Somatic mutations associated with chronic myelomonocytic leukemia and atypical chronic myeloid leukemia

| 1634 | haematologica | 2009; 94(12) The World Health Organization (WHO) classification of tumors of hematopoietic and lymphoid tissues includes within myeloid neoplasms the category “Myelodysplastic/myeloproliferative neoplasms”. According to Vardiman et al., these are “clonal myeloid neoplasms that at the time of initial presentation have some clinical, laboratory or morphologic findings that support a diagnosis of myelodysplastic syndrome (MDS), and other findings more consistent with myeloproliferative neoplasm (MPN)”. These disorders comprise chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia (aCML, BCR-ABL1 negative), juvenile myelomonocytic leukemia (JMML), and myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN, U). The best characterized of these unclassifiable conditions is the provisional entity defined as refractory anemia with ringed sideroblasts (RARS) associated with marked thrombocytosis (RARS-T). The diagnostic criteria for the myelodysplastic/myeloproliferative neoplasms are summarized in Table 1, while representative peripheral blood and bone marrow smears are reported in Figures 1, 2 and 3. As recently underlined, these conditions can only be categorized by a careful multiparametric approach, which includes bone marrow and peripheral blood morphology and other laboratory and clinical findings. In the last few years, however, our understanding of the molecular pathogenesis of myelodysplastic/myeloproliferative neoplasms has improved considerably. Here we will concisely analyze these advances and how they may impact our approach to these conditions in the near future.