The revised World Health Organization diagnostic criteria for polycythemia vera, essential thrombocytosis, and primary myelofibrosis: an alternative proposal

Prodromal myeloproliferative neoplasms: The 2008 WHO classification

“…Contrasting a number of previous [5][6][7] and recently published classification systems [8,9], the rationale was the generation of an useful interface between all these different parameters that are not only aimed to increase diagnostic sensitivity and specificity, but also provides easily applicable algorithms for routine clinical practice [2,3,10]. In this regard, diagnostic criteria for the classical Philadelphia chromosome-negative (Ph 12 ) MPN as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), have been substantially changed by inclusion of the JAK2V617F mutation status and similar activating mutations [3,4].…”

“…Unfortunately, the PVSG [5,7,21] and other classification systems [8,9] do not regard BM morphology as one of the yardsticks for diagnosis. Although, in a recently published classification, the diagnostic platelet level was reduced to a persistent thrombocytosis greater than 400 3 10 9 /l, ET is still considered as the only MPN without specific phenotype [9].…”

“…Unfortunately, the PVSG [5,7,21] and other classification systems [8,9] do not regard BM morphology as one of the yardsticks for diagnosis. Although, in a recently published classification, the diagnostic platelet level was reduced to a persistent thrombocytosis greater than 400 3 10 9 /l, ET is still considered as the only MPN without specific phenotype [9]. Because an isolated thrombocytosis can be found in initial manifestations of PV and PMF, it was argued that ET is a diagnosis of exclusion and should not be strictly regarded as a single disease entity [8,9].…”

“…Particularly, to underscore the fact that overt myelofibrosis is not a necessary diagnostic feature of this MPN category, the term PMF was recommended to the WHO by the International Working Group on Myelofibrosis [117]. In this context, the crucial and often disregarded differentiation from terminal stage PV and ET presenting with findings of MMM/AMM [8,9,21,115] was also taken into account [118].…”

A retrospective study on 226 polycythemia vera patients: impact of median hematocrit value on clinical outcomes and survival improvement with anti-thrombotic prophylaxis and non-alkylating drugs

“…Recently, the World Health Organization (WHO) proposed new criteria, in consideration of the discovery of JAK2 mutation role in PV [19,20]. However, before the discovery of JAK2 mutations [21][22][23][24][25], differential diagnosis between PV and secondary erythrocytosis was not always immediate and it is unclear how previous WHO diagnostic recommendations have been actually followed in general practice, outside of clinical trials.…”