Updated: 7/21/2020

Polycythemia Vera

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Snapshot
  • A 59-year-old woman presents to her primary care physician with overwhelming fatigue, headaches, and some blurry vision. She is worried that old age is finally catching up. While she is happy about losing 10 lbs over the past month, she is also confused since she has not changed her diet or exercise routine. On further questioning, she reveals that she is extremely itchy after a hot bath or shower. She is otherwise healthy. A blood smear shows RBC precursors.
Introduction
  • Myeloproliferative neoplasm characterized by increased production of RBCs
    • leads to highly viscous blood
  • Epidemiology
    • presentation in those aged 60-70
  • Pathogenesis
    • mutations in JAK2 (Janus kinase) 
      • V617F mutation
      • constitutively active Janus kinase unregulated myeloproliferation
    • erythrocytosis ↑ blood viscosity
    • leukocytosis
    • thrombocytosis
  • Associated conditions
    • risk of progression to myelofibrosis or leukemia
    • Budd-Chiari syndrome 
      • caused by occlusion of IVC or hepatic veins leading to congestive liver disease
  • Prognosis
    • 1.6x higher mortality than general population
Presentation
  • Symptoms
    • headaches
    • visual disturbance
    • bleeding
      • caused by engorged vessels
    • constitutional symptoms
      • fatigue
      • night sweats
      • weight loss
      • fever
      • malaise
    • pruritus
      • caused by histamine release from increased basophils
      • often triggered by hot shower or bath
  • Physical exam
    • erythromelalgia (rare but classic)  
      • caused by thrombosis
      • characterized by painful burning sensation with increased temperatures in digits and episodic blood clots in extremities
    • hepatosplenomegaly
    • bruising
    • ischemic digits
    • large retinal veins on funduscopy
Evaluation
  • Labs
    • complete blood count with smear will show
      • ↑ hemoglobin > 16 g/dL (females) or > 16.5 g/dL (males)
      • ↑ hct > 48% (F) or > 49% (M)
    • JAK2 mutation in peripheral blood
    • ↓ serum EPO 
      • ↑ RBC despite low EPO
      • if EPO is high, consider ectopic EPO production (e.g., in renal cell carcinoma)
    • ↓ MCV
    • SaO2 normal
  • Bone marrow biopsy 
    • shows hypercellularity and prominent proliferation of all cell lines
      • commonly see precursor cells
    • used to confirm diagnosis
    • used as a baseline for assessing disease progression
Differential Diagnosis
  • Secondary polycythemia
    • key distinguishing factors
      • volume depletion will also present with increased BUN/creatinine ratio 
  • Tumor-driven polycythemia
  • Other myeloproliferative neoplasm
Treatment
  • Reduce risk of thrombosis
    • low-dose aspirin
    • phlebotomy
      • indicated for a hematocrit < 45%
  • Myelosuppression
    • hydroxyurea
  • Gout prophylaxis
    • allopurinol
Complications
  • Thrombosis
    • leading cause of morbidity and mortality
  • Peptic ulcers
    • increased histamine release from basophils
  • Gout
    • increased uric acid from high number of cell turnover
  • Progression to
    • myelofibrosis 
    • CML 
    • AML 
 

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Questions (3)

(M1.ON.17.4798) A 66-year-old male with a history of diabetes and knee osteoarthritis presents to his primary care provider in July complaining of headaches and blurry vision. He reports a 6-month history of occasional dull diffuse headaches and blurry vision. He notes that the episodes have increased in severity since the weather got warmer and that he occasionally feels extremely itchy when he spends time outdoors. The patient lives in southern Arizona. Moreover, he has felt chronically fatigued and has lost 10 pounds without dieting or changing his appetite. He currently takes metformin and his most recent hemoglobin A1c was 6.5%. Physical examination reveals multiple bruises on the bilateral upper and lower extremities and hepatosplenomegaly. Fundoscopic examination demonstrates enlarged retinal veins. Multiple laboratory tests are pending. At steady state, which of the following sets of findings is most likely in this patient? Tested Concept

QID: 109194
1

Increased plasma volume, increased RBC mass, decreased EPO, normal SaO2

44%

(44/101)

2

Normal plasma volume, increased RBC mass, increased EPO, normal SaO2

19%

(19/101)

3

Decreased plasma volume, normal RBC mass, normal EPO, normal SaO2

12%

(12/101)

4

Normal plasma volume, increased RBC mass, increased EPO, decreased SaO2

17%

(17/101)

5

Increased plasma volume, decreased RBC mass, decreased EPO, normal SaO2

5%

(5/101)

M 1 B

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(M1.ON.15.75) A 56-year-old man presents to his primary care physician endorsing fatigue, episodic pruritus, and headaches. These symptoms have been occurring for the last 1-2 months but have gotten progressively worse over time. His wife has noticed a new "ruddy" color to his skin that has developed during this period. He is otherwise healthy, with no medical problems. On examination, the patient appears fatigued and plethoric. A complete blood cell count reveals a hematocrit of 59% with no other abnormalities. A peripheral blood smear is shown in Figure A. Mutation in which of the following genes is responsible for the patient's condition? Tested Concept

QID: 106754
FIGURES:
1

BCR-ABL

10%

(13/124)

2

RET

6%

(8/124)

3

p53

7%

(9/124)

4

JAK2

71%

(88/124)

5

FLT3

3%

(4/124)

M 1 D

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Evidences (4)
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Topic COMMENTS (20)
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