SPOTLIGHT REVIEW Classification and diagnosis of myeloproliferative neoplasms: The 2008 World Health Organization criteria and point-of-care diagnostic algorithms

The 2001 World Health Organization (WHO) treatise on the classification of hematopoietic tumors lists chronic myelopro-liferative diseases (CMPDs) as a subdivision of myeloid neoplasms that includes the four classic myeloproliferative disorders (MPDs)Fchronic myelogenous leukemia, polycythe-mia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF)Fas well as chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia/hypereosinophilic syn-drome (CEL/HES) and ‘CMPD, unclassifiable’. In the upcoming 4th edition of the WHO document, due out in 2008, the term ‘CMPDs ’ is replaced by ‘myeloproliferative neoplasms (MPNs)’, and the MPN category now includes mast cell disease (MCD), in addition to the other subcategories mentioned above. At the same time, however, myeloid neoplasms with molecularly characterized clonal eosinophilia, previously classified under CEL/HES, are now removed from the MPN section and assem-bled into a new category of their own. The WHO diagnostic criteria for both the classic BCR–ABL-negative MPDs (that is PV, ET and PMF) and CEL/HES have also been revised, in the 2008 edition, by incorporating new information on their molecular pathogenesis. The current review highlights these changes and also provides diagnostic algorithms that are tailored to routine clinical practice