Essential thrombocythemia (ET) is a clonal myeloproliferative neoplasm characterized by sustained megakaryocyte proliferation leading to elevated platelet counts. Driver mutations include JAK2 V617F (approximately 55%), CALR (25%), and MPL (3%), with 15% being triple-negative. ET has the most indolent course among classic myeloproliferative neoplasms with near-normal life expectancy in younger patients, though it carries risks of thrombosis, hemorrhage, and transformation to myelofibrosis or acute leukemia. Treatment focuses on thrombosis prevention with aspirin and cytoreduction in high-risk patients using hydroxyurea, anagrelide, or interferon.
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name: Essential Thrombocythemia
creation_date: '2026-01-26T02:55:13Z'
updated_date: '2026-05-01T12:00:00Z'
description: >-
Essential thrombocythemia (ET) is a clonal myeloproliferative neoplasm characterized
by sustained megakaryocyte proliferation leading to elevated platelet counts.
Driver mutations include JAK2 V617F (approximately 55%), CALR (25%), and MPL (3%),
with 15% being triple-negative. ET has the most indolent course among classic
myeloproliferative neoplasms with near-normal life expectancy in younger patients,
though it carries risks of thrombosis, hemorrhage, and transformation to myelofibrosis
or acute leukemia. Treatment focuses on thrombosis prevention with aspirin and
cytoreduction in high-risk patients using hydroxyurea, anagrelide, or interferon.
categories:
- Hematologic Malignancy
- Myeloproliferative Neoplasm
parents:
- myeloproliferative neoplasm
pathophysiology:
- name: JAK-STAT Pathway Hyperactivation
description: >-
Driver mutations in JAK2, CALR, or MPL converge on constitutive JAK-STAT
signaling activation. JAK2 V617F directly activates the kinase; CALR mutations
cause aberrant activation of MPL receptor; MPL mutations cause constitutive
thrombopoietin receptor activation.
evidence:
- reference: PMID:41577837
reference_title: "Diagnostic reassessment in myeloproliferative neoplasms: the value of functional iron parameters and JAK2 allelic burden."
supports: PARTIAL
snippet: "Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms (MPNs), often associated with mutations in JAK2, CALR, and MPL."
explanation: This abstract links ET to JAK2/CALR/MPL mutations, supporting the JAK-STAT activation described.
cell_types:
- preferred_term: megakaryocyte
term:
id: CL:0000556
label: megakaryocyte
biological_processes:
- preferred_term: JAK-STAT signaling pathway
modifier: INCREASED
term:
id: GO:0007259
label: cell surface receptor signaling pathway via JAK-STAT
locations:
- preferred_term: bone marrow
term:
id: UBERON:0002371
label: bone marrow
downstream:
- target: Enhanced Megakaryopoiesis
description: JAK-STAT activation drives megakaryocyte proliferation and platelet production
- name: Enhanced Megakaryopoiesis
description: >-
Constitutive JAK-STAT signaling drives increased megakaryocyte proliferation
and maturation. Unlike myelofibrosis, megakaryocytes in ET are large and
mature without significant atypia or clustering.
biological_processes:
- preferred_term: megakaryocyte differentiation
modifier: INCREASED
term:
id: GO:0030219
label: megakaryocyte differentiation
downstream:
- target: Platelet Dysfunction and Thrombosis Risk
description: Elevated platelet production leads to platelet dysfunction and thrombotic/hemorrhagic complications
- name: Platelet Dysfunction and Thrombosis Risk
description: >-
Despite elevated platelet counts, thrombosis risk is multifactorial and
involves platelet activation, leukocyte-platelet interactions, and
endothelial dysfunction. Paradoxically, extreme thrombocytosis (>1,000,000/uL)
may cause acquired von Willebrand disease and bleeding.
biological_processes:
- preferred_term: platelet activation
modifier: ABNORMAL
term:
id: GO:0030168
label: platelet activation
histopathology:
- name: Megakaryocytic Proliferation
finding_term:
preferred_term: Megakaryocyte Proliferation
term:
id: NCIT:C19919
label: Megakaryocyte Proliferation
frequency: VERY_FREQUENT
description: Essential thrombocythemia is characterized by thrombocytosis.
evidence:
- reference: PMID:30969531
reference_title: "Essential Thrombocytosis."
supports: PARTIAL
snippet: "ET is characterized by thrombocytosis"
explanation: Abstract notes ET is characterized by thrombocytosis.
phenotypes:
- category: Hematologic
name: Thrombocytosis
frequency: VERY_FREQUENT
diagnostic: true
description: >-
Persistent platelet count of 450,000/uL or greater is a diagnostic criterion.
Many patients have counts exceeding 1,000,000/uL at diagnosis.
phenotype_term:
preferred_term: Thrombocytosis
term:
id: HP:0001894
label: Thrombocytosis
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0001894 | Thrombocytosis | Very frequent (99-80%)"
explanation: Orphanet classifies thrombocytosis as very frequent in ET.
- category: Hematologic
name: Abnormal Platelet Morphology
frequency: VERY_FREQUENT
description: >-
Giant platelets and abnormal platelet granulation are characteristic
findings on peripheral blood smear.
phenotype_term:
preferred_term: Abnormal platelet morphology
term:
id: HP:0011875
label: Abnormal platelet morphology
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0011875 | Abnormal platelet morphology | Very frequent (99-80%)"
explanation: Orphanet classifies abnormal platelet morphology as very frequent.
- category: Hematologic
name: Increased Megakaryocyte Count
frequency: VERY_FREQUENT
description: >-
Bone marrow biopsy shows markedly increased megakaryocytes that are large
and mature with hyperlobulated nuclei.
phenotype_term:
preferred_term: Increased megakaryocyte count
term:
id: HP:0005513
label: Increased megakaryocyte count
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0005513 | Increased megakaryocyte count | Very frequent (99-80%)"
explanation: Orphanet classifies increased megakaryocyte count as very frequent.
- category: Hematologic
name: Megakaryocyte Nucleus Hyperlobulation
frequency: VERY_FREQUENT
description: >-
Megakaryocytes in ET characteristically show hyperlobulated nuclei, a
key histologic feature distinguishing ET from prefibrotic myelofibrosis.
phenotype_term:
preferred_term: Megakaryocyte nucleus hyperlobulation
term:
id: HP:0031388
label: Megakaryocyte nucleus hyperlobulation
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0031388 | Megakaryocyte nucleus hyperlobulation | Very frequent (99-80%)"
explanation: Orphanet classifies megakaryocyte nucleus hyperlobulation as very frequent.
- category: Hematologic
name: Prolonged Bleeding Time
frequency: VERY_FREQUENT
description: >-
Prolonged bleeding time reflects platelet dysfunction despite elevated counts,
particularly in patients with extreme thrombocytosis and acquired von Willebrand disease.
phenotype_term:
preferred_term: Prolonged bleeding time
term:
id: HP:0003010
label: Prolonged bleeding time
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0003010 | Prolonged bleeding time | Very frequent (99-80%)"
explanation: Orphanet classifies prolonged bleeding time as very frequent.
- category: Hematologic
name: Abnormal Bleeding
frequency: FREQUENT
description: >-
Hemorrhagic complications include gastrointestinal bleeding, epistaxis, and
easy bruising, particularly in those with extreme thrombocytosis.
phenotype_term:
preferred_term: Abnormal bleeding
term:
id: HP:0001892
label: Abnormal bleeding
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0001892 | Abnormal bleeding | Frequent (79-30%)"
explanation: Orphanet classifies abnormal bleeding as frequent.
- category: Hematologic
name: Bruising Susceptibility
frequency: OCCASIONAL
description: >-
Easy bruising due to platelet dysfunction.
phenotype_term:
preferred_term: Bruising susceptibility
term:
id: HP:0000978
label: Bruising susceptibility
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0000978 | Bruising susceptibility | Occasional (29-5%)"
explanation: Orphanet classifies bruising susceptibility as occasional.
- category: Hematologic
name: Leukocytosis
frequency: OCCASIONAL
description: >-
Mild leukocytosis may be present in a subset of patients, particularly those
with JAK2 V617F mutations.
phenotype_term:
preferred_term: Leukocytosis
term:
id: HP:0001974
label: Increased total leukocyte count
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0001974 | Leukocytosis | Occasional (29-5%)"
explanation: Orphanet classifies leukocytosis as occasional.
- category: Hematologic
name: Abnormal Bone Marrow Cell Morphology
frequency: VERY_FREQUENT
description: >-
Bone marrow cellularity and architecture are abnormal, with megakaryocytic
hyperplasia, loose clustering of enlarged megakaryocytes, and characteristic
absence of significant reticulin fibrosis distinguishing ET from prefibrotic myelofibrosis.
phenotype_term:
preferred_term: Abnormal bone marrow cell morphology
term:
id: HP:0005561
label: Abnormal bone marrow cell morphology
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0005561 | Abnormality of bone marrow cell morphology | Very frequent (99-80%)"
explanation: Orphanet classifies abnormality of bone marrow cell morphology as very frequent.
- category: Vascular
name: Abnormal Cerebral Vascular Morphology
frequency: VERY_FREQUENT
description: >-
Cerebrovascular abnormalities reflecting platelet-mediated microthrombotic
and macrothrombotic events in cerebral vessels, contributing to stroke and
TIA risk.
phenotype_term:
preferred_term: Abnormal cerebral vascular morphology
term:
id: HP:0100659
label: Abnormal cerebral vascular morphology
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0100659 | Abnormality of the cerebral vasculature | Very frequent (99-80%)"
explanation: Orphanet classifies abnormality of the cerebral vasculature as very frequent.
- category: Vascular
name: Arterial Thrombosis
frequency: VERY_FREQUENT
description: >-
Arterial thrombotic events are the major complication, including stroke,
myocardial infarction, and peripheral arterial occlusion.
phenotype_term:
preferred_term: Arterial thrombosis
term:
id: HP:0004420
label: Arterial thrombosis
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0004420 | Arterial thrombosis | Very frequent (99-80%)"
explanation: Orphanet classifies arterial thrombosis as very frequent.
- category: Vascular
name: Venous Thrombosis
frequency: VERY_FREQUENT
description: >-
Venous thromboembolism including deep vein thrombosis, pulmonary embolism,
and splanchnic vein thrombosis.
phenotype_term:
preferred_term: Venous thrombosis
term:
id: HP:0004936
label: Venous thrombosis
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0004936 | Venous thrombosis | Very frequent (99-80%)"
explanation: Orphanet classifies venous thrombosis as very frequent.
- category: Vascular
name: Myocardial Infarction
frequency: VERY_FREQUENT
description: >-
Myocardial infarction is a major arterial thrombotic complication of ET.
phenotype_term:
preferred_term: Myocardial infarction
term:
id: HP:0001658
label: Myocardial infarction
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0001658 | Myocardial infarction | Very frequent (99-80%)"
explanation: Orphanet classifies myocardial infarction as very frequent.
- category: Vascular
name: Hepatic Vein Thrombosis
frequency: OCCASIONAL
description: >-
Budd-Chiari syndrome due to hepatic vein thrombosis is a recognized
complication, particularly in younger patients with JAK2 mutations.
phenotype_term:
preferred_term: Hepatic vein thrombosis
term:
id: HP:0030243
label: Hepatic vein thrombosis
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0030243 | Hepatic vein thrombosis | Occasional (29-5%)"
explanation: Orphanet classifies hepatic vein thrombosis as occasional.
- category: Vascular
name: Transient Ischemic Attack
frequency: OCCASIONAL
description: >-
Transient ischemic attacks reflect cerebrovascular microthrombotic events.
phenotype_term:
preferred_term: Transient ischemic attack
term:
id: HP:0002326
label: Transient ischemic attack
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002326 | Transient ischemic attack | Occasional (29-5%)"
explanation: Orphanet classifies transient ischemic attack as occasional.
- category: Vascular
name: Amaurosis Fugax
frequency: VERY_FREQUENT
description: >-
Transient monocular visual loss due to platelet-mediated microthrombi
in the retinal vasculature.
phenotype_term:
preferred_term: Amaurosis fugax
term:
id: HP:0100576
label: Amaurosis fugax
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0100576 | Amaurosis fugax | Very frequent (99-80%)"
explanation: Orphanet classifies amaurosis fugax as very frequent.
- category: Vascular
name: Chest Pain
frequency: VERY_FREQUENT
description: >-
Chest pain may reflect microvascular ischemia or coronary thrombosis.
phenotype_term:
preferred_term: Chest pain
term:
id: HP:0100749
label: Chest pain
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0100749 | Chest pain | Very frequent (99-80%)"
explanation: Orphanet classifies chest pain as very frequent.
- category: Vascular
name: Erythromelalgia
frequency: OCCASIONAL
description: >-
Burning pain, redness, and warmth in extremities due to platelet-mediated
arteriolar inflammation. Highly responsive to aspirin therapy.
phenotype_term:
preferred_term: Erythromelalgia
term:
id: HP:0032147
label: Erythromelalgia
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0032147 | Erythromelalgia | Occasional (29-5%)"
explanation: Orphanet classifies erythromelalgia as occasional.
- category: Neurological
name: Paresthesia
frequency: VERY_FREQUENT
description: >-
Acral paresthesias (tingling, numbness in fingers and toes) are among the
most common microvascular symptoms in ET.
phenotype_term:
preferred_term: Paresthesia
term:
id: HP:0003401
label: Paresthesia
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0003401 | Paresthesia | Very frequent (99-80%)"
explanation: Orphanet classifies paresthesia as very frequent.
- category: Neurological
name: Headache
frequency: FREQUENT
description: >-
Headaches are common and may reflect microvascular disturbance.
Erythromelalgia-associated headache responds well to aspirin.
phenotype_term:
preferred_term: Headache
term:
id: HP:0002315
label: Headache
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002315 | Headache | Frequent (79-30%)"
explanation: Orphanet classifies headache as frequent.
- category: Neurological
name: Migraine
frequency: FREQUENT
description: >-
Migraine headaches may be triggered by platelet-mediated microvascular ischemia.
phenotype_term:
preferred_term: Migraine
term:
id: HP:0002076
label: Migraine
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002076 | Migraine | Frequent (79-30%)"
explanation: Orphanet classifies migraine as frequent.
