Merck Manual

Please confirm that you are a health care professional

honeypot link

Overview of Myeloproliferative Neoplasms

By

Jane Liesveld

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

Last full review/revision Sep 2020| Content last modified Sep 2020
Click here for Patient Education
Topic Resources

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) in the circulation and sometimes as increased fibrosis in the bone marrow with consequent extramedullary hematopoiesis (cell production outside the marrow). Based on these abnormalities, they are classified as

Essential thrombocythemia, primary myelofibrosis, and polycythemia vera are Philadelphia chromosome–negative myeloproliferative neoplasms that 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.

Each disorder is identified according to its predominant features (see table Classification of Myeloproliferative Neoplasms Classification of Myeloproliferative Neoplasms 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)... read more ). Overlap in of clinical and laboratory findings occurs because essential thrombocythemia. primary myelofibrosis, and polycythemia vera can have driver mutations that constitutively activate Janus kinase 2 (JAK2). 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 fashion in response to the abnormal stem cell.

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 tyrosine kinase family of enzymes and is involved in signal transduction for erythropoietin, thrombopoietin, and granulocyte colony-stimulating factor (G-CSF) among other entities. 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 (PV) is a chronic myeloproliferative neoplasm characterized by an increase in morphologically normal red cells (its hallmark), but also white cells and platelets. Ten to 30%... read more .

Table
icon
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read
Test your knowledge
Langerhans Cell Histiocytosis
A 10-year-old girl is brought to the clinic by her father because she has had pain in her right upper leg for the past 3 months. On physical examination, the patient is unable to bear weight on the limb. Edema of the upper leg and tenderness to palpation are noted. X-rays show 2 bone lesions with sharp margins and a punched-out appearance. Which of the following is the most appropriate definitive step in diagnosis?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP