Portal or hepatic vein thrombosis as the first presentation of a myeloproliferative disorder in patients with normal peripheral blood counts

Myeloproliferative disorders (MPD) are associated with an increased risk of thrombotic complications. We describe three patients with portal or hepatic vein thrombosis and normal peripheral blood counts who had MPD on bone marrow morphology and growth factor-independent megakaryocyte or erythroid colony growth in vitro. The peripheral blood counts have become abnormal subsequently in two patients. Patients presenting with unexplained portal or hepatic vein thrombosis should be investigated systematically for the presence of a MPD, which may not be apparent using conventional diagnostic criteria.