Although it is well known that myeloproliferative neoplasms occur in younger patients, few large cohorts of such patients have been reported. Thus, our knowledge about circumstances of diagnosis, outcome and treatment is limited, especially for children and young adults. We therefore performed a systematic review of cases, published since 2005, concerning patients aged below 20 years at the time of diagnosis of essential thrombocythemia or polycythemia vera. We identified 396 cases of essential thrombocythemia and 75 of polycythemia vera. The median age at diagnosis was 9.3 and 12 years, respectively, and females constituted 57.6% and 45% of the groups, respectively. Half of the patients were asymptomatic at diagnosis. The proportion of so-called triple negativity was high: 57% in essential thrombocythemia and 73% in polycythemia vera. The incidence of thrombosis during the follow-up was 9.3% in patients with polycythemia vera and less, 3.8%, in those with essential thrombocythemia. Venous events were predominant (84.2%), with hemorrhagic episodes being rarer (<5%). The risk of evolution also seemed low (2% to myelofibrosis and no reports of acute leukemia), but the median follow-up was only 50 months. Survival curves were not available. Half of the patients received an antithrombotic drug and 40.5% received a cytoreductive drug. All data should be analyzed with care because of the proportion of missing data (10.7% to 74.7%). This review highlights interesting points concerning this population of young patients with myeloproliferative neoplasms, including that such patients were identified as negative for all common driver mutations, but also shows the need for larger contemporary cohorts with longer follow-up to assess the true prognosis of these patients.

• MeSH
• Asymptomatic Diseases MeSH
• Early Diagnosis MeSH
• Cytotoxins therapeutic use   MeSH
• Child MeSH
• Thrombocythemia, Essential diagnosis   drug therapy   genetics   pathology   MeSH
• Gene Expression MeSH
• Fibrinolytic Agents therapeutic use   MeSH
• Janus Kinase 1 genetics   MeSH
• Janus Kinase 2 genetics   MeSH
• Hemorrhage diagnosis   drug therapy   genetics   pathology   MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Mutation MeSH
• Polycythemia Vera diagnosis   drug therapy   genetics   pathology   MeSH
• Prognosis MeSH
• Splenomegaly diagnosis   drug therapy   genetics   pathology   MeSH
• Thrombosis diagnosis   drug therapy   genetics   pathology   MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Publication type
• Journal Article MeSH
• Systematic Review MeSH
• Names of Substances
• Cytotoxins MeSH
• Fibrinolytic Agents MeSH
• JAK1 protein, human MeSH Browser
• JAK2 protein, human MeSH Browser
• Janus Kinase 1 MeSH
• Janus Kinase 2 MeSH