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Essential thrombocytosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2] Parth Vikram Singh, MBBS[3]

Synonyms and keywords: Essential thrombocythemia, primary thrombocythemia, congenital essential thrombocytosis, congenital essential thrombocythaemia, hereditary essential thrombocytosis, familial essential thrombocytosis, Epstein-Goedel syndrome, Hemorrhagic thrombocytosis, ET

Overview

Overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]Parth Vikram Singh, MBBS[3]

Overview

Essential thrombocytosis (ET) or primary thrombocytosis is a clonal myeloproliferative neoplasm characterized by thrombocytosis and risks of thrombosis and bleeding. It is a rare hematologic disorder which arises from hematopoietic stem cells that give rise to megakaryocytes which in turn produce platelets (thrombocytes), that are normally involved in blood clotting. Essential thrombocytosis is characterized by overproduction of platelets in the absence of an underlying disease. ET is defined by a persistent platelet count >=450 x 10^9/L.[1] Essential thrombocytosis was first defined by Emil Epstein and Alfred Goedel, two Austrian pathologists, in the year 1934 and was initially called hemorrhagic thrombocythemia.[2] Subsequently, essential thrombocytosis was classified as a myeloproliferative disorder along with chronic myelogenous leukemia (CML), polycythemia vera (PV), and chronic idiopathic myelofibrosis (CIMF).[3] Approximately 90% of patients have JAK-STAT pathway driver variants (JAK2 64%, CALR 23%, MPL 4%); about 10% are triple-negative. The incidence of essential thrombocytosis is approximately 0.6-2.5 cases per 100,000 individuals worldwide annually.[4] The annual incidence rate in the US is 1.5 per 100,000 persons. A Swedish population-based study with an age-standardized incidence 1.6 per 100,000, similar to US adults. The prevalence of essential thrombocytosis is about 30 for every 100,000 people worldwide.[5] Females are more commonly affected with essential thrombocytosis than males.[6] The female to male ratio is approximately 2 to 1.[4] The median age at diagnosis is 59 years, and the median overall survival exceeds 35 years among those diagnosed at age 40 years or younger. Symptoms of essential thrombocytosis include vision disturbances, transient loss of consciousness, chest pain, intense burning pain in hands or feet (erythromelalgia), numbness and tingling of hands and feet, persistent and painful erection of the penis (priapism).[7] Bone marrow biopsy may be helpful in the diagnosis of essential thrombocytosis, in addition to ruling out other secondary causes of thrombocytosis.[8] The majority of cases of essential thrombocytosis only require supportive care. ET is associated with increased risks of arterial thrombosis (11%), venous thrombosis (7%), and hemorrhagic complications (8%). Pharmacologic medical therapies for essential thrombocytosis include aspirin therapy for low risk patients and platelet lowering drugs such as (hydroxyurea, interferon-α, and anagrelide) for high risk patients.

Historical Perspective

Essential thrombocytosis was first defined by Emil Epstein and Alfred Goedel, two Austrian pathologists, in the year 1934 and was initially called hemorrhagic thrombocythemia.[2]

Classification

There is no classification system established for essential thrombocytosis. However, essential thrombocytosis may be broadly classified into sporadic and familial forms.[9]

Pathophysiology

Essential thrombocytosis arises from hematopoietic stem cells which give rise to megakaryocytes which give rise to platelets (thrombocytes), that are normally involved in blood clotting. Approximately 90% of patients have JAK-STAT pathway driver variants: JAK2 (64%), CALR (23%), and MPL (4%). About 10% are triple-negative (no JAK2/CALR/MPL variant). Development of essential thrombocytosis is the result of a genetic mutation in the janus kinase 2 (JAK2) gene in 50% of the patients. Other genes that may be involved in the pathogenesis of essential thrombocytosis are CALR, MPL, and THPO genes.[10] On microscopic histopathological analysis, thrombocytosis and bone marrow hyperplasia with hyperlobated megakaryotic nuclei evident of thrombopoiesis are characteristic findings of essential thrombocytosis.

