The preleukemic syndromes (hematopoietic dysplasia) in childhood.

The preleukemic syndrome or hematopoietic dysplasia is a marrow stem-cell disorder with clinically recognizable hematologic abnormalities which precede the development of acute nonlymphocytic leukemia. Its occurrence in childhood is extremely rare; seven "true" cases who fulfill all the criteria for the disorder have been reported until now. The preleukemic syndrome is generally characterized by peripheral cytopenia with fairly specific morphologic abnormalities in cell differentiation. The hematological and clinical features permit recognition of preleukemia even before the development of overt leukemia. Experimental data indicate that preleukemia is an "early" leukemic syndrome in which hematopoietic cell differentiation becomes progressively impaired with termination in the nearly complete maturation block which is characteristic of acute myelogenous leukemia.