The myelodysplastic/myeloproliferative neoplasms: myeloproliferative diseases with dysplastic features.

The 2001 World Health Organization (WHO)-sponsored classification of hematopoietic tumors has, for the first time, clearly defined a group of rare myeloid neoplasms termed myelodysplastic/myeloproliferative diseases (MDS/MPDs). This group includes three main entities, chronic myelomonocytic leukemia, atypical chronic myeloid leukemia and juvenile myelomonocytic leukemia, and also several less well defined, 'unclassifiable' disorders with MDS/MPN-like features. In the upcoming fourth edition of the WHO fascicle, due out later this year, the term 'MPD' is replaced by 'myeloproliferative neoplasm (MPN)'. Accordingly, the term MDS/MPD is being replaced by 'MDS/MPN' that will be used in this review. Although much progress has been made in understanding the molecular pathogenesis of myeloid neoplasms, most of the diseases included in the group of MDS/MPN still remain 'clinicopathologically assigned'. In other words, they can only be accurately categorized by a careful multiparametric approach that is based on the integration of bone marrow and peripheral blood morphology with other laboratory and clinical findings. The current 'spotlight' review provides practical guidelines, which should allow for a reproducible classification of these uncommon neoplasms when encountered in clinical practice.