Epidemiology and Demographics

The incidence of essential thrombocytosis is approximately 0.6-2.5 cases per 100,000 individuals worldwide annually.[4] The annual incidence rate of ET in the US is 1.5 per 100,000 persons (age-standardized incidence 1.6 per 100,000 in a Swedish population-based study). The median age at diagnosis is 59 years.[11] The prevalence of essential thrombocytosis is approximately 30 per 100,000 individuals worldwide.[5] The incidence of essential thrombocytosis increases with age; the median age at diagnosis is 65-70 years. Patients of all age groups may develop essential thrombocytosis. However, essential thrombocytosis commonly affects individuals older than 60 years of age.[6] Females are more commonly affected with essential thrombocytosis than males.[6] The female to male ratio is approximately 2 to 1.[4]

Risk Factors

Common risk factor in the development of essential thrombocytosis is female sex.[12] Common risk factors in the development of thrombotic complications in patients with essential thrombocytosis are previous history of thrombotic events and age greater than 60 years.[12]

Screening

Screening for essential thrombocytosis by cell-based quantitative assays for JAK2V617F mutation is recommended among individuals with a positive family history for the disease (autosomal dominant inheritance) and in patients who present with thrombocytosis, erythrocytosis, and monocytosis.[13][14]

Causes

Essential thrombocytosis may be caused by a mutation in the janus kinase 2 (JAK2) gene (in 64% of the patients), CALR (23%), MPL (4%), or THPO genes. About 10% are triple-negative (no JAK2/CALR/MPL variant).

Differential Diagnosis

Essential thrombocytosis must be differentiated from other causes of thrombocytosis, such as chronic myelogenous leukemia (CML), myelodysplastic syndrome, polycythemia vera, primary myelofibrosis, secondary thrombocytosis.[15] Secondary causes account for >85% of thrombocytosis; exclude secondary thrombocytosis before diagnosing ET.

Table: ET vs secondary thrombocytosis[16]

Feature Suggests ET Suggests secondary thrombocytosis
Clinical clues Microcirculatory symptoms like s include erythromelalgia, acral paresthesias, burning toes and fingers, blurred vision, or headaches (~29%);

thrombosis history (~22%);

splenomegaly (~12%);

splanchnic vein thrombosis (~5%);

Superficial thrombophlebitis (<5%);

cerebral vein thrombosis (<2%)

Symptoms/signs of infection/inflammation/malignancy;

recent trauma/surgery;

prior splenectomy;

iron deficiency

Exam Palpable splenomegaly Absence of splenomegaly
Labs Sustained thrombocytosis; JAK2/CALR/MPL variant detected New-onset thrombocytosis;

positive blood culture;

neutrophilia/left shift;

elevated CRP/ESR;

iron deficiency;

functional asplenia markers (Howell-Jolly bodies, nucleated RBCs)

Treatment note – No evidence supports routine aspirin/anticoagulation/cytoreduction/plateletpheresis for reactive thrombocytosis regardless of platelet count

Table: Common causes of secondary thrombocytosis.[17]

Cause (percent representation) Mechanism Typical management
Infections (17%-43%) Inflammatory cytokines; nonspecific stimulation; platelet release Resolves with treatment; may persist with chronic infection
Inflammatory diseases (4%-12%) Increased thrombopoietic factors Treat underlying condition
Malignancy (10%) (eg, lung/GI/lymphomas) Increased thrombopoietic factors Treat underlying malignancy
Iron deficiency (7%-11%) Increased progenitor proliferation Replete iron; typically resolves in 1-2 months
Splenectomy (1%-2%) Decreased sequestration/turnover; peak 1-3 weeks May be lifelong; may resolve in 1-5 years
Surgery/trauma (22%-32%) Increased thrombopoietic factors from tissue damage Resolves in days to weeks
Rebound thrombocytosis (7%) Recovery from chemotherapy; cessation of excess alcohol; vitamin deficiency/ITP treatment Resolves in 2-4 weeks
Drugs (1%-3%) Medication-related Dose modify/stop (variable)

Natural History, Complications and Prognosis

If left untreated, patients with essential thrombocytosis may progress to develop symptoms like headache, dizziness, vision disturbances, chest pain, intense burning pain in hands and/or feet (erythromelalgia), numbness and tingling of hands and feet, priapism (persistent and painful erection of the penis) and so on depending on the vessel occluded with the thrombus.