- category: Neurological
name: Vertigo
frequency: FREQUENT
description: >-
Vertigo and dizziness reflect cerebrovascular microcirculatory disturbance.
phenotype_term:
preferred_term: Vertigo
term:
id: HP:0002321
label: Vertigo
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002321 | Vertigo | Frequent (79-30%)"
explanation: Orphanet classifies vertigo as frequent.
- category: Neurological
name: Visual Impairment
frequency: OCCASIONAL
description: >-
Visual disturbances due to microvascular occlusion in the retinal circulation.
phenotype_term:
preferred_term: Visual impairment
term:
id: HP:0000505
label: Visual impairment
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0000505 | Visual impairment | Occasional (29-5%)"
explanation: Orphanet classifies visual impairment as occasional.
- category: Abdominal
name: Splenomegaly
frequency: FREQUENT
description: >-
Splenomegaly is present in a significant proportion of patients. Marked
splenomegaly suggests possible transformation to myelofibrosis.
phenotype_term:
preferred_term: Splenomegaly
term:
id: HP:0001744
label: Splenomegaly
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0001744 | Splenomegaly | Frequent (79-30%)"
explanation: Orphanet classifies splenomegaly as frequent.
- category: Constitutional
name: Fatigue
frequency: VERY_FREQUENT
description: >-
Fatigue and reduced quality of life are common despite the generally
indolent disease course.
phenotype_term:
preferred_term: Fatigue
term:
id: HP:0012378
label: Fatigue
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0012378 | Fatigue | Very frequent (99-80%)"
explanation: Orphanet classifies fatigue as very frequent.
- category: Constitutional
name: Insomnia
frequency: FREQUENT
description: >-
Sleep disturbance contributes to reduced quality of life in ET patients.
phenotype_term:
preferred_term: Insomnia
term:
id: HP:0100785
label: Insomnia
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0100785 | Insomnia | Frequent (79-30%)"
explanation: Orphanet classifies insomnia as frequent.
- category: Disease Progression
name: Myelofibrosis
frequency: OCCASIONAL
description: >-
Fibrotic transformation occurs in a subset of ET patients, particularly
those with CALR mutations and long disease duration.
phenotype_term:
preferred_term: Myelofibrosis
term:
id: HP:0011974
label: Myelofibrosis
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0011974 | Myelofibrosis | Occasional (29-5%)"
explanation: Orphanet classifies myelofibrosis as occasional.
- category: Disease Progression
name: Acute Leukemia
frequency: OCCASIONAL
description: >-
Leukemic transformation is a rare but serious complication, occurring
more frequently in patients treated with alkylating agents.
phenotype_term:
preferred_term: Acute leukemia
term:
id: HP:0002488
label: Acute leukemia
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002488 | Acute leukemia | Occasional (29-5%)"
explanation: Orphanet classifies acute leukemia as occasional.
- category: Disease Progression
name: Myelodysplasia
frequency: OCCASIONAL
description: >-
Myelodysplastic transformation may occur, particularly after prolonged
cytoreductive therapy.
phenotype_term:
preferred_term: Myelodysplasia
term:
id: HP:0002863
label: Myelodysplasia
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "HP:0002863 | Myelodysplasia | Occasional (29-5%)"
explanation: Orphanet classifies myelodysplasia as occasional.
biochemical:
- name: Complete Blood Count
notes: >-
Platelet count is elevated (>450,000/uL). Hemoglobin and WBC are typically
normal, helping distinguish ET from other myeloproliferative neoplasms.
- name: Bone Marrow Biopsy
notes: >-
Shows increased megakaryocytes that are large and mature with hyperlobated
nuclei without significant atypia or fibrosis. Helps exclude prefibrotic
myelofibrosis.
genetic:
- name: JAK2
association: Somatic Activating Mutations
notes: >-
JAK2 V617F occurs in approximately 55% of ET patients. Associated with
older age, higher hemoglobin, and increased thrombosis risk compared to
CALR-mutated ET.
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "JAK2 | Janus kinase 2 | hgnc:6192 | Disease-causing somatic mutation(s) in"
explanation: Orphanet lists JAK2 as a disease-causing somatic mutation gene for ET.
- name: CALR
association: Somatic Frameshift Mutations
notes: >-
CALR exon 9 frameshift mutations occur in approximately 25% of ET. Type 1
mutations more common. Associated with younger age, higher platelet count,
and lower thrombosis risk than JAK2 mutations.
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "CALR | calreticulin | hgnc:1455 | Disease-causing somatic mutation(s) in"
explanation: Orphanet lists CALR as a disease-causing somatic mutation gene for ET.
- name: MPL
association: Somatic Activating Mutations
notes: >-
MPL W515L/K mutations occur in approximately 3% of ET. Activates JAK-STAT
signaling through the thrombopoietin receptor.
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "MPL | MPL proto-oncogene, thrombopoietin receptor | hgnc:7217 | Disease-causing somatic mutation(s) in"
explanation: Orphanet lists MPL as a disease-causing somatic mutation gene for ET.
- name: SH2B3
association: Somatic Activating Mutations
notes: >-
SH2B3 (LNK) mutations are found in a subset of ET patients and contribute
to JAK-STAT pathway dysregulation.
evidence:
- reference: ORPHA:3318
supports: SUPPORT
snippet: "SH2B3 | SH2B adaptor protein 3 | hgnc:29605 | Disease-causing somatic mutation(s) in"
explanation: Orphanet lists SH2B3 as a disease-causing somatic mutation gene for ET.
treatments:
- name: Low-Dose Aspirin
description: >-
Recommended for all ET patients without contraindications. Reduces
microvascular symptoms (erythromelalgia, headache) and thrombotic events.
Use with caution if platelet count exceeds 1,000,000/uL due to acquired
von Willebrand disease risk.
treatment_term:
preferred_term: aspirin therapy
term:
id: MAXO:0000903
label: aspirin therapy
therapeutic_agent:
- preferred_term: acetylsalicylic acid
term:
id: CHEBI:15365
label: acetylsalicylic acid
- name: Hydroxyurea
description: >-
First-line cytoreductive therapy for high-risk ET patients (age >60 years
or prior thrombosis) and intermediate-risk patients with cardiovascular
risk factors. Well-tolerated and effective at reducing platelet count.
treatment_term:
preferred_term: chemotherapy
term:
id: MAXO:0000646
label: cancer chemotherapy
therapeutic_agent:
- preferred_term: hydroxyurea
term:
id: CHEBI:44423
label: hydroxyurea
- name: Anagrelide
description: >-
Selective platelet-lowering agent that inhibits megakaryocyte maturation.
