Unusual venous thrombosis in a 35-year-old man

Abstract

A n otherwise healthy 35-year-old man presented to the emergency department with substantial pain in his upper abdomen that had lasted for several days and was radiating to his back. The patient had experienced a similar episode 4 months earlier that had not been investigated.On physical examination, the patient had hypertension (150/105 mm Hg), hepatosplenomegaly and pitting leg edema, with no signs of chronic liver disease. The results of laboratory investigations showed a hemoglobin level of 95 (normal 120-150) Duplex ultrasonography of the patient's abdomen showed an extensive, nearly occlusive thrombus in the infra-and intrahepatic inferior vena cava. The hepatic vein did not appear to be occluded, but the patchy appearance of the liver parenchyma and flow through a collateral vessel were consistent with obstruction of the hepatic outflow tract (Figure 1). Contrast-enhanced computer tomography (CT) and magnetic resonance imaging (MRI) of the abdomen and chest confirmed hepatomegaly (20 cm, with enlargement of the caudate lobe), splenomegaly (20 cm), thrombosis of the inferior vena cava extending to below the renal veins and mild ascites (Figure 2). We saw no congenital membranous web, anomaly or compression of the inferior vena cava. Results of echocardiography (including the proximal inferior vena cava) were normal, and endoscopy showed no varices.We started low-molecular-weight heparin therapy for thrombosis and ramipril for hypertension. The results of tests for heritable and acquired thrombophilia were negative. 1 However, a review of the pa tient's earlier primary care charts showed thrombocytosis (531-741 × 10 9 /L) on 5 routine blood tests over the previous 6 years. The patient's family history was noncontributory.The combination of thrombocytosis, which did not appear to be reactive or cytokine-driven (Box 1), 2 and substantial splenomegaly, despite only mild portal hypertension and thrombosis, suggested myeloproliferative neoplasm. On reviewing the smear of the patient's peripheral blood, we saw large abnormal platelets. Bone marrow aspiration and biopsy showed a hyperplastic marrow with megakaryocyte proliferation, atypia and clustering, increased eosinophils and increased reticulin fibres (grade 1/3). Genetic testing showed the presence of the JAK2 V617F mutation, with low (20%) JAK2 mutant allele burden; the results of testing for the BCR-ABL fusion gene were negative. We diagnosed essential thrombocythemia and started the patient on hydroxyurea (1000 mg/d) and warfarin. After 1 year of follow-up, the patient feels well and remains symptom-free. DiscussionThe patient's pain, edema, cholestatic liver enzymes, renovascular hypertension and proteinCases