Common complications of essential thrombocytosis include thrombotic events (DVT, cerebrovascular accidents,etc), bleeding (bruises, gum bleeds, epistaxis, etc), acute leukemia and myelofibrosis.[18][19] ET is associated with increased risks of arterial thrombosis (11%), venous thrombosis (7%), and hemorrhagic complications (8%).[20] In one study of 170 patients with ET, 20% had laboratory findings consistent with acquired von Willebrand syndrome (AvWS); mean platelet count was 701 x 10^9/L with AvWS vs 472 x 10^9/L without AvWS (P < .01). Screening for clinically relevant AvWS is generally advised when platelet count is >1000 x 10^9/L (reported in 16%–26%) because this is associated with increased bleeding susceptibility. Aspirin is generally avoided if von Willebrand factor activity is <20%-30% until corrected with cytoreductive therapy.

Prognosis is generally good, and the survival rate of patients is usually normal with regular medical supervision. However, the disease may rarely undergo a leukemic conversion or develop myelofibrosis. At a median of 8.5 years from diagnosis, approximately 10% of patients develop myelofibrosis and about 3% develop acute myeloid leukemia.

Median overall survival varies by age and sex:

  • <50 years: 39 years (women) and 31 years (men);
  • 50-70 years: 21 years (women) and 20 years (men);
  • >70 years: 11.2 years (women) and 8.4 years (men).

Diagnosis

The diagnosis of ET should not be made until secondary causes of thrombocytosis are excluded, because secondary causes account for more than 85% of thrombocytosis cases. Patients with thrombocytosis should be evaluated for infections, solid tumor malignancy (eg, breast or lung carcinomas; lymphomas) or lymphoma, postsplenectomy state/functional asplenia (eg, Howell-Jolly bodies), iron deficiency, and rebound thrombocytosis (eg, recovery from excess alcohol use or chemotherapy). If no secondary cause is suggested clinically, peripheral blood testing for JAK2, CALR, and MPL variants is recommended.

Diagnostic Criteria

The diagnosis of essential thrombocytosis is made when all four of the following diagnostic criteria are met:[8]

  • Sustained elevation of platelet counts > 450,000,000 × 10³/L, AND
  • Bone marrow biopsy specimen showing proliferation, mainly of the megakaryocytic lineage with increased numbers of enlarged, mature megakaryocytes and no significant increase or left-shift of neutrophil granulopoiesis or erythropoiesis, AND
  • Not meeting WHO criteria for polycythemia vera (PV), PMF, CML, MDS, or other myeloid neoplasm, AND
  • Demonstration of JAK2 617VF or other clonal marker, or in the absence of a clonal marker, no evidence for reactive thrombocytosis. Presence of the first 3 criteria plus no evidence for secondary thrombocytosis is also sufficient for diagnosis.

History and Symptoms

People with essential thrombocytosis are usually asymptomatic. Symptoms[7] of essential thrombocytosis include vision disturbances, transient loss of consciousness, chest pain, intense burning pain in hands or feet (erythromelalgia), numbness and tingling of hands and feet, persistent and painful erection of the penis (priapism). Neurologic symptoms like headache may occur but the pathophysiology is not completely understood.[7] A positive family history of may be present in those with familial essential thrombocytosis.

Laboratory Findings

Laboratory findings consistent with the diagnosis of essential thrombocytosis include abnormal complete blood count (CBC), elevated platelet count, peripheral blood smear showing large platelets, megakaryocyte fragments and platelet aggregates, presence of JAK2 mutation and absence of BCR-ABL or Philadelphia chromosome.[21] Leukocytosis, erythrocytosis, and mild anemia may be present. Bone marrow biopsy is an important test and needed to make a diagnosis of essential thrombocytosis as per WHO definition.[8]

Electrocardiogram

There are no EKG findings associated with essential thrombocytosis. However, EKG should always be ordered in essential thrombocytosis patients who present with chest pain to rule out other dangerous causes of chest pain like myocardial infarction (MI).