Second-line option or used when hydroxyurea is contraindicated. May increase
arterial thrombosis and fibrotic transformation risk compared to hydroxyurea.
treatment_term:
preferred_term: targeted therapy
term:
id: NCIT:C93352
label: Targeted Therapy
therapeutic_agent:
- preferred_term: anagrelide
term:
id: CHEBI:142290
label: anagrelide
- name: Interferon-alpha
description: >-
Effective cytoreductive option particularly for younger patients, during
pregnancy, or when disease modification is desired. May reduce driver
mutation allele burden.
treatment_term:
preferred_term: immunotherapy
term:
id: NCIT:C15262
label: Immunotherapy
disease_term:
preferred_term: essential thrombocythemia
term:
id: MONDO:0005029
label: essential thrombocythemia
classifications:
icdo_morphology:
classification_value: Leukemia
harrisons_chapter:
- classification_value: cancer
- classification_value: hematologic malignancy
references:
- reference: DOI:10.1001/jama.2024.25349
title: Essential Thrombocythemia
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: ImportanceEssential thrombocythemia, a clonal myeloproliferative neoplasm with excessive platelet production, is associated with an increased risk of thrombosis and bleeding.
supporting_text: ImportanceEssential thrombocythemia, a clonal myeloproliferative neoplasm with excessive platelet production, is associated with an increased risk of thrombosis and bleeding.
evidence:
- reference: DOI:10.1001/jama.2024.25349
reference_title: Essential Thrombocythemia
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: ImportanceEssential thrombocythemia, a clonal myeloproliferative neoplasm with excessive platelet production, is associated with an increased risk of thrombosis and bleeding.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1002/9781119500537.ch82
title: Thrombocytosis and Essential Thrombocythemia
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Thrombocytosis and Essential Thrombocythemia
supporting_text: Thrombocytosis and Essential Thrombocythemia
- reference: DOI:10.1002/ajh.27216
title: 'Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management'
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: 'Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management'
supporting_text: OverviewEssential thrombocythemia is a Janus kinase 2 (JAK2) mutation‐prevalent myeloproliferative neoplasm characterized by clonal thrombocytosis; clinical course is often indolent but might be interrupted by thrombotic or hemorrhagic complications, microcirculatory symptoms (e.g., headaches, lightheadedness, and acral paresthesias), and, less frequently, by disease transformation into myelofibrosis (MF) or acute myeloid leukemia.DiagnosisIn addition to thrombocytosis (platelets ≥450 × 109/L), formal diagnosis requires the exclusion of other myeloid neoplasms, including prefibrotic MF, polycythemia vera, chronic myeloid leukemia, and myelodysplastic syndromes with ring sideroblasts and thrombocytosis.
evidence:
- reference: DOI:10.1002/ajh.27216
reference_title: 'Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: OverviewEssential thrombocythemia is a Janus kinase 2 (JAK2) mutation‐prevalent myeloproliferative neoplasm characterized by clonal thrombocytosis; clinical course is often indolent but might be interrupted by thrombotic or hemorrhagic complications, microcirculatory symptoms (e.g., headaches, lightheadedness, and acral paresthesias), and, less frequently, by disease transformation into myelofibrosis (MF) or acute myeloid leukemia.DiagnosisIn addition to thrombocytosis (platelets ≥450 × 109/L), formal diagnosis requires the exclusion of other myeloid neoplasms, including prefibrotic MF, polycythemia vera, chronic myeloid leukemia, and myelodysplastic syndromes with ring sideroblasts and thrombocytosis.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1038/s41408-023-00968-7
title: 'One thousand patients with essential thrombocythemia: the Florence-CRIMM experience'
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: 'One thousand patients with essential thrombocythemia: the Florence-CRIMM experience'
supporting_text: 'We describe 1000 patients with essential thrombocythemia seen at the Center Research and Innovation of Myeloproliferative Neoplasms (CRIMM), Florence, Italy, between 1980 and 2023: median age 59 years (18–95), females 65%, JAK2/CALR/MPL-mutated 66%/19%/4%, triple-negative (TN) 11%.'
evidence:
- reference: DOI:10.1038/s41408-023-00968-7
reference_title: 'One thousand patients with essential thrombocythemia: the Florence-CRIMM experience'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: 'We describe 1000 patients with essential thrombocythemia seen at the Center Research and Innovation of Myeloproliferative Neoplasms (CRIMM), Florence, Italy, between 1980 and 2023: median age 59 years (18–95), females 65%, JAK2/CALR/MPL-mutated 66%/19%/4%, triple-negative (TN) 11%.'
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1038/s41408-023-00972-x
title: 'One thousand patients with essential thrombocythemia: the Mayo Clinic experience'
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: 'One thousand patients with essential thrombocythemia: the Mayo Clinic experience'
supporting_text: 'We describe 1000 patients with essential thrombocythemia seen at the Mayo Clinic between 1967 and 2023: median age 58 years (18–90), females 63%, JAK2/CALR/MPL-mutated 62%/27%/3%, triple-negative (TN) 8%, extreme thrombocytosis (ExT; platelets ≥1000 × 109/L) 26%, leukocytosis (leukocyte count >11 × 109/L) 20%, and abnormal karyotype 6%.'
evidence:
- reference: DOI:10.1038/s41408-023-00972-x
reference_title: 'One thousand patients with essential thrombocythemia: the Mayo Clinic experience'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: 'We describe 1000 patients with essential thrombocythemia seen at the Mayo Clinic between 1967 and 2023: median age 58 years (18–90), females 63%, JAK2/CALR/MPL-mutated 62%/27%/3%, triple-negative (TN) 8%, extreme thrombocytosis (ExT; platelets ≥1000 × 109/L) 26%, leukocytosis (leukocyte count >11 × 109/L) 20%, and abnormal karyotype 6%.'
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1038/s41408-025-01235-7
title: Evolution of WHO diagnostic criteria in “Classical Myeloproliferative Neoplasms” compared with the International Consensus Classification
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Evolution of WHO diagnostic criteria in “Classical Myeloproliferative Neoplasms” compared with the International Consensus Classification
supporting_text: Evolution of WHO diagnostic criteria in “Classical Myeloproliferative Neoplasms” compared with the International Consensus Classification
- reference: DOI:10.1097/hs9.0000000000000056
title: Ruxolitinib for the Treatment of Essential Thrombocythemia
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Deregulated Janus Kinase 2 (JAK2) activation is central to the pathogenesis of most myeloproliferative neoplasms (MPNs), of which essential thrombocythemia (ET) is the most common entity.
supporting_text: Deregulated Janus Kinase 2 (JAK2) activation is central to the pathogenesis of most myeloproliferative neoplasms (MPNs), of which essential thrombocythemia (ET) is the most common entity.
evidence:
- reference: DOI:10.1097/hs9.0000000000000056
reference_title: Ruxolitinib for the Treatment of Essential Thrombocythemia
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Deregulated Janus Kinase 2 (JAK2) activation is central to the pathogenesis of most myeloproliferative neoplasms (MPNs), of which essential thrombocythemia (ET) is the most common entity.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1111/bjh.19403
title: 'Essential thrombocythaemia: A contemporary approach with new drugs on the horizon'
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia.
supporting_text: Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia.
evidence:
- reference: DOI:10.1111/bjh.19403
reference_title: 'Essential thrombocythaemia: A contemporary approach with new drugs on the horizon'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterized by an increased risk of vascular complications and a tendency to progress to myelofibrosis and acute leukaemia.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.1182/bloodadvances.2024013777
title: Risk of bleeding in patients with essential thrombocythemia and extreme thrombocytosis
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Approximately 25% of patients with essential thrombocythemia (ET) present with extreme thrombocytosis (ExT), defined as having a platelet count ≥1000 × 109/L.
