Guideline on myeloproliferative neoplasms: Associacão Brasileira de Hematologia, Hemoterapia e Terapia Cellular

Myeloproliferative neoplasms (MPNs) constitute a group of hematologic clonal diseases that affect one or more myeloid lineages with an abnormal and abundant proliferation.16, 17 The World Health Organization (WHO) currently groups the MPNs into seven categories: Chronic myeloid leukemia (CML), chronic neutrophilic leukemia (CNL), polycythemia vera (PV), essential thrombocythemia (ET) primary myelofibrosis (PMF), chronic eosinophilic leukemia not otherwise specified (NOS) and, unclassifiable chronic myeloproliferative neoplasm (MPN-U). Mastocytosis is no longer included in that group.16 BCR-ABL1 fusion gene causes CML, identified by the translocation (9; 22) known as the Philadelphia chromosome (Ph), subject of prior guideline. Among the so-called Ph-negative MPNs, the most common ones include PV, ET, and PMF, herein the subject of this publication. PV, ET, and PMF share an anomaly in the JAK-STAT pathway, usually caused by genetic mutations on Janus kinase 2-JAK2 V617F, thrombopoietin receptor gene-myeloproliferative leukemia-MPL or calreticulin gene-CALR, which are mutually exclusive, and necessarily BCR-ABL negative (Table 1). PV, ET, and PMF share an anomaly in the JAK-STAT pathway, usually caused by mutations of the Janus kinase 2-JAK2 V617F genes, thrombopoietin receptor gene-myeloproliferative leukemia-MPL or calreticulin gene-CALR, that are mutually exclusive, and necessarily are BCR-ABL1 negative (Table 1). PV, ET, and PMF may arise alongside other mutations, as well as some cytogenetic abnormalities.16, 17 Despite the significant advances over recent years toward the characterization of genetic alterations, bone marrow morphological evaluation remains an important diagnosis tool.17 JAK2, MPL, and CALR mutations are not unique to these three conditions and may be present in other myeloid neoplasms, or even absent in some cases of PMF and ET.16 Table 1 Diagnostic criteria PV, ET, prefibrotic PMF and overt fibrotic PMF16(D).