Medical Importance
The chronic myeloproliferative diseases are clonal hematopoietic
stem cell disorders in which the progenitor cells of one or more of the
hematopoietic lineages proliferate excessively. In contrast to the
situation in myelodysplastic syndromes and acute leukemia (in which the
hematopoietic precursor cells do not undergo terminal differentiation),
cellular differentiation from immature precursor cells to mature blood
cells proceeds in a normal manner. Consequently, mature leukocytes, red
cells, and platelets are overproduced in patients with these diseases
and generally at least one of the blood cell counts is high. Some
patients with a myeloproliferative disorder can present with seemingly
trivial symptoms, and in others the diagnoses is made during or after a
life-threatening complication. Symptoms can include itching, burning
feet, bleeding, or thrombosis. Effective treatment can minimize
symptoms and prevent major debilitating complications, but these
diseases are incurable unless the neoplastic clone is destroyed and
replaced by normal hematopoietic stem cells.
Objectives
- Name the four major myeloproliferative disorders and describe the pathophysiologic features shared by these disorders.
- Name four causes of reactive or secondary thrombocytosis.
- Name the two major complications of essential thrombocythemia.
- Describe the typical physical exam, and blood and bone marrow findings in patients with chronic idiopathic myelofibrosis.
- Describe the common mutation associated with polycythemia vera and its biological consequences.
- Describe the clinical features and complications of polycythemia vera.
- Describe treatment approaches to polycythemia vera.
- Name three causes of splenomegaly.
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