supporting_text: Approximately 25% of patients with essential thrombocythemia (ET) present with extreme thrombocytosis (ExT), defined as having a platelet count ≥1000 × 109/L.
evidence:
- reference: DOI:10.1182/bloodadvances.2024013777
reference_title: Risk of bleeding in patients with essential thrombocythemia and extreme thrombocytosis
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Approximately 25% of patients with essential thrombocythemia (ET) present with extreme thrombocytosis (ExT), defined as having a platelet count ≥1000 × 109/L.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
- reference: DOI:10.59854/dhrrh.2024.2.3.125
title: 'Diagnosis and Management of Essential Thrombocythemia: A Comprehensive Review'
found_in:
- Essential_Thrombocythemia-deep-research-falcon.md
findings:
- statement: Myeloproliferative neoplasms, including essential thrombocythemia, are characterized by clonal proliferations of hematopoietic stem cells, leading to an increase in mature myeloid lineage cells.
supporting_text: Myeloproliferative neoplasms, including essential thrombocythemia, are characterized by clonal proliferations of hematopoietic stem cells, leading to an increase in mature myeloid lineage cells.
evidence:
- reference: DOI:10.59854/dhrrh.2024.2.3.125
reference_title: 'Diagnosis and Management of Essential Thrombocythemia: A Comprehensive Review'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Myeloproliferative neoplasms, including essential thrombocythemia, are characterized by clonal proliferations of hematopoietic stem cells, leading to an increase in mature myeloid lineage cells.
explanation: Deep research cited this publication as relevant literature for Essential Thrombocythemia.
ET is a clonal MPN with persistent thrombocytosis and bone marrow megakaryocytic proliferation, with clinical complications dominated by thrombosis, bleeding, and less frequently progression to myelofibrosis (MF) or acute myeloid leukemia (AML) (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2). - A contemporary definition from the AJH 2024 update describes: “Essential thrombocythemia is a Janus kinase 2 (JAK2) mutation‑prevalent myeloproliferative neoplasm characterized by clonal thrombocytosis” (tefferi2024essentialthrombocythemia2024 pages 1-2). - The JAMA review describes ET as a “clonal myeloproliferative neoplasm characterized by persistent thrombocytosis (platelet count ≥450 × 10^9/L) and increased risks of thrombosis and bleeding” (tefferi2025essentialthrombocythemia pages 1-2).
The retrieved evidence did not contain explicit ICD-10/ICD-11/MeSH/OMIM/Orphanet/MONDO codes; however, it consistently frames ET as a Philadelphia-negative/BCR-ABL1–negative MPN with diagnostic platelet threshold ≥450 ×10^9/L (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2).
| Identifier system | Identifier/code | Preferred name | Common synonyms/alternate names | Notes |
|---|---|---|---|---|
| MONDO | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Clonal myeloproliferative neoplasm characterized by persistent/clonal thrombocytosis; platelet threshold for diagnosis is ≥450 ×10^9/L in current criteria (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2, tefferi2024essentialthrombocythemia2024 pages 4-5) |
| ICD-10 | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Specific code not provided in retrieved evidence; disease described as a Philadelphia-negative myeloproliferative neoplasm with thrombotic/bleeding risk (ferrer‐marin2024essentialthrombocythaemiaa pages 1-2, tefferi2025essentialthrombocythemia pages 1-2) |
| ICD-11 | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Specific code not provided in retrieved evidence; diagnosis requires exclusion of other myeloid neoplasms including CML/BCR::ABL1-positive disease (thiele2025evolutionofwho pages 3-3, tefferi2024essentialthrombocythemia2024 pages 4-5) |
| MeSH | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Specific controlled-vocabulary identifier not retrieved; disease is BCR-ABL1-negative/Philadelphia-negative and marked by megakaryocytic proliferation with mature hyperlobulated megakaryocytes in loose clusters (allen2022thrombocytosisandessential pages 5-6, tefferi2024essentialthrombocythemia2024 pages 4-5) |
| OMIM | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Specific OMIM entry not captured; canonical driver mutations are JAK2, CALR, and MPL, supporting clonal disease definition (tefferi2024essentialthrombocythemia2024 pages 1-2, loscocco2024onethousandpatients pages 1-2) |
| Orphanet | Not captured in retrieved sources | Essential thrombocythemia | Essential thrombocythaemia; ET | Specific Orphanet identifier not captured; overview from recent reviews: chronic/clonal thrombocytosis, often indolent course, risk of thrombosis, hemorrhage, and less commonly progression to myelofibrosis or AML (ferrer‐marin2024essentialthrombocythaemiaa pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2) |
Table: This table summarizes the disease name, nomenclature, and identifier fields for Essential Thrombocythemia using only retrieved evidence. It is useful for knowledge-base curation because it separates supported definitional features from identifier systems whose exact codes were not captured in the current evidence set.
Most information in this report is derived from aggregated disease-level resources (large cohorts, systematic clinical reviews, and classification updates), including 1,000-patient institutional cohorts and guideline-style reviews (loscocco2024onethousandpatients pages 1-2, gangat2024onethousandpatients pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2).
ET is primarily caused by somatic (acquired) driver mutations in JAK2, CALR, or MPL, which upregulate JAK–STAT signaling and promote clonal megakaryopoiesis/platelet production (tefferi2024essentialthrombocythemia2024 pages 2-2, ferrer‐marin2024essentialthrombocythaemiaa pages 1-2). - ET driver mutations are typically mutually exclusive (JAK2 vs CALR vs MPL) and present in ~80–90% of patients depending on the cohort/definition (tefferi2024essentialthrombocythemia2024 pages 1-2, tefferi2025essentialthrombocythemia pages 1-2).
Host/clinical risk factors that increase thrombotic risk include: prior thrombosis, age >60 years, JAK2 mutation, and cardiovascular risk factors (e.g., hypertension) (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2). - In a Mayo 1,000-patient cohort (1967–2023), multivariable predictors of outcomes included hypertension (HR ~1.7 for overall survival; HR ~1.7 for arterial thrombosis-free survival) and JAK2 mutation (HR ~1.8 for arterial thrombosis-free survival) (gangat2024onethousandpatients pages 1-2).
Genetic risk/prognostic modifiers (co-mutations): additional somatic mutations are common and influence prognosis. - AJH 2024 update: ~50% have additional mutations (e.g., TET2, ASXL1, DNMT3A, SF3B1), and mutation associations include JAK2V617F with thrombosis and MPL/CALR-1 with increased MF transformation risk (tefferi2024essentialthrombocythemia2024 pages 1-2). - The 2024 BJH review notes that “triple-negative” ET may harbor other myeloid mutations including ASXL1, DNMT3A, TET2, EZH2, IDH1/2, RUNX1, SRSF2, SF3B1, TP53 (ferrer‐marin2024essentialthrombocythaemiaa pages 1-2).
No explicit protective genetic variants or environmental protective factors were captured in the retrieved evidence. However, both large-cohort analyses and expert updates suggest aspirin therapy is associated with reduced thrombosis risk in ET populations (a preventive/mitigating factor rather than primary prevention) (gangat2024onethousandpatients pages 1-2).
