This is a 3-year multi-centre prospective in vitro study. 120 patients with MPN (ET (n=45), PV (n=45), and MF (n=30)) will be enrolled for a period of 22 months. Follow-up: 12 months. Patients (ET=Group A; PV=Group B; MF=Group C) will be enrolled at the Complex Operative Unit of Haematology-IRCCS Azienda Ospedaliero-Universitaria di Bologna and at the Haematology Centres of Reggio Emilia, Brescia, Meldola, and Ravenna. Peripheral blood samples from patients with ET, PV, and MF (Group A-C; 40 ml) and/or bone marrow samples from patients with ET and PV (Group A, B; 5 ml) will be collected at diagnosis as part of normal clinical practice. The samples will be analysed at the Complex Operative Unit of Haematology-IRCCS Azienda Ospedaliero-Universitaria di Bologna in collaboration with the Istituto Romagnolo per lo Studio dei Tumori 'Dino Amadori' - IRST IRCCS (analysis of EV size and concentration) and with the University of Perugia (analysis of EV lipid cargo). The data analysis will be carried out in collaboration with the Department of Physics and Astronomy of the University of Bologna.