Background: Patients with Myeloproliferative Neoplasms–(MPN) have a high risk of thrombotic complications. Portal vein thrombosis is a severe complication, which in many cases, appears at the onset of the disease; the risk factors are related to the presence of qualitatively altered thrombocytes and leucocytes, leading to their activation and appearance of leukocytes–platelet–aggregates; anomalies of portal vein endothelial cells are also implicated. The presence of JAK2V617F mutation increases the risk for splahnic thrombosis.

Methods and results: We present three patients with portal vein thrombosis and Budd Chiari syndrome, who were further diagnosed with MPN–the thrombosis was the onset event of the disease

Conclusion: Patients were diagnosed with thrombosis of the portal vein before being diagnosed with MPN. Splenectomy was not associated with risk of thrombosis for the two cases in which it was performed; for one case, splenectomy was a therapeutic method to resolve portal hypertension. All patients had homozygous JAK2 mutation, which is associated in recent studies with increased risk of portal, mesenteric thrombosis. The high number of platelet was difficult to control for all patients. Bone marrow biopsy and determination of JAK status are valuable investigations for patients who have splenoportal thrombosis, with no apparent identifiable cause.