Direct gene–environment interaction evidence was not captured in the retrieved sources. Clinically, mutation status and cardiovascular risk factors interact in determining thrombotic risk and antiplatelet strategy (tefferi2025essentialthrombocythemia pages 1-2, ferrer‐marin2024essentialthrombocythaemiaa pages 4-5).
ET phenotypes span symptoms, signs, and lab/pathology abnormalities (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2).
A. Laboratory / hematologic - Persistent thrombocytosis (platelets ≥450 ×10^9/L) (diagnostic threshold) (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 4-5). - Suggested HPO: Thrombocytosis (HP:0001894).
B. Thrombotic manifestations - Increased risk of arterial thrombosis and venous thrombosis (tefferi2025essentialthrombocythemia pages 1-2). - JAMA review: increased risk of arterial thrombosis 11% and venous thrombosis 7% (tefferi2025essentialthrombocythemia pages 1-2). - Suggested HPO: Thrombosis (HP:0001977); Arterial thrombosis (HP:0031048); Venous thrombosis (HP:0004936).
C. Bleeding manifestations - Hemorrhagic complications reported (JAMA review: 8%) (tefferi2025essentialthrombocythemia pages 1-2). - Bleeding risk can be associated with acquired von Willebrand factor abnormalities, especially with extreme thrombocytosis (venkat2024riskofbleeding pages 3-4, tefferi2024essentialthrombocythemia2024 pages 11-11). - Suggested HPO: Abnormal bleeding (HP:0001892).
D. Microcirculatory symptoms - Microcirculatory symptoms such as “headaches, lightheadedness, and acral paresthesias” are noted (tefferi2024essentialthrombocythemia2024 pages 1-2). - Suggested HPO: Headache (HP:0002315); Lightheadedness (HP:0030931); Paresthesia (HP:0003401).
E. Disease evolution - Progression to myelofibrosis and AML occurs in a minority (tefferi2025essentialthrombocythemia pages 1-2, tefferi2024essentialthrombocythemia2024 pages 1-2). - Suggested HPO: Myelofibrosis (HP:0005532); Acute myeloid leukemia (HP:0004808).
Formal QoL instrument results were not captured directly, but symptom burden is a recurring treatment target; ruxolitinib is noted to be superior mainly for symptom control in hydroxyurea-resistant/intolerant ET in MAJIC-ET-related summaries (gunawan2018ruxolitinibforthe pages 1-2, ferrer‐marin2024essentialthrombocythaemiaa pages 7-8).
Large 2024 real-world cohorts provide high-confidence mutation frequency estimates: - Mayo cohort (n=1000): JAK2/CALR/MPL 62%/27%/3%, triple-negative 8% (gangat2024onethousandpatients pages 1-2). - Florence-CRIMM cohort (n=1000): JAK2/CALR/MPL 66%/19%/4%, triple-negative 11% (loscocco2024onethousandpatients pages 1-2). - JAMA review: approximately 90% have JAK–STAT-activating variants: JAK2 64%, CALR 23%, MPL 4% (tefferi2025essentialthrombocythemia pages 1-2).
| Metric | Value | Population/Study | Year | Notes | Source (citation id) |
|---|---|---|---|---|---|
| Annual incidence | 1.5 per 100,000 persons | US population; JAMA review | 2025 | Explicitly stated as annual incidence in the US | (tefferi2025essentialthrombocythemia pages 1-2) |
| Annual incidence | 0.6–2.5 per 100,000/year | General population; contemporary review | 2024 | Review estimate for ET incidence | (ferrer‐marin2024essentialthrombocythaemiaa pages 1-2) |
| Incidence | 1–5 per 100,000 | Review article population estimate | 2024 | Reported as incidence; unit phrasing in source not explicitly annual | (lazar2024diagnosisandmanagement pages 1-3) |
| Prevalence | 38–57 per 100,000 | Review article population estimate | 2024 | Reported prevalence range | (lazar2024diagnosisandmanagement pages 1-3) |
| Median age at diagnosis | 59 years | General ET population; JAMA review | 2025 | Median age at diagnosis | (tefferi2025essentialthrombocythemia pages 1-2) |
| Median age | 58 years | Mayo Clinic ET cohort (n=1000) | 2024 | Range 18–90 years | (gangat2024onethousandpatients pages 1-2) |
| Female sex | 63% | Mayo Clinic ET cohort (n=1000) | 2024 | Cohort sex distribution | (gangat2024onethousandpatients pages 1-2) |
| Median age | 59 years | Florence-CRIMM ET cohort (n=1000) | 2024 | Range 18–95 years | (loscocco2024onethousandpatients pages 1-2) |
| Female sex | 65% | Florence-CRIMM ET cohort (n=1000) | 2024 | Cohort sex distribution | (loscocco2024onethousandpatients pages 1-2) |
| JAK2 mutation frequency | 62% | Mayo Clinic ET cohort (n=1000) | 2024 | Driver mutation distribution | (gangat2024onethousandpatients pages 1-2) |
| CALR mutation frequency | 27% | Mayo Clinic ET cohort (n=1000) | 2024 | Driver mutation distribution | (gangat2024onethousandpatients pages 1-2) |
| MPL mutation frequency | 3% | Mayo Clinic ET cohort (n=1000) | 2024 | Driver mutation distribution | (gangat2024onethousandpatients pages 1-2) |
| Triple-negative frequency | 8% | Mayo Clinic ET cohort (n=1000) | 2024 | Driver mutation distribution | (gangat2024onethousandpatients pages 1-2) |
| JAK2 mutation frequency | 66% | Florence-CRIMM ET cohort (n=1000) | 2024 | Driver mutation distribution | (loscocco2024onethousandpatients pages 1-2) |
| CALR mutation frequency | 19% | Florence-CRIMM ET cohort (n=1000) | 2024 | Driver mutation distribution | (loscocco2024onethousandpatients pages 1-2) |
| MPL mutation frequency | 4% | Florence-CRIMM ET cohort (n=1000) | 2024 | Driver mutation distribution | (loscocco2024onethousandpatients pages 1-2) |
| Triple-negative frequency | 11% | Florence-CRIMM ET cohort (n=1000) | 2024 | Driver mutation distribution | (loscocco2024onethousandpatients pages 1-2) |
| JAK2 mutation frequency | 64% | General ET population; JAMA review | 2025 | Approximately 90% of patients had JAK-STAT-activating variants overall | (tefferi2025essentialthrombocythemia pages 1-2) |
| CALR mutation frequency | 23% | General ET population; JAMA review | 2025 | Approximately 90% of patients had JAK-STAT-activating variants overall | (tefferi2025essentialthrombocythemia pages 1-2) |
| MPL mutation frequency | 4% | General ET population; JAMA review | 2025 | Approximately 90% of patients had JAK-STAT-activating variants overall | (tefferi2025essentialthrombocythemia pages 1-2) |
| Triple-negative frequency | ~10% | General ET population; JAMA review | 2025 | Inferred from “approximately 90%” having JAK2/CALR/MPL variants | (tefferi2025essentialthrombocythemia pages 1-2) |
| Arterial thrombosis risk | 11% | General ET population; JAMA review | 2025 | Reported increased risk in ET | (tefferi2025essentialthrombocythemia pages 1-2) |
