Polycythemia Vera

Polycythemia Vera is one of the myeloproliferative neoplasms, a group of blood cancers in which bone marrow cells multiply uncontrollably. In PV, the overproduction of red blood cells increases blood volume and viscosity (thickness), which impairs blood flow and oxygen delivery despite elevated hemoglobin levels. The high blood viscosity also increases risk of blood clots (thrombosis) and bleeding complications. About 95% of PV patients carry the JAK2 V617F mutation, with most remaining cases having mutations in CALR or MPL genes. These mutations cause uncontrolled cell growth independent of normal growth signal regulation. Patients often present with constitutional symptoms including fatigue, headaches, and visual disturbances. The pathognomonic symptom of aquagenic pruritus (itching triggered by water contact) occurs in about half of patients. Splenomegaly (enlarged spleen) occurs in 75% of patients. Long-term complications include risk of thrombotic events (stroke, heart attack, deep vein thrombosis) and potential transformation to myelofibrosis or acute leukemia.