PV is caused by the overproduction of erythrocyte precursor clones in the bone marrow. PV may also exhibit increased proliferation of white cells and platelets, leading to pancytosis, although overproduction is most pronounced in the erythroid line. Theories regarding the cause of increased production of erythrocyte precursors include hypersensitivity to erythropoietin (EPO) or other growth factors, EPO-independent clonal growth of progenitor cells, and inhibition of apoptosis in progenitor cells. This condition occurs most commonly in individuals older than 60 and has an increased prevalence in men (2:1 vs. women).
The general patient symptoms mentioned previously for myeloproliferative disorders are common in PV patients along with some additional, more specific symptoms, including:
- Pruritis (intense itching after bathing or exposure to warm water)
- Purple spots or patches on the skin that may throb or cause pain
- Headache and problems with vision
- A feeling of pressure or fullness below the ribs on the left side
- Reddened face that looks like a blush or sunburn
