[Mixed myelodysplastic and myeloproliferative syndromes]

An injury to the hemopoietic stem cell may lead to the aplasia of hemopoiesis, myelodysplasia and to an unregulated myeloproliferation. There is not a strict demarcation of them, so that mixed syndromes can develop as are hypoplastic syndromes on one side and mixed myelodysplastic and myeloproliferative syndromes (MDS-MPS) on the other side.

Among our 616 pts with MDS we looked for those cases, who had beside myelodysplasia signs of myeloproliferation with increased number of blood cells. They were examined in detail including bone-marrow histology, bone marrow cultivation, cytogenetics and bcr-abl gen. Signs of MDS-MPS were found in 22 patients at the first contact with the patient (13 patients had thrombocytemia and 9 patients had leukocytosis). Further 7 patients were diagnosed as MDS, proliferative syndrome developed after several months (MDS-MPS in evolution). The level of thrombocytemia was relatively stable, the number of leukocytes was progressive. All subtypes of MDS were found. All subjects had variable degree of anemia. Ring-sideroblasts and myelofibrosis were frequent finding in MDS-MPS. Men prevailed in patients with leukocytosis. Cytogenetic and cultivation findings were similar to MDS cases, deletion of long arm of chromosome 20 was present in 3 patients. Five patients transformed to acute myeloid leukemia.

Sings of myelodysplasia and myeloproliferation were found in 4% of our MDS patients, designated as mixed myelodysplastic and myeloproliferative syndrome (MDS-MPS). In this syndrome beside evident signs of myelodysplasia thrombocythemia or leukocytosis with the release of bone marrow precursors are present. In only one case polycythemia was encountered.