[Portal vein thrombosis as the main symptom of unclassified JAK2-positive myeloproliferative neoplasm--case report].

We report a case of a patient with a diagnosis of myeloproliferative neoplasm, unclassifiable, manifested only portal vein thrombosis and followed by cirrhosis of the liver. 37-year-old patient, previously healthy, without congenital thrombophilia, without prior thrombosis, with normal peripheral blood morphology were signs of extensive portal vein system, with massive collateral circulation. Patient did not meet the criteria for diagnosis of any of the classic myeloproliferative neoplasms. Bone marrow examination revealed hyperplasia and presence of single polymorphic megakaryocytes. Positive JAK2V617F mutation status was typical for myeloproliferative neoplasm. Therefore, that the portal system thrombosis is, sometimes accompanying symptom of other myeloproliferative neoplasm, caused by mutations, including polycythemia vera, essential thrombocythaemia and primary myelofibrisis, one can assume that between this mutation and observed in this patient thrombosis is relationship, despite the absence of changes in peripheral blood. This may suggest that we are dealing with myeloproliferative neoplasm, in which platelets are indeed produced in normal numbers, but they are functionally activated, causing disturbances apparently unusual for cancer. This requires confirmation in further studies.