From the Guidelines
Polycythemia vera (PV) is a chronic myeloproliferative neoplasm characterized by excessive production of red blood cells, often accompanied by increased white blood cells and platelets, resulting from a JAK2 gene mutation in hematopoietic stem cells, leading to uncontrolled cell proliferation. The condition is typically diagnosed based on revised WHO criteria, including lower threshold values for hemoglobin and hematocrit, and bone marrow examination 1. Key characteristics of PV include:
- Excessive production of red blood cells, white blood cells, and platelets
- Presence of JAK2 gene mutation (typically JAK2 V617F) in hematopoietic stem cells
- Uncontrolled cell proliferation leading to increased risk of thrombosis, bleeding, and transformation to acute leukemia
- Risk stratification based on age, history of thrombosis, and other factors to guide management
Management of PV depends on risk stratification, with low-risk patients (age <60 years, no history of thrombosis) typically treated with low-dose aspirin (81-100 mg daily) and phlebotomy to maintain hematocrit below 45% 1. High-risk patients require cytoreductive therapy, with hydroxyurea as first-line treatment (starting at 500-1000 mg daily, adjusted based on blood counts) 1. Alternative options include interferon-alpha (particularly for younger patients or during pregnancy) or ruxolitinib for those intolerant or resistant to hydroxyurea 1. Regular monitoring of blood counts is essential, and patients should be evaluated for complications such as thrombosis, bleeding, progression to myelofibrosis, or transformation to acute leukemia. Supportive measures include managing pruritus (antihistamines, SSRI antidepressants), maintaining hydration, and avoiding activities that increase thrombotic risk. The disease is chronic and requires lifelong management, with treatment goals focused on preventing complications and improving quality of life.
From the Research
Characteristics of Polycythemia Vera (PV)
- PV is a chronic myeloproliferative neoplasm characterized by activating mutations in Janus kinase 2, erythrocytosis, and bone marrow hypercellularity 2
- It is associated with an increased red blood cell mass and increased risk of thrombosis 3
- Erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) is a required diagnostic criterion, although thrombocytosis (53%) and leukocytosis (49%) are common 3
- Patients may have pruritus (33%), erythromelalgia (5.3%), transient visual changes (14%), and splenomegaly (36%) with abdominal discomfort 3
- More than 95% of patients have a JAK2 gene variant, which helps distinguish PV from secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea 3
Clinical Features and Prognosis
- The dominant clinical characteristics include erythrocytosis (with or without leukocytosis/thrombocytosis), thrombotic events, and symptoms 4
- Increased risk of mortality is mainly caused by thrombotic events and progression to post-polycythemia vera myelofibrosis (PPV-MF) or secondary acute myeloid leukemia (sAML) 4
- The most important prognostic factors include age and a history of thrombotic events, although recent evidence has indicated that leukocytosis and additional cytogenetic aberrations may also be of significant prognostic value 4
- Median survival from diagnosis was 14.1 to 27.6 years in 7 cohorts (1545 individuals) 3
Diagnosis and Risk Stratification
- Bone marrow morphology remains the cornerstone of diagnosis 5
- The presence of JAK2 mutation is expected in PV while approximately 90% of patients with ET express mutually exclusive JAK2, CALR or MPL mutations (so called driver mutations) 5
- In PV, two risk categories are considered: high (age >60 years or thrombosis history present) and low (absence of both risk factors) 5