as proposed at the First Latin American Consensus Conference for Flow Cytometric Immunophenotyping of Leukemia. We found 74 cases of B-cell lineage acute lymphoblastic leukemia (ALL), seven cases of T-cell ALL, and 19 cases of acute myeloid leukemia (AML). In this study cytoplasmic (cy) CD79a, cyCD22, cyCD3, and cyMPO were highly sensitive, specific B, T, and myeloid markers that were expressed in virtually all cases of B and T cell ALL and in all subtypes of AML. Applied in combination with immunophenotyping this knowledge led to improvement in diagnostic precision and refinement of immunological classification, ensuring the selection of the most appropriate therapy for the patients studied. In conclusion, intracellular Ags detection was of utmost importance in establishing correct lineage affiliation in cases lacking expression of B, T, or myeloid surface Ags or disclosing equivocal or ambiguous immunophenotypic features and in identifying biphenotypic acute leukemia. In combination with FAB morphology and immunophenotyping, we were able to reliably classify all patients with acute leukemia in this study., (Copyright 2001 Wiley-Liss, Inc.)