Chest X Ray

A chest x-ray is not diagnostic of essential thrombocytosis. However, a chest x-ray may be a helpful test in the management of complications that develop due to essential thrombocytosis, such as pulmonary thromboembolism.[22]

CT Scan

CT scan is not diagnostic of essential thrombocytosis. Findings on abdominal CT suggestive of essential thrombocytosis include splenomegaly. A spiral chest CT may be helpful in the diagnosis of complications from essential thrombocytosis like pulmonary thromboembolism in patients with suggestive symptoms.[22]

MRI

There are no MRI findings associated with essential thrombocytosis.

Ultrasound

Abdominal ultrasound may be helpful in the diagnosis of Essential thrombocytosis. Findings on abdominal ultrasound suggestive of essential thrombocytosis include Splenomegaly.[23] There are no electrocardiogram findings associated with essential thrombocytosis.

Other Imaging Findings

There are no other imaging studies associated with essential thrombocytosis.

Bone Marrow Biopsy Findings

Bone marrow biopsy is an important test and needed to make a diagnosis of essential thrombocytosis[8] as per WHO definition. The bone marrow biopsy shows hypercellularity with clusters of megakaryocytes that stain positive for iron. There may be increased reticulin but no collagen fibrosis.

Treatment

Medical Therapy

The majority of cases of essential thrombocytosis only require supportive care. Pharmacologic medical therapies for essential thrombocytosis include aspirin therapy for patients at low risk and platelet lowering drugs (Hydroxyurea, interferon-α and anagrelide) for patients at high risk for thrombosis.

Treatment Algorithm and Evidence[24]

1) Assess JAK2 status and prior major thrombosis (excluding superficial thrombophlebitis).

2) Very low risk (age <60, JAK2 wild type, no prior thrombosis): observation alone or once-daily aspirin; if cardiovascular risk factors (eg. hypertension, diabetes mellitus, hyperlipidemia, tobacco use) are present, use once-daily aspirin.

3) Low risk (age <60, JAK2 variant, no prior thrombosis): twice-daily aspirin (consider once-daily in selected cases per clinician judgment).

4) Intermediate risk (age >=60, JAK2 wild type, no prior thrombosis): twice-daily aspirin; in selected patients if cardiovascular risk factors are present, consider hydroxyurea and once-daily aspirin.

5) High risk (prior thrombosis OR age >=60 with JAK2 variant): hydroxyurea plus aspirin (often twice-daily); if venous thrombosis, add systemic anticoagulation.

6) Second-line cytoreductive options for hydroxyurea intolerance/refractory disease: pegylated interferon alfa or busulfan.

Aspirin safety note: In extreme thrombocytosis, aspirin requires monitoring for bleeding and acquired von Willebrand syndrome; aspirin is generally avoided if von Willebrand factor activity is <20%-30%. Screening is advised for platelet count >1000 x 10^9/L or excessive mucocutaneous bleeding.

Venous thrombosis: For splanchnic or cerebral venous thrombosis, treatment often includes LMWH for 1-3 months followed by long-term anticoagulation with vitamin K antagonists or DOACs indefinitely unless risk-benefit changes.

Management Guidelines for Essential Thrombocythemia based on IPSET-T (International Prognostic Score of Thrombosis in World Health Organization–Essential Thrombocytopenia), NCCN (National Comprehensive Cancer Network) and ELN (European Leukemia Net)

Surgery

Surgical intervention is not recommended for the management of essential thrombocytosis.

Perioperative management should have a multidisciplinary approach involving hematology and the surgical team. Some experts target preprocedure platelet counts <450 x 10^9/L in high-risk and <600 x 10^9/L in low-risk patients. Achieving the low-risk target may require a short course of hydroxyurea.[25]

Evidence is lacking for perioperative aspirin/anticoagulation decisions specific to ET, so experts recommend following general perioperative guidelines for people without ET.

