Myeloproliferative Neoplasms
Summary of Key Points
Differential Diagnosis
• All three classic BCR-ABL1− MPNs may be considered as diagnoses of exclusion, because a specific diagnostic marker is currently lacking.
• The presence of a JAK2 mutation distinguishes PV from all other causes of polycythemia, and ET and PMF from reactive thrombocytosis or myelofibrosis, respectively.
Diagnostic Evaluation
• Evaluation of suspected PV should start with peripheral blood screening for JAK2V617F and serum erythropoietin (Epo) measurement.
• More than 90% of PV patients are expected to display the JAK2 mutation, whereas a low serum Epo level should capture most of the JAK2V617F− cases, which might display other JAK2 mutations such as an exon 12 mutation.
• Bone marrow examination remains essential in the diagnosis of ET and PMF.
Risk Stratification
• Both PV and ET display a near-normal life expectancy in the first decade of the disease. The major problem during this period is thrombosis that may occur in as many as 30% of the patients.
• A history of thrombosis or age older than 60 years is associated with a high-risk of thrombosis.
• Platelet count by itself has not been significantly associated with thrombosis in either PV or ET.
• The presence of advanced age, anemia, red cell transfusion-dependency, thrombocytopenia, leukocytosis, severe constitutional symptoms, circulating blasts or unfavorable karyotype are all adverse risk factors in PMF.
