Essential thrombocythemia

From IDWiki

Definition

Clinical Manifestations

  • History
    • History of thrombosis or bleeding
  • Signs & Symptoms
    • Digital ischemia
    • Cerebrovascular ischemia
  • High risk for vascular events if:
    • History of thrombosis or bleeding
    • Increased cardiovascular risk
    • Older than 60 years

Differential Diagnosis

Investigations

  • CBC with peripheral blood film shows thrombocytosis with platelet anisocytosis
  • Bone marrow aspiration and biopsy shows normal cellularity or moderate hypercellularity with large megakaryocytes
    • Findings that suggest an alternative diagnosis include highly atypical megakaryocytes, increased myeloblasts, myelodysplastic features, or significant reticulin fibrosis or collagen fibrosis
  • Genetic testing
    • JAK2 in 60-65%
    • CALR in 20-25%
    • MPL in 5%
    • Triple-negative (all above negative) in 10-15%
  • Send BCR-ABL testing to exclude CML

WHO Diagnostic Criteria

  • Diagnosis require 4 major criteria or the first 3 major criteria plus the minor criterion
  • Major criteria
    • Platelets ≥450
    • Bone marrow biopsy showing proliferation of megakaryocytes with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei; and no significant increase or left shift in neutrophil granulopoiesis or erythropoiesis and very rare minor increase in reticulin fibers
    • Not meeting WHO criteria for BCR-ABL1 CML, PV, PMF, myelodysplastic syndrome, or other myeloid neoplasms
    • Presence of JAK2, CALR, or MPL mutation
  • Minor criterion
    • Presence of a clonal marker or abscence of evidence for reactive thrombocytosis

Management

  • Acute
    • If digital or cerebrovascular ischemia, rapid cytoreduction with platelet pheresis
  • Chronic