Down syndrome associated childhood myeloid leukemia with yet unreported acquired chromosomal abnormalities and a new potential adverse marker: dup(1)(q25q44)

Down syndrome presenting with different hematological manifestations: A case series of four cases

Children with Down syndrome (DS) are found to have an increased risk of developing various hematological disorders. Particularly, they have an increased predisposition to acute leukemia, predominantly the myeloid type known as myeloid leukemia of Down syndrome (ML-DS). The major morphological subtype is acute megakaryoblastic leukemia. Approximately 10% of the neonates with DS show a unique disorder known as transient leukemia or transient abnormal myelopoiesis (TAM). Their clinical and morphological features are indistinguishable from acute myeloid leukemia (AML); however, they regress spontaneously within the first few months of life. Here we present a series of four cases with different hematological conditions in children with DS. Of the four cases, two presented with AML-M7, one with TAM, and one case was diagnosed as AML-M2 subtype. This case series highlights the spectrum of hematological disorders in children with DS. Although the majority of the case studies show that TAM and AML-M7 are strongly associated with DS, this case series brings to focus that other AML subtypes may occur as well.

Transient leukemia of Down syndrome

Childhood leukemia is mostly a "developmental accident" during fetal hematopoiesis and may require multiple prenatal and postnatal "hits". The World Health Organization defines transient leukemia of Down syndrome (DS) as increased peripheral blood blasts in neonates with DS and classifies this type of leukemia as a separate entity. Although it was shown that DS predisposes children to myeloid leukemia, neither the nature of the predisposition nor the associated genetic lesions have been defined. Acute myeloid leukemia of DS is a unique disease characterized by a long pre-leukemic, myelodysplastic phase, unusual chromosomal findings and a high cure rate. In the present manuscript, we present a comprehensive review of the literature about clinical and biological findings of transient leukemia of DS (TL-DS) and link them with the genetic discoveries in the field. We address the manuscript to the pediatric generalist and especially to the next generation of pediatric hematologists.