Preleukemic state preceding adult acute lymphoblastic leukemia

Abstract

A cute lymphoblastic leukemia (ALL) in adults typically presents fulminantly. However, there are numerous examples in the literature where ALL developed from an antecedent hematologic disorder. These preceding disorders include chronic granulocytic leukemia [1,2], polycythemia vera [3], the myelodysplastic syndromes [4-15], chronic lymphocytic leukemia [16-18], paroxysmal nocturnal hemoglobinuria [19], apparent aplastic anemia in children [20-27] or young adults [28-30], and isolated neutropenia [31,32] or erythroid hypoplasia [33]. These cases are characterized by a lack of morphologically distinguishable lymphoblasts during the phase. There is one case report of a 12-year-old patient with ALL who presented with a syndrome that resembled aplastic anemia and who demonstrated an increased number of CALLA (common acute lymphocytic leukemia antigen)-positive cells in the initial bone marrow. However, the authors were unable to clearly identify lymphoblasts in the bone marrow specimen [20]. Myelodysplasia (MDS) classically encompasses a group of disorders with a relatively high propensity to progress to acute myelogenous leukemia. However, occasional case reports clearly demonstrate that MDS also has the potential to progress to ALL [4-11] or biphenotypic leukemia [12-15]. All these cases showed obvious multilineage maturation abnormalities and no evidence of increased numbers of lymphoblasts prior to acute transformation. In this article, we report data on two patients with adult ALL who presented with an extended preleukemic phase ultimately terminating in overt ALL after several months. These patients differed somewhat in their presentation, yet both were characterized by leukopenia. No morphologic abnormalities were found in any lineage other than the lymphocytic lineage. From the outset, there was ev-