Tumours of haematopoietic and lymphoid tissues
Polycythaemia vera (PV) is a chronic myeloproliferative neoplasm (MPN) characterized by increased red blood cell production independent of the mechanisms that normally regulate erythropoiesis. Virtually all patients carry the somatic gain-of-function mutation of the Janus 2 kinase gene, JAK2 V617F or another functionally similar JAK2 mutation that results in proliferation not only of the erythroid lineage but of the granulocytes and megakaryocytes as well, i.e. “panmyelosis”. Three phases of PV may be recognized:
1. A prodromal, pre-polycythaemic phase characterized by borderline to only mild erythrocytosis;
2. An overt polycythaemic phase, associated with a significantly increased red cell mass; and
3. A “spent” or post-polycythaemic myelofibrosis phase (post-PV MF) in which cytopenias, including anaemia, are associated with ineffective haematopoiesis, bone marrow (BM) fibrosis, extramedullary haematopoiesis (EMH), and hypersplenism.
The natural progression of PV also includes a low incidence of evolution to a myelodysplastic/pre-leukaemic phase and/or to acute leukaemia (AML). All causes of secondary erythrocytosis, inheritable polycythaemia and other MPN must be excluded. The diagnosis requires integration of clinical, laboratory and BM histological features
Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J, Vardiman JW (Eds.)
as outlined in Table 2.02.
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues
International Agency for Research on Cancer: Lyon 2008
> Related Topics
Introduction: Myeloid Neoplasms
|Schematic representation of the evolution of the disease process in polycythaemia vera.|