Questions and Answers
Which genetic mutations are commonly associated with myeloproliferative neoplasms (MPNs)?
What is a common pathogenetic mechanism noted in myeloproliferative neoplasms?
Which of the following is NOT a characteristic of essential thrombocythemia (ET)?
Which factor is included in the WHO diagnostic criteria for primary myelofibrosis (PMF)?
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What is a significant clinical feature of primary myelofibrosis?
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What is a recommended treatment option for essential thrombocythemia (ET)?
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Which of the following disorders can myeloproliferative neoplasms evolve into?
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Which underlying mechanism is responsible for the clonal abnormalities observed in myeloproliferative neoplasms?
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What is the significance of the BCR-ABL fusion gene in relation to myeloproliferative neoplasms?
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Which of the following is NOT a major criterion for the diagnosis of primary myelofibrosis (PMF)?
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What clinical symptom is commonly associated with massive splenomegaly in primary myelofibrosis?
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Which treatment is primarily used to control platelet count in myeloproliferative neoplasms?
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What is the percentage of cases in which JAK2 mutation analysis is positive in myeloproliferative neoplasms?
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What combination of criteria is required for a diagnosis of essential thrombocythemia (ET)?
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Which of the following is NOT a cause of reactive thrombocytosis?
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Which symptom is specifically classified in the vasomotor clinical features of ET?
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In diagnosing essential thrombocythemia, which mutation's presence is considered a major criterion?
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Which of the following best describes the laboratory finding in blood films of patients with ET?
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Which is a thrombosis-related clinical feature associated with essential thrombocythemia?
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What is the role of bone marrow biopsy in diagnosing essential thrombocythemia?
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Which treatment option is generally utilized in cases of essential thrombocythemia?
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Which finding would be indicative of a myeloproliferative neoplasm rather than essential thrombocythemia?
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What mutation is commonly associated with essential thrombocythemia?
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Which of the following is considered a primary cause of absolute polycythemia?
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What is the most common myeloproliferative neoplasm (MPN)?
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At what median age is essential thrombocythemia (ET) commonly diagnosed?
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Which of the following is NOT a cause of inappropriate increase in erythropoietin?
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Polycythemia vera (PV) is defined as an increase in which of the following?
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What is a clinical feature of primary myelofibrosis (PMF)?
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Which of the following conditions is most likely to cause relative polycythemia?
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JAK2 mutations are primarily associated with which type of hematologic disorder?
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What is a common feature of essential thrombocythemia regarding gender distribution?
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Study Notes
Myeloproliferative Neoplasms (MPNs)
- MPNs stem from acquired clonal abnormalities of hematopoietic stem cells, affecting myeloid, erythroid, and platelet lineages.
- Constitutive tyrosine kinase activation is a common pathogenic mechanism across MPNs.
- The Philadelphia chromosome is a notable cytogenetic abnormality in chronic myeloid leukemia (CML).
- Key genetic mutations include JAK2, MPL, CALR, and CSF3R.
JAK2 Gene
- The JAK2 gene encodes a protein that promotes cell growth and proliferation, particularly within the JAK/STAT signaling pathway.
- JAK2 plays a crucial role in blood cell production from hematopoietic stem cells.
WHO Classification of MPNs
- Essential thrombocythemia (ET) and primary myelofibrosis (PMF) are significant classifications under MPNs.
Essential Thrombocythemia (ET) Diagnostic Criteria
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Major Criteria:
- Platelet count ≥ 450 x 10⁹/L
- Bone marrow biopsy shows proliferation mainly of megakaryocytes, with no significant increase in other lineages.
- Absence of BCR-ABL-1 CML, polycythemia vera (PV), PMF, or myelodysplastic syndromes.
- Presence of JAK2, CALR, or MPL mutation.
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Minor Criteria:
- Clonal marker presence or absence of reactive thrombocytosis.
- Diagnosis requires all major criteria or first three major criteria plus one minor criterion.
Causes of Polycythemia
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Absolute Polycythemia:
- Primary: Polycythemia vera (PV).
- Secondary causes include appropriate and inappropriate erythropoietin increases due to various conditions (e.g., pulmonary diseases, renal diseases).
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Relative/Pseudo Polycythemia:
- Normal red cell mass but reduced plasma volume, often due to dehydration or plasma loss.
Reactive Thrombocytosis Causes
- Iron deficiency, blood loss, hyposplenism, surgery, chronic inflammation, malignancies, and rebound thrombocytosis after ITP or chemotherapy.
Clinical Features of ET
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Vasomotor Symptoms:
- Headaches, visual disturbances, paresthesias, cognitive deficits, seizures.
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Thrombotic Events:
- Arterial (e.g., TIA, CVA, coronary) and venous thrombosis (e.g., deep vein thrombosis).
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Hemorrhagic Manifestations:
- Gastrointestinal bleeding, mucosal bleeding, hemarthrosis.
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Obstetric Complications:
- Spontaneous abortion, fetal growth retardation.
- Splenomegaly occurs in about 50% of patients.
Laboratory Investigations for ET
- Blood films may show large abnormal platelets and megakaryocyte fragments.
- Bone marrow biopsy exhibits hypercellularity with excess abnormal megakaryocytes.
Primary Myelofibrosis (PMF) Diagnosis
- Diagnosed with three major criteria and one minor criterion.
Clinical Features of PMF
- Insidious onset, often in older adults, with symptoms of anemia and significant splenomegaly.
- Hypermetabolic symptoms such as weight loss and fevers may also be present.
Laboratory Investigations for PMF
- Anemia is common; leukopenia and thrombocytopenia may develop later.
- Characteristic blood picture shows teardrop-shaped red blood cells.
- Bone marrow aspiration may yield dry taps; biopsy shows fibrotic hypercellular marrow.
- Elevated uric acid and LDH levels due to increased hematopoietic cell turnover.
- JAK2 mutation is positive in about 60% of cases.
Treatment of ET and PMF
- Goals focus on controlling platelet counts and minimizing thrombotic risks.
- Hydroxyurea is commonly used for controlling elevated platelet counts.
- Treatment options vary based on individual case specifics for both ET and PMF.
Prognosis
- MPNs may progress to acute myeloid leukemia (AML).
- Evolution of MPNs can lead to hybrid disorders, complicating the clinical picture and management.
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Description
Explore the essential aspects of myeloproliferative neoplasms (MPNs), including key genetic mutations and classification systems. Learn about the implications of the JAK2 gene and diagnostic criteria for conditions like essential thrombocythemia. This quiz is a great resource for understanding MPNs in hematology.
