MPL-Positive Essential Thrombocytosis Presenting as Budd-Chiari Syndrome in a Middle-Aged Woman with an Initially Normal Platelet Count

Budd-Chiari syndrome (BCS) results from an occlusion of the hepatic venous flow which in turn leads to portal hypertension causing ascites and other signs of liver dysfunction. Here, we present the case of a 43-year-old woman with recurrent ascites who was found to have BCS secondary to an inferior vena cava thrombosis extending into the hepatic veins. Although she had a normal platelet count on admission, additional laboratory investigations revealed an MPL mutation. She was discharged on anticoagulation with apixaban and later found to have thrombocytosis on repeat blood work, confirming the diagnosis of essential thrombocytosis, following which she was started on myelosuppressive therapy with hydroxyurea. LEARNING POINTS: Complete work-up to evaluate for myeloproliferative disorders should be done for patients with unexplained thrombocytosis as they are at high risk of thrombotic complications. Ninety percent of patients with essential thrombocytosis have either JAK2, calreticulin or MPL mutation. Patients with essential thrombocytosis who have a thrombotic episode normally require lifelong anticoagulation.