title: A lower intensity of treatment may underlie the increased risk of thrombosis in young patients with masked polycythaemia vera.
abstract: In patients who do not meet the World Health Organization (WHO) criteria for overt polycythaemia vera (PV), a diagnosis of masked PV (mPV) can be determined. A fraction of mPV patients may display thrombocytosis, thus mimicking essential thrombocythaemia (ET). No previous studies have examined clinical outcomes of mPV among young JAK2-mutated patients. We analysed a retrospective cohort of 538 JAK2-mutated patients younger than 40 years, after a re-assessment of the diagnosis according to the haemoglobin threshold for mPV. In this cohort of patients, 97 (18%) met the WHO criteria for PV, 66 patients (12%) were classified as mPV and 375 (70%) as JAK2-mutated ET. Surprisingly, a significant difference in the incidence of thrombosis was found when comparing mPV versus overt PV patients (P = 0·04). In multivariate analysis, the only factor accounting for the difference in the risk of thrombosis was the less frequent use of phlebotomies and cytoreduction in mPV patients compared to those with overt PV. Thus, we emphasize the need for the identification of mPV in young JAK2-mutated patients in order to optimize their treatments.
authors.affiliation: Haematology and Bone Marrow Transplant Unit, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Lussana
authors.forename: Alessandra
authors.initials: A
authors.lastname: Carobbio
authors.forename: Maria L
authors.initials: ML
authors.lastname: Randi
authors.forename: Chiara
authors.initials: C
authors.lastname: Elena
authors.forename: Elisa
authors.initials: E
authors.lastname: Rumi
authors.forename: Guido
authors.initials: G
authors.lastname: Finazzi
authors.forename: Irene
authors.initials: I
authors.lastname: Bertozzi
authors.forename: Lisa
authors.initials: L
authors.lastname: Pieri
authors.forename: Marco
authors.initials: M
authors.lastname: Ruggeri
authors.forename: Francesca
authors.initials: F
authors.lastname: Palandri
authors.forename: Nicola
authors.initials: N
authors.lastname: Polverelli
authors.forename: Elena
authors.initials: E
authors.lastname: Elli
authors.forename: Alessia
authors.initials: A
authors.lastname: Tieghi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Iurlo
authors.forename: Marco
authors.initials: M
authors.lastname: Ruella
authors.forename: Mario
authors.initials: M
authors.lastname: Cazzola
authors.forename: Alessandro
authors.initials: A
authors.lastname: Rambaldi
authors.forename: Alessandro M
authors.initials: AM
authors.lastname: Vannucchi
authors.forename: Tiziano
authors.initials: T
authors.lastname: Barbui
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006454:Hemoglobins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics / Q000378:metabolism; D008297:Male; D009154:Mutation; D011087:Polycythemia Vera / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000628:therapy; D012307:Risk Factors; D013927:Thrombosis / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000235:genetics
chemical_list: D006454:Hemoglobins; C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: JAK2 mutation; essential thrombocythaemia; masked polycythaemia; polycythaemia vera; thrombosis