Myelodysplastic and myeloproliferative type of chronic myelomonocytic leukemia--distinct subgroups or two stages of the same disease?

Abstract

Several authors have tried to solve the problems in the classification of CMML. A fully suitable classification does not exist. The goal of our study was to determine common and different signs of MD and MP type of CMML and to observe frequency of shifts from MD to MP-CMML. Sixty nine CMML patients were divided according to FAB proposal into two groups: 31 patients into the MD group (WBC < or = 13 x 10(9)/l) and 38 patients into the MP group (WBC < or = 13 x 10(9)/l). Presenting features and the course of the disease in both groups were evaluated. The median age of patients was not different in both groups (71.5 and 74 years, respectively), male/female ratio was 1.1 and 2.4, respectively. The median follow-up time was 15.5 months (1-58.8) in MP group and 24 months (2-118) in MD group. In MP group splenomegaly, hepatomegaly, lymphadenopathy, abnormal karyotype and skin involvement were found more often than in MD group. Median LDH value was higher in MP group. Probability of survival was higher in the MD group than in MP group (median 30 and 11 months, respectively). Leukaemia transformation frequency was similar in both groups. In 12 out of 24 (50%) MD group patients WBC increased during the course of the disease over 13 x 10(9)/l. Oscillation of WBC values below and over 13 x 10(9)/l was observed in three patients. During the follow-up time number of patients with splenomegaly and/or immature granulocytes in the PB increased. After inclusion of 12 patients who shifted from MD to MP group a new CMML group resulted characterised by longer median survival (17 months) due to a higher number of patients in an earlier stage of the disease. Failure of evolution of myeloproliferative signs and lower frequency of AL in the remaining group might be explained by an early stage of CMML, untimely deaths due to unrelated causes and/or by patients suffering of RA with monocytosis rather than of CMML. In summary, our data suggest, that evolution from MD-CMML to MP-CMML is a frequent event and that MD-CMML could be the early stage of CMML in most of cases. The WBC at diagnosis as the single criterion for subclassification of CMML does not seem to be fully justified. We propose that CMML should not be divided in MD and MP types and that monitoring of patients and search for other signs of myeloproliferation such as PB immature granulocytes, splenomegaly, lymphadenopathy, skin involvement, pleural or peritoneal effusions, spontaneous growth of CFU-GM in vitro should be taken in consideration for a better classification of CMML, which would have an impact on the therapeutic approach.