Myelodysplastic Syndromes:Preleukemic or Early Leukemic Conditions?

Abstract

Myelodysplastic syndromes (MDSs) comprise a heterogeneous group of homopoietic disorders sharing some probability of developing into overt leukemia [1]. According to glucose-6-phosphate dehydrogenase [9, 10], restriction fragment length polymorphism [6], and ras point mutation studies [7, 8], there is at least a subgroup of MDSs showing clonal growth of bone marrow cells. Up to now, however, it has been impossible to state that clonal cell growth is equivalent to malignant growth. It is conceivable that the progeny of an altered stem cell possesses some growth advantage over nonaltered cell populations but nevertheless remains subject to the regulation of steady state between growth and maturation. This regulation may be operating at an altered growth-to-maturation level. On the other hand, if preleukemia is a slowly progressing disorder, the very faint exponential character of the initial blast cell expansion may not become recognizable by standard laboratory examinations.