Classic Essential Thrombocythemia Presenting with Pulmonary Artery Thromboembolism

Abstract

Background: Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by abnormal proliferation of megakaryocytes in the bone marrow, resulting in persistent thrombocytosis in the peripheral blood and clinical manifestations including thrombotic and hemorrhagic complications. Approximately 90% of patients with ET harbor driver mutations in JAK2, CALR, or MPL, with JAK2V617F being the most frequently detected mutation.The JAK2V617F mutation induces constitutive activation of the JAK–STAT signaling pathway, leading to abnormal megakaryocytic proliferation and increased platelet production. Consequently, patients are predisposed to thrombotic complications; however, qualitative platelet dysfunction may also contribute to an increased risk of bleeding. Among large-vessel thrombotic complications, venous thromboembolism is relatively common, whereas pulmonary artery thromboembolism is an uncommon complication. Moreover, thrombotic risk is generally lower in patients with JAK2-negative ET. Case presentation: In this report, we present a rare case of essential thrombocythemia presenting with respiratory failure secondary to pulmonary artery thromboembolism. Conclusion: This case demonstrates that essential thrombocythemia may initially manifest with life-threatening thrombotic complications, including pulmonary thromboembolism, even in the absence of the JAK2 V617F mutation. Accordingly, unexplained thrombocytosis warrants evaluation for an underlying myeloproliferative neoplasm, while early assessment of thrombotic risk is essential for guiding appropriate clinical management and reducing the risk of adverse outcomes.