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Overview of Myeloproliferative Neoplasms

By

Jane Liesveld

, MD, James P. Wilmot Cancer Institute, University of Rochester Medical Center

Last full review/revision Jul 2022| Content last modified Sep 2022
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Myeloproliferative neoplasms are clonal proliferations of bone marrow stem cells, which can manifest as an increased number of platelets, red blood cells (RBCs), or white blood cells (WBCs), alone or in combination, in the circulation and sometimes with fibrosis in the bone marrow and extramedullary hematopoiesis (cell production outside the marrow). Based on these abnormalities, they are classified as

Essential thrombocythemia, primary myelofibrosis, and polycythemia vera can spontaneously transform to acute leukemia Acute leukemias Leukemia is a malignant condition involving the excess production of immature or abnormal leukocytes, which eventually suppresses the production of normal blood cells and results in symptoms... read more . Essential thrombocythemia and polycythemia vera transform at very low rates in the absence of prolonged exposure to chemotherapeutic agents such as hydroxyurea.

Each disorder is identified according to its predominant features (see table Classification of Myeloproliferative Neoplasms Classification of Myeloproliferative Neoplasms Classification of Myeloproliferative Neoplasms ). Although proliferation of one or more hematopoietic cell types dominates the clinical picture in each of these disorders, all three are caused by clonal proliferation of a pluripotent hematopoietic stem cell, causing an increased proliferation of normal RBC, WBC, and platelet progenitors in the bone marrow. This abnormal clone does not, however, produce bone marrow fibroblasts, which can proliferate in a polyclonal, reactive, and reversible fashion in response to the abnormal stem cell.

Overlap in of clinical and laboratory findings occurs because of a common etiology. Mutations of the Janus kinase 2 (JAK2) gene are responsible for polycythemia vera and a high proportion of cases of essential thrombocythemia and primary myelofibrosis. Janus kinase 2 is a member of the type I tyrosine kinase family of enzymes and is involved in signal transduction for the erythropoietin, thrombopoietin, and granulocyte colony-stimulating factor (G-CSF) receptors. The thrombopoietin receptor gene (MPL) or the calreticulin (CALR) gene is also mutated in a significant proportion of essential thrombocythemia and primary myelofibrosis patients and rarely in polycythemia vera Polycythemia Vera Polycythemia vera is a chronic myeloproliferative neoplasm characterized by an increase in morphologically normal red cells (its hallmark), but also white cells and platelets. Ten to 15% of... read more .

More Information

Tremblay D, Yacoub A, Hoffman R: Overview of myeloproliferative neoplasms. Hematol Oncol Clin N Am 35 :159-176, 2021. doi: 10.1016/j.hoc.2020.12.001

Drugs Mentioned In This Article

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HYDREA
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