Primary Prevention

There is no established method for primary prevention of Essential thrombocytosis.

Secondary Prevention

Secondary prevention strategy following essential thrombocytosis include low dose aspirin therapy.

References

  1. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  2. ↑ 2.0 2.1 Steven Sanchez & April Ewton (2006). “Essential thrombocythemia: a review of diagnostic and pathologic features”. Archives of pathology & laboratory medicine. 130 (8): 1144–1150. PMID 16879015. Unknown parameter |month= ignored (help)
  3. ↑ Levine, R. L.; Gilliland, D. G. (2008). “Myeloproliferative disorders”. Blood. 112 (6): 2190–2198. doi:10.1182/blood-2008-03-077966. ISSN 0006-4971.
  4. ↑ 4.0 4.1 4.2 4.3 Fabris F, Randi ML (2009). “Essential thrombocythemia: past and present”. Intern Emerg Med. 4 (5): 381–8. doi:10.1007/s11739-009-0284-x. PMID 19636672.
  5. ↑ 5.0 5.1 Essential Thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia. Accessed on October 29, 2015
  6. ↑ 6.0 6.1 6.2 Essential Thrombocythemia (ET). MPN Research foundation. http://www.mpnresearchfoundation.org/Essential-Thrombocythemia Accessed on November 15, 2015.
  7. ↑ 7.0 7.1 7.2 Brière JB (2007). “Essential thrombocythemia”. Orphanet J Rare Dis. 2: 3. doi:10.1186/1750-1172-2-3. PMC 1781427. PMID 17210076.
  8. ↑ 8.0 8.1 8.2 8.3 Schmoldt A, Benthe HF, Haberland G (1975). “Digitoxin metabolism by rat liver microsomes”. Biochem Pharmacol. 24 (17): 1639–41. PMID http://dx.doi.org/10.1182/blood-2007-04-083501 Check |pmid= value (help).
  9. ↑ Trifa, Adrian P.; Cucuianu, Andrei; Popp, Radu A. (2014). “Familial Essential Thrombocythemia Associated withMPLW515L Mutation in Father andJAK2V617F Mutation in Daughter”. Case Reports in Hematology. 2014: 1–3. doi:10.1155/2014/841787. ISSN 2090-6560.
  10. ↑ Essential thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia Accessed on November 16, 2015.
  11. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  12. ↑ 12.0 12.1 Beer PA, Erber WN, Campbell PJ, Green AR (2011). “How I treat essential thrombocythemia”. Blood. 117 (5): 1472–82. doi:10.1182/blood-2010-08-270033. PMC 3145107. PMID 21106990.
  13. ↑ The Asco Post. JAK2 and MPL Mutation Screening: What Are the Indications and How to Interpret the Results. http://www.ascopost.com/issues/february-15-2012/jak2-and-mpl-mutation-screening-what-are-the-indications-and-how-to-interpret-the-results.aspx
  14. ↑ Tefferi A, Noel P, Hanson CA (2011). “Uses and abuses of JAK2 and MPL mutation tests in myeloproliferative neoplasms a paper from the 2010 William Beaumont hospital symposium on molecular pathology”. J Mol Diagn. 13 (5): 461–6. doi:10.1016/j.jmoldx.2011.05.007. PMC 3157620. PMID 21723416.
  15. ↑ Essential Thrombocytosis Differential Diagnoses. Medscape. http://emedicine.medscape.com/article/206697-differential Accessed on November 12, 2015.
  16. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  17. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  18. ↑ Frewin, R (October 2012). “Headache in essential thrombocythaemia” (PDF). International Journal of Clinical Practice. 66 (10): 976–83. doi:10.1111/j.1742-1241.2012.02986.x. PMC 3469735. PMID 22889110. Unknown parameter |coauthors= ignored (help)
  19. ↑ Tefferi, A (March 2011). “Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management”. American Journal of Hematology. 86 (3): 292–301. doi:10.1002/ajh.21946. PMID 21351120.
  20. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  21. ↑ Essential Thrombocythemia. Merck manual. http://www.merckmanuals.com/professional/hematology-and-oncology/myeloproliferative-disorders/essential-thrombocythemia. Accessed on November 11,2015.
  22. ↑ 22.0 22.1 Arampatzis, Spyridon; Stefanidis, Ioannis; Lakiopoulos, Vassilios; Raio, Luigi; Surbek, Daniel; Mohaupt, Markus G (2010). “Postpartal recurrent non-ST elevation myocardial infarction in essential thrombocythaemia: case report and review of the literature”. Thrombosis Journal. 8 (1): 12. doi:10.1186/1477-9560-8-12. ISSN 1477-9560.
  23. ↑ How I treat symptomatic splenomegaly in patients with myelofibrosis. Blood journal. http://www.bloodjournal.org/content/113/22/5394?sso-checked=true Accessed on November 17, 2015.
  24. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  25. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).


