Polycythemia vera in children: a literature review

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) are clonal myeloid diseases characterized by hyperproduction of differentiated hematopoietic cells. Polycythemia vera (PV) belongs to the group of MPNs and is associated with a high risk of thrombosis, hemorrhagic complications and phenotypic transformation of the disease into myelofibrosis or acute myeloid leukemia. PV is extremely rare among children, first of all, when diagnosing the disease, it is necessary to exclude the secondary cause of erythrocytosis. The incidence of PV is 0.18 per 100,000 people-years the child population. Only half of pediatric patients with PV have symptoms associated with polycythemia. In most children, PV is diagnosed accidentally when an increase in hemoglobin concentration or hematocrit is noted in the full blood count. The mutation JAK2 gene is included in the diagnostic criteria of PV, but its prevalence among children is significantly lower than among adults. In adult patients with PV, the tactics of therapy were determined depending on the risk of complications of the disease: age over 60 years, a history of thrombotic complications. Children rarely have a history of thrombotic events and therefore belong to the low-risk group. Risk factors related to the prognosis and complications of the disease have not been identified for them, data on the results of сytoreductive therapy are also limited, a general algorithm for the treatment of PV in the pediatric population has not been developed, mainly the experience of therapy is extrapolated from adult clinical treatment protocols.