Essential thrombocythemia vs Reactive thrombocytosis
How to tell Essential thrombocythemia and Reactive thrombocytosis apart when a board question makes them look alike.
ET is clonal persistent thrombocytosis with JAK2/CALR/MPL; reactive thrombocytosis is a secondary response to another condition.
Side by side
Essential thrombocythemia is clonal platelet overproduction with persistent thrombocytosis, large atypical megakaryocytes, JAK2/CALR/MPL mutations, thrombosis, erythromelalgia, or bleeding from acquired vWF dysfunction.
Reactive thrombocytosis is secondary platelet elevation from infection, inflammation, iron deficiency, malignancy, surgery, trauma, hemolysis, or asplenia.
A myeloproliferative clone expands megakaryocytes and produces excess platelets that can be quantitatively high but functionally abnormal.
Inflammatory cytokines, iron deficiency, or tissue stress drive thrombopoietic response without a primary myeloid clone.
Persistent platelets above 450,000/uL, clonal mutation, megakaryocytic hyperplasia, low inflammatory trigger burden, and abnormal platelet symptoms support essential thrombocythemia.
Elevated CRP/ESR, infection or inflammation, iron deficiency, recent surgery, or splenectomy history with no clonal marker supports reactive thrombocytosis.
The trap
A high platelet count alone does not prove ET; persistence, clonal markers, marrow, and clinical trigger decide.
Watch it explained
The repair move
For thrombocytosis, look for a reactive trigger first, then clonal markers and marrow pattern.
Try a free question
CoreA patient has persistent platelets above 900,000/uL, headaches, erythromelalgia, prior thrombosis, JAK2 mutation, and marrow megakaryocytic hyperplasia. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Essential thrombocythemia. Persistent clonal thrombocytosis with JAK2 mutation and thrombotic symptoms points to essential thrombocythemia.
Why the other choices are tempting
- B. Reactive thrombocytosis should have an underlying trigger and no clonal marker.
- C. Polycythemia vera is erythrocytosis-predominant.
- D. CML is BCR-ABL granulocytic proliferation.
- E. ITP causes low platelets, not persistent thrombocytosis.
Flashcards
Tap a card to flip it.
What mutations support essential thrombocythemia?
JAK2, CALR, or MPL mutations support essential thrombocythemia.
What symptom clue supports essential thrombocythemia?
Erythromelalgia or thrombosis with persistent thrombocytosis supports essential thrombocythemia.
Quick answers
What is the fastest way to tell Essential thrombocythemia from Reactive thrombocytosis?
ET is clonal persistent thrombocytosis with JAK2/CALR/MPL; reactive thrombocytosis is a secondary response to another condition.
What is the key clue for Essential thrombocythemia?
Essential thrombocythemia is clonal platelet overproduction with persistent thrombocytosis, large atypical megakaryocytes, JAK2/CALR/MPL mutations, thrombosis, erythromelalgia, or bleeding from acquired vWF dysfunction.
What is the key clue for Reactive thrombocytosis?
Reactive thrombocytosis is secondary platelet elevation from infection, inflammation, iron deficiency, malignancy, surgery, trauma, hemolysis, or asplenia.
What is the common trap with Essential thrombocythemia vs Reactive thrombocytosis?
A high platelet count alone does not prove ET; persistence, clonal markers, marrow, and clinical trigger decide.