MIXED MYELODYSPLASTIC AND MYELOPROLIFERATIVE SYNDROMES

Aplastic anemia, myelodysplastic syndromes (MDS) and chronic myeloprol iferative diseases (MPD) are stem cell disorders. There is no clear-cu t demarcation of them. Hypoplastic MDS displays features of aplastic a nemia and MDS, on the other side mixed myelodysplastic and myeloprolif erative syndromes (MDS-MPS) develop. In our collection of 566 MDS pati ents, features of myelodysplasia as well as myeloproliferation, MDS-MP S, were present in 25 patients (4.4%). Twelve patients had at the time of diagnosis megakaryocytic proliferation and thrombocythemia beside signs of MDS, and seven had myelodysplasia with granulocytic prolifera tion and leukocytosis. In another six patients, MDS was the first diag nosis and the proliferative phase developed later during the course of the disease. These patients can be characterized as MDS-MPS in evolut ion. All subjects had a variable degree of anemia. While the level of thrombocythemia has been relatively stable, the number of leukocytes h as been progressive, but rarely extended beyond 100 x 10(9)/l. Ring-si deroblasts and myelofibrosis were frequent findings. Two more homogene ous MDS-MPS groups emerged in our analysis: sideroblastic anemia with thrombocythemia and a group fulfilling the criteria of Philadelphia ch romosome negative and bcr-abl negative 'atypical chronic myeloid leuke mia (aCML)'. One patient with thrombocythemia and three with leukocyto sis (23%) transformed to acute myeloid leukemia (AML). Men prevailed ( 12/13) in patients with leukocytosis and MDS-MPS in evolution. Of the 46% MDS-MPS patients with chromosomal aberrations, del(20)(q) is of in terest. Copyright (C) 1996 Elsevier Science Ltd