Published online Aug 6, 2013. doi: 10.5315/wjh.v2.i3.71
Revised: June 14, 2013
Accepted: June 18, 2013
Published online: August 6, 2013
Core tip: The integrated World Health Organization (WHO) and European Clinical, Molecular and Pathological classification of the myeloproliferative neoplasms include JAK2V617F mutated normocellular essential thrombocythemia (WHO-ET), prodromal polycythemia vera (PV), classical PV, and hypercellular ET due to megakaryocytic, granulocytic myeloproliferation. Evolution of prodromal PV into overt PV is common. JAK2/MPL wild hypercellular ET associated with prefibrotic primary megakaryocytic and granulocytic myeloproliferation is characterized by densely clustered immature dysmorphic megakaryocytes with bulky (bulbous) hyperchromatic nuclei, which are never seen in JAK2V617F mutated ET and PV, and also not in JAK2 wild type normocellular ET (WHO-ET) carrying the MPL515 mutation.