Mixed myelodysplastic and myeloproliferative syndromes (MDS-MPS), a new stem cell disorder.

R.Neuwirtová MD PhD a, K.Michalová PhD b, B.Novotná PhD c

a 1st Med.Clin. Dept.Clin.Hematol. Charles Univ.Hospital, Prague, Czech Republic b 3rd Med.Clin. Dept.Cytogenetics Charles Univ.Hospital, Prague, Czech Republic c Inst.Exper.Medicine Academy Sci, Prague, Czech Republic

AIM: The study should contribute to the diagnosis and classification of overlap cases with myelodysplastic and myeloproliferative features. PATIENTS AND METHODS: MDS-MPS patients (pts) have symptoms of MDS including refractory anemia but instead of further peripheral cytopenia they have an increased number of leukocytes, thrombocytes or both. Clinical as well as laboratory data of pts with a special attention to cytogenetics and apoptosis (comet test) of hemopoietic cells were analysed. RESULTS: Among our 1349 MDS pts we found 73 (5.4%) pts fullfilling the diagnosis of MDS-MPS, which was stated either at the first contact with the patient (45pts) or pts are coming as typical MDS and later develop symptoms of MPS. We suggest following classification: (A) relatively benign group of pts with thrombocytosis or thrombocytosis and leukocytosis (B) pts with granulocytic proliferation (with poor prognosis): a) Ph and bcr-abl negative chronic myeloid leukemia, b) pts with leukocytosis, myelofibrosis and ring sideroblasts, c) pts with nuclear dysplasia (leukocyte chromatin clumping, isol7q syndrome), d) neutrophilic leukemia. (C) rare overlap cases between CML and CMML with bad prognosis. As evidence for MDS component in MDS-MPS it can be introduced: cases of MDS developing into MDS-MPS, presence of morphologic dysplasia and ring-sideroblasts, identical chromosomal aberrations as in MDS with the prevalence of complex rearrangement of karyotypes in group B and C, premature apoptosis in erythroid cells as in MDS, while the rest of bone-marrow cells demonstrate low apoptosis. Pathogenesis of these mixed syndromes will be commented. CONCLUSION: We present characteristic and classification of a relatively new and difficult diagnosis of MDS-MPS and bring the evidence for the MDS component in these syndromes.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Predictive Markers.