Portal vein thrombosis secondary to occult polycythemia vera

Portal vein thrombosis (PVT) is an uncommon finding in patients without cirrhosis. The underlying x\aetiology is challenging and the condition has a wide differential diagnosis. We present a case of PVT in an anaemic patient with chronic iron and folic acid deficiency masking underlying polycythemia vera (PV). Only a careful review of the patient’s clinical history allowed the identification of a short period of laboratory erythrocytosis, 6 months before the clinical onset of PVT, while the patient was on iron and folic acid supplementation. The finding raised clinical suspicion of PV previously masked by iron deficiency anaemia. Subsequent investigation confirmed the presence of the JAK2 V617F mutation and, ultimately, showed that the patient met all diagnostic criteria for PV. Myeloproliferative disorders (MPD) are associated with systemic prothrombotic states. PV is distinguished clinically from other MPD by the presence of increased red blood cell mass. Moreover, patients with abnormal haematocrit values in the pre-JAK2 V617F era may have had occult or latent PV. Diagnosis confirmation requires a combination of major and minor criteria to capture occasional cases of occult PV. This case emphasizes the importance of always considering MPD in the aetiological investigation of PVT, even in patients who apparently do not fulfil the diagnostic criteria.