Clinical Features of Idiopathic Erythrocytosis Compared to Polycythemia Vera JAK-2 V617F Positive and Negative Patients

Abstract 5172 The introduction of JAK-2 V617F mutation in the diagnostic process of patients with erythrocytosis has led to a better definition of Polycythemia Vera (PV) patients, who had the mutation in > 90% of cases: however, in the real-life many patients with otherwise unexplained Hb and Ht elevation and lack of JAK-2 V617F mutation are located in the gray zone of the so-called Idiopathic Erythrocytosis (IE). In order to highlight clinical features of patients with IE, we revised 247 patients with primary erythrocytosis (i.e. excluding cases with respiratory and/or severe cardiovascular diseases) diagnosed in 2 Hematological Institutions in Rome from 6/1985 to 12/2010 with a evaluable JAK-2 mutational status at diagnosis or during the follow-up. Were considered as “PV JAK-2 positive” all patients with presence of mutation V617F at diagnosis or during follow-up. Among the patients who resulted JAK-2 V617F negative, were considered as “PV JAK-2 negative” all patients classifiable as PV according to PVSG criteria (if diagnosed before 1/2002) or WHO 2002 criteria (if diagnosed after 1/2002): the remaining patients were classified as “IE”. With these criteria, 181 patients (73.2%) were PV JAK-2 positive, 26 (10.5%) PV JAK-2 negative and 40 (16.3%) IE: the main clinical features of these 3 groups at diagnosis and during the course of disease are summarized in the table. Comparing the 3 groups for the above features, there was a very significative (p Disclosures: No relevant conflicts of interest to declare.