The World Health Organization (WHO) classification of myeloproliferative neoplasms (MPN) [1,2] was revised in 2008 and defines the diagnosis of Essential Thrombocythemia (ET) according to the following algorithm:
A patient must meet 4 major criteria:
Major Criteria :
- Platelet Count ≥ 450 x 109 / l
- Both of the following:
- Megakaryocyte proliferation with large and mature morphology
- No or little granulocyte or erythroid proliferation
- Not meeting WHO criteria for CML, PV, PMF, MDS or other myeloid neoplasm.
- One of the following:
- Demonstration of the JAK2 V617F mutation
- Demonstration of a other clonal marker
- No evidence of reactive thrombocytosis
- Swerdlow S, Campo E, Harris N. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. IRAC Press. 2008:Lyon, France
- Tefferi A, Thiele J, Vardiman JW. The 2008 World Health Organization classification system for myeloproliferative neoplasms: order out of chaos. Cancer. 2009;115(17):3842-3847.
- Visit also the FIM (French Intergroup MPD) website.