Essential thrombocythemia

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Essential thrombocythemia
Other namesEssential thrombocythaemia, essential thrombocytosis, primary thrombocytosis
Low-dose aspirin, plateletpheresis, cytoreductive therapy.[1]
PrognosisMedian survival is 18 years.[1]
Frequency0.6-2.5/100,000 cases per year.[2]

In

red blood cells, or platelets.[3]

Signs and symptoms

Most people with essential thrombocythemia are

reduced red blood cell count, and an enlarged spleen.[4][5][6]

Cause

In ET,

JAK2 kinase (V617F) is present in 40–50% of cases and is diagnostic if present.[3][8] JAK2 is a member of the Janus kinase family.[3][8]

In 2013, two groups detected

KDEL retention signal.[9][10]

Diagnosis

The following revised diagnostic criteria for essential thrombocythemia were proposed in 2005.[11] The diagnosis requires the presence of both A criteria together with B3 to B6, or of criterion A1 together with B1 to B6.[12] The criteria are as follows:[12]

  • A1.
    Platelet count
    > 400 × 103/µL for at least 2 months.
  • A2. Acquired V617F
    JAK2
    mutation present
  • B1. No cause for a reactive thrombocytosis
    • normal inflammatory indices
  • B2. No evidence of iron deficiency
    • stainable iron in the bone marrow or normal red cell mean corpuscular volume
  • B3. No evidence of polycythemia vera
    • hematocrit < midpoint of normal range or normal red cell mass in presence of normal iron stores
  • B4. No evidence of
    chronic myeloid leukemia
    • But the
      acute lymphocytic leukemia
      .
  • B5. No evidence of
    myelofibrosis
    • no collagen fibrosis and ≤ grade 2 reticulin fibrosis (using 0–4 scale)
  • B6. No evidence of a myelodysplastic syndrome
    • no significant dysplasia
    • no cytogenetic abnormalities suggestive of
      myelodysplasia

Treatment

Indications

Not all those affected will require treatment at presentation.

interferon-α or anagrelide).[3][13][14][15] Currently unapproved but in late-stage clinical trials (NCT04254978) are agents that lower platelets such as bomedemstat
.

Agents

interferon-α and anagrelide can lower the platelet count. Low-dose aspirin is used to reduce the risk of blood clot formation unless the platelet count is very high, where there is a risk of bleeding from the disease, and hence this measure would be counter-productive as aspirin-use increases the risk of bleeding.[3][13][14][15]

The PT1 study compared hydroxyurea plus aspirin to anagrelide plus aspirin as initial therapy for ET. Hydroxyurea treated patients had a lower incidence of arterial thrombosis, lower incidence of severe bleeding and lower incidence of transformation to myelofibrosis, but the risk of venous thrombosis was higher with hydroxycarbamide than with anagrelide. It is unknown whether the results are applicable to all ET patients.[3][13][14][15] In people with symptomatic ET and extremely high platelet counts (exceeding 1 million), plateletpheresis can be used to remove platelets from the blood to reduce the risk of thrombosis.[16]

Prognosis

Essential thrombocythemia is sometimes described as a slowly progressive disorder with long asymptomatic periods punctuated by thrombotic or hemorrhagic events.[13] However, well-documented medical regimens can reduce and control the number of platelets, which reduces the risk of these thrombotic or hemorrhagic events. The lifespan of a well-controlled ET person is well within the expected range for a person of similar age but without ET.[13] ET is the myeloproliferative neoplasm least likely to progress to acute myeloid leukemia.[17]

Epidemiology

The incidence of ET is 0.6-2.5/100,000 per year, the median age at onset is 65–70 years and it is more frequent in females than in males.[2] The incidence in children is 0.09/100,000 per year.[2]

Pregnancy

enoxaparin) may be used.[18] For life-threatening complications, the platelet count can be reduced rapidly using plateletpheresis, a procedure that removes platelets from the blood and returns the remainder to the patient.[18]

In popular culture

Jill Kaplan, the female protagonist of The Pajama Diaries comic strip was diagnosed with essential thrombocythemia.[19]

References

  1. ^
    PMID 30969531
    – via PubMed.
  2. ^
    S2CID 43185338
    .
  3. ^
    PMID 20008247
    .
  4. ^
    S2CID 10880402
    .
  5. PMID 22889110
    .
  6. S2CID 205293800
    .
  7. PMID 1060175
    .
  8. ^
    S2CID 510829
    .
  9. PMID 24325359
    .
  10. S2CID 14787432
    .
  11. PMID 16304381
    .
  12. ^
    S2CID 3101472.[permanent dead link
    ]
  13. ^
    S2CID 18862829
    .
  14. ^
    S2CID 11357000
    .
  15. ^
    PMID 23558521
    .
  16. PMID 28380402
    .
  17. ^ "Essential Thrombocythemia". The Lecturio Medical Concept Library. Retrieved 22 July 2021.
  18. ^
    PMID 21640467
    .
  19. ^ "The Pajama Diaries".

External links

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