A 61-year-old woman was referred for the evaluation of shortness of breath, cough and tachycardia. She had a past history of stroke. Full blood count revealed a platelet count of 770 × 109/l. Echocardiography showed signs consistent with right ventricular overload. Computed tomography-pulmonary angiography demonstrated thromboembolic material in both pulmonary arteries (left, axial scan) and a large thrombus located in the descending aorta (right, sagittal reconstruction showing 68 × 11 mm thrombus). The patient was started on intravenous heparin. Reactive thrombocytosis was ruled out. Bone marrow biopsy showed increased numbers of enlarged, mature megakaryocytes and no significant abnormality of granulopoiesis or erythropoiesis, consistent with essential thrombocythaemia. The detection of a JAK2 V617F mutation confirmed the presence of a myeloproliferative neoplasm. Following the diagnosis of essential thrombocythaemia, the therapy was modified to dalteparin (15 000 u/day), hydroxycarbamide (1000 mg/day) and aspirin (75 mg/day).
Essential thrombocythaemia (ET) constitutes one of four classic myeloproliferative neoplasms. It is a prothrombotic condition, but very high platelet counts are associated primarily with haemorrhage. Survival is near-normal, but important morbidity and mortality derives from vascular complications, including arterial/venous thrombosis (the risk exceeds 20%), microvascular disturbances, and bleeding. Age ≥60 years and history of thrombosis are used to classify patients into low (0 risk factors) and high (≥1 risk factors) risk groups. Low-risk patients with extreme thrombocytosis (platelet count >1000 × 109/l) are considered separately because of the potential risk for bleeding. Treatment must be aimed at preventing thrombosis and bleeding. There is an expert consensus that low-risk patients should be managed with low-dose aspirin, whereas high-risk patients should receive cytoreductive therapy, with hydroxycarbamide being the drug of choice. Arterial/venous thrombosis should be managed accordingly to the appropriate guidelines.