The study is observational, longitudinal, retrospective and prospective, on patients with PV. Patients with PV diagnosed from 2000 to 2023 according to WHO2017 criteria will be considered. The main purpose of the study is to determine the impact of clinical and laboratory characteristics of Polycythemia Vera on patients' prognosis, understood as long-term survival

The structured collection of data necessary for the evaluation of the objectives will take place through the creation of a specific electronic archive with an expected duration of 7 years, possibly extendable. The electronic archive may be used to review case histories and to obtain or confirm new scientific evidence on Polycythemia Vera. Patients will be followed and treated within the care pathway provided by normal clinical practice.

The following elements will be considered in each patient: age, recent and remote pathological history, characteristics of PV onset, histological, cytogenetic and molecular investigations of diagnostic definition, medical therapies performed, type of response to the therapies performed, complications of these therapies and pathology. All useful data will be collected exclusively through consultation of outpatient medical records.

The planned enrollment period is 60 months (January 2019-December 2023). The observation period of enrolled patients is at least 2 years.

Inclusion Criteria:

• Patients diagnosed with PV according to WHO 2017 criteria,
• Obtaining informed consent for data collection and processing

Exclusion Criteria:

• None

The incidence of PV is approximately 11 x 1,000,000 patient-years. For the purpose of the registry, clinical/laboratory data collection will be expanded to 22 Hematology Centers experienced in the study of chronic myeloproliferative neoplasms. Overall, about 150 new diagnoses per year are expected from all Centers. Considering that about 20 percent of patients will not be able to be included for various reasons (lack of diagnosis according to WHO2017 criteria, patient's failure to refer to Hematology Centers, refusal to participate in the study), the registry is expected to include clinical data from about 2000 cases diagnosed from 2000 to the year 2023.