| Venous thrombosis risk | 7% | General ET population; JAMA review | 2025 | Reported increased risk in ET | (tefferi2025essentialthrombocythemia pages 1-2) |
| Hemorrhagic complication risk | 8% | General ET population; JAMA review | 2025 | Reported increased risk in ET | (tefferi2025essentialthrombocythemia pages 1-2) |
| Arterial thrombosis after diagnosis | 9% | Cohort cited in JAMA review | 2025 | Reported alongside 6% venous thrombosis after diagnosis | (tefferi2025essentialthrombocythemia pages 3-4) |
| Venous thrombosis after diagnosis | 6% | Cohort cited in JAMA review | 2025 | Reported alongside 9% arterial thrombosis after diagnosis | (tefferi2025essentialthrombocythemia pages 3-4) |
| Hemorrhagic events | 7.3% | Review article population estimate | 2024 | Predominantly cutaneous/mucosal or gastrointestinal | (lazar2024diagnosisandmanagement pages 1-3) |
| Myelofibrosis transformation | ~10% | General ET population; JAMA review | 2025 | At median 8.5 years from diagnosis | (tefferi2025essentialthrombocythemia pages 1-2) |
| Acute myeloid leukemia transformation | ~3% | General ET population; JAMA review | 2025 | At median 8.5 years from diagnosis | (tefferi2025essentialthrombocythemia pages 1-2) |
| Myelofibrosis transformation | 4%–11% | Long-term review estimate | 2024 | At 15 years | (lazar2024diagnosisandmanagement pages 1-3) |
| AML transformation | 2%–5% | Long-term review estimate | 2024 | Long-term progression estimate | (lazar2024diagnosisandmanagement pages 1-3) |
| Leukemic transformation | <1% | General ET population; AJH update | 2024 | At 10 years; higher in select JAK2-mutated or karyotype-abnormal cases | (tefferi2024essentialthrombocythemia2024 pages 1-2) |
| Median overall survival | ~18 years | General ET population; AJH update | 2024 | Review estimate | (tefferi2024essentialthrombocythemia2024 pages 1-2) |
| Median overall survival | >35 years | Patients diagnosed at age ≤40 years; JAMA review | 2025 | Survival exceeds 35 years in younger patients | (tefferi2025essentialthrombocythemia pages 1-2) |
| Median survival range | 10 years to not reached | Mayo Clinic ET cohort risk models | 2024 | HR-based risk models | (gangat2024onethousandpatients pages 1-2) |
| 20-year leukemia incidence | 3% to 12.8% | Mayo Clinic ET cohort risk models | 2024 | Across model-defined risk groups | (gangat2024onethousandpatients pages 1-2) |
| 20-year myelofibrosis incidence | 21% to 49% | Mayo Clinic ET cohort risk models | 2024 | Across model-defined risk groups | (gangat2024onethousandpatients pages 1-2) |
Table: This table compiles key quantitative epidemiology, mutation frequency, thrombosis/bleeding risk, transformation, and survival data for essential thrombocythemia from the retrieved evidence. It is useful for quickly comparing population-level estimates with large real-world Mayo and Florence 1000-patient cohorts.
No specific environmental toxins, lifestyle exposures, or infectious triggers were captured as causal contributors in the retrieved ET-focused evidence. ET risk/complications are clinically influenced by cardiovascular risk factors (e.g., hypertension, diabetes), but these are generally modeled as modifiers of thrombotic risk rather than etiologic exposures (tefferi2025essentialthrombocythemia pages 1-2, gangat2024onethousandpatients pages 1-2).
ET is principally a somatic clonal hematopoietic disease driven by acquired mutations in hematopoietic stem/progenitor cells; a Mendelian inheritance pattern was not supported by the retrieved evidence (tefferi2024essentialthrombocythemia2024 pages 2-2, tefferi2024essentialthrombocythemia2024 pages 1-2).
The AJH 2024 update reproduces the ICC framework: diagnosis requires “meeting all four major criteria or meeting the first three major criteria plus one minor criterion” (tefferi2024essentialthrombocythemia2024 pages 4-5). Major criteria elements include: 1. Platelets ≥450 ×10^9/L (tefferi2024essentialthrombocythemia2024 pages 4-5). 2. Bone marrow: megakaryocyte proliferation with mature cytology/hyperlobulated nuclei, loose clustering, and absent or ≤ grade 1 fibrosis (tefferi2024essentialthrombocythemia2024 pages 4-5). 3. Exclusion of other myeloid neoplasms (including PV, prefibrotic MF, CML) (tefferi2024essentialthrombocythemia2024 pages 4-5). 4. Presence of driver mutation JAK2/CALR/MPL (tefferi2024essentialthrombocythemia2024 pages 4-5).
Bone marrow morphology emphasized in practice includes normocellularity for age, increased mature megakaryocytes in loose clusters, and reticulin fibrosis < grade 1 (loscocco2024onethousandpatients pages 1-2).
Differential diagnoses include other MPNs and reactive thrombocytosis: - JAMA review lists PV, primary myelofibrosis, CML, inflammatory conditions, infections, splenectomy, iron deficiency anemia, and solid tumors among differentials (tefferi2025essentialthrombocythemia pages 1-2).
WHO/ICC-aligned approaches emphasize driver mutation testing for JAK2/CALR/MPL (thiele2025evolutionofwho pages 3-4, tefferi2024essentialthrombocythemia2024 pages 4-5).
The AJH 2024 update frames ET therapy around thrombosis prevention, using risk groups incorporating thrombosis history, age, and JAK2 status (tefferi2024essentialthrombocythemia2024 pages 1-2).
Figure-based algorithm (visual evidence) - The AJH 2024 update provides a treatment algorithm stratifying “very low / low / intermediate / high” risk and selecting observation vs aspirin vs cytoreduction (tefferi2024essentialthrombocythemia2024 media 9b23e152).
MAXO suggestion: antiplatelet therapy.
MAXO suggestions: cytoreductive therapy; interferon therapy.
A key 2024 development is more granular evidence on bleeding in ET with extreme thrombocytosis (ExT). - Venkat et al. (Blood Adv. Dec 2024) concludes: “There is no clear indication for cytoreduction to decrease bleeding risk based on a platelet threshold of 1 million alone” (abstract key points) (venkat2024riskofbleeding pages 1-2). - The same study reports ExT is associated with lower vWF antigen/activity, consistent with acquired vWF abnormalities (venkat2024riskofbleeding pages 3-4). - AJH 2024 emphasizes that platelet extremes alone do not necessarily increase thrombosis/hemorrhage risk, and that therapy modification is mainly warranted when ExT is accompanied by AvWS (tefferi2024essentialthrombocythemia2024 pages 11-12).
