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- Susan S Graham, MS, MT (ASCP)SHCM⇑
- Address for Correspondence: Susan S Graham, MS, MT (ASCP)SHCM, Dept. of Clinical Laboratory Science, Assistant Dean, College of Health Professions, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210, 315-464-5334, grahams{at}upstate.edu
Identify the mutations associated with essential thrombocythemia (ET).
Describe the clinical presentation of patients with essential thrombocythemia.
Recall the 2008 WHO criteria for diagnosis of essential thrombocythemia.
Differentiate essential thrombocythemia from other myeloproliferative neoplasms and reactive thrombocytosis.
Discuss the expected clinical course of patients with essential thrombocythemia.
Extract
INTRODUCTION Essential thrombocythemia (ET) is a clonal stem cell disorder characterized by sustained thrombocytosis > 450 x 109/L in the peripheral blood, increased numbers of large, mature megakaryocytes in the bone marrow, and clinically by episodes of thrombosis or hemorrhage.1 Initially described in 1934, ET was recognized as a primary thrombocythemia and ultimately grouped with other myeloproliferative neoplasms with pancellular hyperproliferation of bone marrow elements, increased cellular presence in the peripheral blood, and organomegaly.2
The discovery of the Philadelphia chromosome and its subsequent association with the BCR/ABL1 mutation led the way to the grouping of ET with the other BCR/ABL-negative myeloproliferative neoplasms, polycythemia vera (PV) and primary myelofibrosis (PMF). It was later found that these disorders shared the Janus kinase 2 (JAK2 V617F) mutation. This mutation was found in 90% of patients with PV, and 50% of patients with either ET or PMF.3
This article explores the pathology and laboratory presentation of ET along with the diagnosis and clinical course of the disease.
Pathology The etiology of ET is unknown. Studies suggest that the JAK2 V617F mutation is associated with cytokine-independent proliferation of cytokine-dependent cell lines.4 While this would be consistent with the hyperproliferation of the megakaryocytic cell line, it does not entirely explain the abnormality, given that approximately half of the patients with ET are JAK2 V617F negative. JAK2 V617F activates a tyrosine kinase of the erythropoietin and thrombopoietin receptors that transform hematopoietic precursors. Mutations in MPL and TET2 oncogenes have also been identified in some patients with ET…
Identify the mutations associated with essential thrombocythemia (ET).
Describe the clinical presentation of patients with essential thrombocythemia.
Recall the 2008 WHO criteria for diagnosis of essential thrombocythemia.
Differentiate essential thrombocythemia from other myeloproliferative neoplasms and reactive thrombocytosis.
Discuss the expected clinical course of patients with essential thrombocythemia.
- © Copyright 2011 American Society for Clinical Laboratory Science Inc. All rights reserved.
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