A population-based study of childhood myelodysplastic syndrome in British Columbia, Canada.

Myelodysplastic syndrome (MDS) is considered to be very rare in children. However, the only two published population-based studies reported widely divergent incidence figures. To further explore the epidemiology of childhood MDS and to evaluate the accuracy of cancer registry and treatment trial data, we conducted a population-based study of children aged 0-14 years in British Columbia (BC), Canada, between 1982 and 1996. MDS was diagnosed in 31 cases corresponding to an annual incidence of 3.2 per million children or 6% of all leukaemias, compared with an incidence of 6.0/million for acute myeloid leukaemia (AML), and of 0.5/million for chronic myeloid leukaemia. There was a non-significant (P = 0.19) trend toward an increase in MDS incidence with time, the increase was partly explained by an increasing number of patients with Down syndrome. Associated abnormalities were found in 48% of the MDS cases with Down syndrome as the most common (seven cases). Only one third of the MDS cases were correctly registered in the Cancer Registry and less than half of the eligible MDS patients were enrolled on a cooperative group study. Data on MDS from treatment-based studies and cancer registries were inaccurate and seemed to significantly underestimate the incidence of MDS in children.

Platelet refractoriness and alloimmunization in pediatric oncology and bone marrow transplant patients.

BACKGROUND: The purposes of this study were to determine the overall incidence of platelet refractoriness and alloimmunization among multiply transfused children on a medical oncology and bone marrow transplant service and to evaluate the effect of routine white cell reduction in blood components on that incidence. STUDY DESIGN AND METHODS: The platelet transfusion records of 128 consecutive children admitted to the hospital and requiring blood component support for the treatment of disease were evaluated retrospectively. Mean corrected count increments (CCIs) for each patient were calculated for all random-donor platelet transfusions given within 7 days of the routine weekly testings of the patient's serum for lymphocytotoxic antibodies (LCTAbs). Mean CCIs for HLA-matched platelet transfusions were calculated separately for the patients receiving them. RESULTS: Thirty-one patients (24%) had or developed persistently positive LCTAbs (patient's serum reacted with > or = 3/10 panel lymphocytes); 22 (71%) of these patients had a mean CCI < 7.5 to random-donor platelet transfusions. In contrast, of the 97 patients with negative or transiently positive LCTAbs, only 25 (26%) had a mean CCI < 7.5. The overall incidence of platelet refractoriness (CCI < 7.5) was 37 percent. Patients with acute myelogenous leukemia had a significantly (p < 0.01) reduced incidence (17%) of low CCIs, with or without positive LCTAbs, as compared to patients with other malignant or nonmalignant disorders (41%). No difference in the incidence of LCTAbs or low CCIs was seen in patients undergoing allogeneic or autologous bone marrow transplant or receiving drug therapy only. Among the 24 patients who received HLA-matched platelets, only those with positive LCTAbs showed a significant improvement in CCIs over that achieved with random-donor platelet transfusions. Routine white cell reduction in red cell and platelet components with third-generation white cell filters was performed prior to transfusion in 73 of the patients. There was no significant difference between the incidence of LCTAbs and/or low CCIs in this group and that in the 55 children receiving unfiltered transfusions. CONCLUSION: Alloimmunization and platelet refractoriness occur in pediatric oncology and bone marrow transplant patients, but the incidence--particularly in children with acute myelogenous leukemia--appears to be low. The detection of LCTAbs predicts a poor response to random-donor platelet transfusion, but most such patients show improved CCIs with HLA-matched platelets. Routine use of white cell-reduction filters has thus far failed to eliminate alloimmunization in children requiring prolonged blood component support.

Childhood myelodysplasia: suggested classification as myelodysplastic syndromes based on laboratory and clinical findings.

Fourteen children with a primary myelodysplastic syndrome (MDS) were seen at this center over a 10-year period. Six of the patients, including two pairs of siblings, had a monosomy 7 population in their bone marrow. Seven patients had the clinical and laboratory features of "juvenile chronic myeloid leukemia." Three patients could be considered to have either the monosomy 7 syndrome or "juvenile chronic myeloid leukemia," indicating that these two entities are not mutually exclusive. All patients fulfilled the French-American-British (FAB) criteria for a myelodysplastic syndrome. Clonal chromosomal abnormalities were detected in 13 of the 14 patients, and consistently involved either monosomy 7, multiple abnormalities, and/or multiple clones. Hematopoietic progenitor assays of blood and marrow samples obtained from most patients showed abnormal progenitor frequencies, or differentiation patterns in culture (or both), often affecting the erythroid as well as the granulopoietic lineages. In particular, granulopoietic progenitors from four to six patients in the "juvenile chronic myeloid leukemia" category generated predominantly abnormal appearing macrophage colonies. Clinical outcomes were poor with rapid transformation to acute myeloid leukemia in most patients. All treated patients responded poorly to conventional chemotherapy, although in two cases remission was achieved with intensive therapy and allogeneic bone marrow transplantation. Childhood myelodysplasia includes a group of diseases that are clinically heterogeneous, and current terminology is confused and inconsistent. Until a better understanding of the biologic and molecular basis of these diseases is obtained, it is proposed that the use of the FAB categories developed for adult MDS might help to improve diagnostic precision and therapeutic comparisons.

Congenital erythroleukemia: a case report with morphological, immunophenotypic, and cytogenetic findings.

We report a lethal case of congenital erythroleukemia presenting on the first day of life with peripheral blast cells and a leukemic infiltrate in the placenta. Although initial bone marrow examination did not fulfill the French-American-British (FAB) cooperative group criteria for acute myelogenous leukemia (AML), including M6, a malignant clone was confirmed by cytogenetic analysis: 49,XX, +8, +19, +21. Evolution to erythroleukemia (M6) occurred over a two-month period. The diagnosis of erythroleukemia was supported by immunophenotyping employing an antibody to glycophorin A. The clinical course was complicated by liver failure of unknown etiology. Comparison to previously reported cases of early childhood erythroleukemia is made.

Unbalanced translocation (1;7) in childhood myelodysplasia.

We have identified an unusual pediatric patient among twelve patients with myelodysplasia and an unbalanced translocation involving chromosomes 1 and 7: -7, +der(1)t(1;7)(p11;p11). This 16-year-old male patient developed myelodysplasia and evolving acute leukemia, which were preceded by a 7-year history of marrow hypoplasia. The remaining patients were adults with clinical and hematologic findings similar to other reported cases with this chromosomal abnormality. The late appearance of this unbalanced clonal abnormality in this patient with marrow hypoplasia documents the importance of close cytogenetic follow-up of all patients with suspected bone marrow injury.