Ruxolitinib (JAK1/2 inhibitor; selected settings) - 2024 BJH review summarizes that in hydroxyurea-resistant/intolerant ET, ruxolitinib improved some symptoms but did not reduce thrombosis/bleeding/transformation and did not show superiority over best available therapy (MAJIC-ET) (ferrer‐marin2024essentialthrombocythaemiaa pages 7-8). - Earlier ET-specific review similarly notes superiority mainly in symptom control vs conventional therapy (gunawan2018ruxolitinibforthe pages 1-2).
Bomedemstat (LSD1 inhibitor; emerging therapy) - AJH 2024 update: bomedemstat is “an orally active LSD1 inhibitor” and in a phase 2 study (NCT04254978) achieved platelet response (≤400×10^9/L) in 94% with median time to response 8 weeks; common AEs included dysgeusia (43%), constipation (27%), fatigue (23%), thrombocytopenia (23%), and discontinuation ~20% (tefferi2024essentialthrombocythemia2024 pages 17-17). - Phase 3 registry trial: NCT06079879 compares bomedemstat vs best available therapy in HU inadequate response/intolerant ET; start date 2023‑12‑31; planned enrollment 340; primary endpoint durable clinicohematologic response by week 52 (NCT06079879 chunk 1).
Ropeginterferon alfa-2b (phase 3 trial in ET) - SURPASS-ET registry trial: NCT04285086 is an open-label, randomized, phase 3 study comparing ropeginterferon alfa‑2b vs anagrelide in HU-resistant/intolerant ET; enrollment 174; primary outcomes include blood count remission, symptom improvement, and absence of thrombotic/hemorrhagic events (NCT04285086 chunk 1).
MAXO suggestions: interferon therapy; JAK inhibitor therapy; histone demethylase inhibitor therapy.
No primary-prevention interventions were captured (ET is primarily somatic clonal disease). Secondary/tertiary prevention focuses on prevention of thrombosis/bleeding complications via risk-adapted antiplatelet therapy and cytoreduction (tefferi2024essentialthrombocythemia2024 pages 1-2, ferrer‐marin2024essentialthrombocythaemiaa pages 3-4).
No naturally occurring animal disease evidence for ET was captured in the retrieved sources for this report.
While mechanistic statements reference preclinical support for mutant CALR/MPL biology, specific model organism systems and phenotypes were not captured in the retrieved evidence excerpts (tefferi2024essentialthrombocythemia2024 pages 2-2).
References
(loscocco2024onethousandpatients pages 1-2): Giuseppe G. Loscocco, Francesca Gesullo, Giulio Capecchi, Alessandro Atanasio, Chiara Maccari, Francesco Mannelli, Alessandro M. Vannucchi, and Paola Guglielmelli. One thousand patients with essential thrombocythemia: the florence-crimm experience. Blood Cancer Journal, Jan 2024. URL: https://doi.org/10.1038/s41408-023-00968-7, doi:10.1038/s41408-023-00968-7. This article has 43 citations and is from a domain leading peer-reviewed journal.
(ferrer‐marin2024essentialthrombocythaemiaa pages 1-2): Francisca Ferrer‐Marín, Juan Carlos Hernández‐Boluda, and Alberto Alvarez‐Larrán. Essential thrombocythaemia: a contemporary approach with new drugs on the horizon. British Journal of Haematology, 204:1605-1616, Apr 2024. URL: https://doi.org/10.1111/bjh.19403, doi:10.1111/bjh.19403. This article has 7 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 pages 1-2): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(tefferi2025essentialthrombocythemia pages 1-2): Ayalew Tefferi, Naseema Gangat, Giuseppe Gaetano Loscocco, Paola Guglielmelli, Natasha Szuber, Animesh Pardanani, Attilio Orazi, Tiziano Barbui, and Alessandro Maria Vannucchi. Essential thrombocythemia. JAMA, 333:701, Feb 2025. URL: https://doi.org/10.1001/jama.2024.25349, doi:10.1001/jama.2024.25349. This article has 22 citations.
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(tefferi2024essentialthrombocythemia2024 pages 4-5): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(thiele2025evolutionofwho pages 3-3): Jürgen Thiele, Hans Michael Kvasnicka, Umberto Gianelli, Daniel A. Arber, Ayalew Tefferi, Alessandro M. Vannucchi, Tiziano Barbui, and Attilio Orazi. Evolution of who diagnostic criteria in “classical myeloproliferative neoplasms” compared with the international consensus classification. Blood Cancer Journal, Mar 2025. URL: https://doi.org/10.1038/s41408-025-01235-7, doi:10.1038/s41408-025-01235-7. This article has 9 citations and is from a domain leading peer-reviewed journal.
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(tefferi2025essentialthrombocythemia pages 3-4): Ayalew Tefferi, Naseema Gangat, Giuseppe Gaetano Loscocco, Paola Guglielmelli, Natasha Szuber, Animesh Pardanani, Attilio Orazi, Tiziano Barbui, and Alessandro Maria Vannucchi. Essential thrombocythemia. JAMA, 333:701, Feb 2025. URL: https://doi.org/10.1001/jama.2024.25349, doi:10.1001/jama.2024.25349. This article has 22 citations.
(thiele2025evolutionofwho pages 3-4): Jürgen Thiele, Hans Michael Kvasnicka, Umberto Gianelli, Daniel A. Arber, Ayalew Tefferi, Alessandro M. Vannucchi, Tiziano Barbui, and Attilio Orazi. Evolution of who diagnostic criteria in “classical myeloproliferative neoplasms” compared with the international consensus classification. Blood Cancer Journal, Mar 2025. URL: https://doi.org/10.1038/s41408-025-01235-7, doi:10.1038/s41408-025-01235-7. This article has 9 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 media 9b23e152): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 pages 10-11): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 pages 11-12): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 pages 12-13): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(tefferi2024essentialthrombocythemia2024 pages 17-17): Ayalew Tefferi, Alessandro Maria Vannucchi, and Tiziano Barbui. Essential thrombocythemia: 2024 update on diagnosis, risk stratification, and management. American Journal of Hematology, 99:697-718, Jan 2024. URL: https://doi.org/10.1002/ajh.27216, doi:10.1002/ajh.27216. This article has 141 citations and is from a domain leading peer-reviewed journal.
(NCT06079879 chunk 1): A Study of Bomedemstat (IMG-7289/MK-3543) Compared to Best Available Therapy (BAT) in Participants With Essential Thrombocythemia and an Inadequate Response or Intolerance of Hydroxyurea (MK-3543-006). Merck Sharp & Dohme LLC. 2023. ClinicalTrials.gov Identifier: NCT06079879
(NCT04285086 chunk 1): Ropeginterferon Alfa-2b (P1101) vs. Anagrelide in Essential Thrombocythemia Patients With Hydroxyurea Resistance or Intolerance. PharmaEssentia. 2020. ClinicalTrials.gov Identifier: NCT04285086
(ferrer‐marin2024essentialthrombocythaemiaa pages 3-4): Francisca Ferrer‐Marín, Juan Carlos Hernández‐Boluda, and Alberto Alvarez‐Larrán. Essential thrombocythaemia: a contemporary approach with new drugs on the horizon. British Journal of Haematology, 204:1605-1616, Apr 2024. URL: https://doi.org/10.1111/bjh.19403, doi:10.1111/bjh.19403. This article has 7 citations and is from a domain leading peer-reviewed journal.