Chronic Myeloprolipherative Neoplasms (MPNs) and Splanchnic Venous Thrombosis(SVT): Incidence and Risk Factors

Abstract 5057

There is evidence in literature of the clinical and pathogenetic role of JAK2 V617F mutation in MPN, while its contribute as an additional thrombotic risk factor in MPN patients is still under discussion. The jak2 mutation has been identified as occult marker in several patients with splanchnic venous thrombosis (SVT); morover, 45% of patients with Budd-Chiari syndrome (BCS) and 34% of patients with portal vein thrombosis (PVT) have associated MPN. On the other hand, the majority of BCS patients without MPN present additional congenital or acquired thrombosis risk factors.

The aim of the present study is to evaluate the incidence of SVT in MPN patients. We also evaluated the presence of other prothrombotic risk factors in MPN patients, in addition to the JAK-2 mutation.

Out of the 460 Ph1 negative MPN patients observed in our center from January 2000 to January 2010 and retrospectively evaluated, 9 patients (7 females and 2 males; 2%) presented SVT.

Six cases had Essential Thrombocythemia (ET), 2 Primary Myelofibrosis (PMF), and 1 Polycitemia Vera (PV). Five of the 6 cases with ET were females. Among the entire population of ET, SVT incidence was 3%. All the 9 patients diagnosed of SVT were JAK2 V617F positive and they were treated with antiaggregant and anticoagulation therapy; 6 received hydrossiurea.

Seven patients had SVT before MPN diagnosis, 2 of them had splenectomy at diagnosis for surgical decision. In these patients developing SVT before MPN diagnosis no other major thrombotic event occurred during follow-up. The remaining 2 MPNs patients presented asymptomatic SVT diagnosed by imaging techniques routinely performed during MPN follow up.

Interestingly, 75% of MPNs patients with SVT demonstrated at least one prothromobtic risk factor, such as factor V Leiden, Protein C deficiency, hyperhomocystinemia and 50% had 2 or more associated defects. MPNs patients without SVT (396) had a lower prevalence of prothrombotic risk factors and developed venous thrombosis in different anatomical sites: in these cases white blood cell count, platelets values and the presence of JAK2 V617F mutation correlate with the development of the thrombotic event.