The peripheral blood smear often demonstrates normochromic, normocytic red blood cells (may be hypochromic and microcytic if iron deficiency is also present), thrombocytosis, and leukocytosis.
The bone marrow may show hypercellularity, megakaryocytic proliferation, fibrosis, and the absence of stainable iron. If the marrow shows fibrosis, the spleen will enlarge due to extramedullary hematopoiesis. More than 95% of cases of PV have a JAK2 mutation (which can be detected on peripheral blood or bone marrow).
PV is a chronic condition with many phases. When the disease is more progressed, there is possibility of increased fibrosis or that it may transform into acute leukemia.
D45 – Polycythemia vera
128841001 – Polycythemia vera
Differential Diagnosis & Pitfalls
- Secondary polycythemia can occur in a variety of settings: living at high altitude, cardiac or pulmonary disease causing low oxygenation ( [COPD], , etc), erythropoietin-secreting tumors, drugs, and reduced plasma volume, among others. Erythropoietin levels are very helpful in distinguishing primary and secondary polycythemia. Secondary polycythemia is more prevalent than PV.
- Erythropoietin receptor mutations
- Splenomegaly can occur with other hematologic disorders including leukemia and other myeloproliferative neoplasms, as well as nonmalignant causes (autoimmune or infection).