Essential thrombocythemia and polycythemia vera

Background: Essential thrombocythemia (ET) and polycythemia vera (PV) belong to the group of myeloproliferative neoplasms (MPN). Due to improved molecular and pathological diagnostics, both diseases are increasingly diagnosed and even in younger patients nowadays. Prognosis is determined by arterial and venous thromboembolic complications and, in the late stage, by the occurrence of secondary myelofibrosis or acute myeloid leukemia.Aim: In addition to background information on the etiology and pathogenesis of both diseases, the current diagnosis according to the World Health Organization (WHO), clinical presentation, risk stratification, and therapy will be discussed.Materials and methods: This work is based on a selective literature search in the PubMed database on the topic of MPN, ET, and PV.Results and conclusion: In clinical practice, the differential diagnosis of thrombocytosis or polyglobulia is frequent and important. Today, ET or PV can be distinguished from secondary thrombocytosis or erythrocytosis on the basis of the WHO criteria. Here, the clinical as well as molecular diagnostics and bone marrow histology play a special role. If the rarer diagnosis of ET or PV is present, subsequent risk stratification is essential in order to identify patients who require cytoreductive therapy in addition to standard measures (acetylsalicylic acid, phlebotomy). Alongside the previously established drugs hydroxyurea and anagrelide, modern approaches with interferon alpha or the Janus kinase (JAK) inhibitor ruxolitinib are of particular importance.