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Historical Perspective

Historical Perspective

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Overview

Essential thrombocytosis was first defined by Emil Epstein and Alfred Goedel, two Austrian pathologists, in the year 1934 and was initially called hemorrhagic thrombocythemia.[1]

Historical perspective

  • Essential thrombocytosis was first defined by Emil Epstein and Alfred Goedel, two Austrian pathologists, in the year 1934 and was initially called hemorrhagic thrombocythemia.[1]
  • Subsequently, essential thrombocytosis was classified as a myeloproliferative disorder along with chronic myelogenous leukemia (CML), polycythemia vera (PV), and chronic idiopathic myelofibrosis (CIMF).

References

  1. ↑ 1.0 1.1 Steven Sanchez & April Ewton (2006). “Essential thrombocythemia: a review of diagnostic and pathologic features”. Archives of pathology & laboratory medicine. 130 (8): 1144–1150. PMID 16879015. Unknown parameter |month= ignored (help)


Template:WikiDoc Sources

Classification

Classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Overview

There is no classification system established for essential thrombocytosis. However, a familial form of essential thrombocytosis has been previously reported.[1]

Classification

  • There is no classification system established for essential thrombocytosis. However, essential thrombocytosis may be broadly classified into two types:[1]
    • Sporadic
      • The majority of cases remain sporadic.
    • Genetic
      • Inheritance is in an autosomal dominant fashion with incomplete penetrance.

References

  1. ↑ 1.0 1.1 Trifa, Adrian P.; Cucuianu, Andrei; Popp, Radu A. (2014). “Familial Essential Thrombocythemia Associated withMPLW515L Mutation in Father andJAK2V617F Mutation in Daughter”. Case Reports in Hematology. 2014: 1–3. doi:10.1155/2014/841787. ISSN 2090-6560.


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Pathophysiology

Pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2] Parth Vikram Singh, MBBS[3]

Overview

Essential thrombocytosis arises from hematopoietic stem cells which give rise to megakaryocytes which give rise to platelets (thrombocytes), that are normally involved in blood clotting. Development of essential thrombocytosis is the result of a genetic mutation in the janus kinase 2 (JAK2) gene in >50% of the patients. Other genes that may be involved in the pathogenesis of essential thrombocytosis are CALR, MPL, and THPO genes.[1] Approximately 90% of patients have JAK-STAT pathway driver variants: JAK2 (64%), CALR (23%), and MPL (4%). About 10% are triple-negative (no JAK2/CALR/MPL variant).[2] On microscopic histopathological analysis, thrombocytosis, bone marrow hyperplasia with hyperlobated megakaryotic nuclei evident of thrombopoiesis are characteristic findings of essential thrombocytosis.

Pathophysiology

  • Essential thrombocytosis arises from pluripotent hematopoietic stem cells of megakaryocytic lineage that give rise to platelets.[3]
  • Essential thrombocytosis is caused by point mutations in janus kinase 2 (JAK2) gene in >50% of the patients. Approximately 90% of patients have JAK-STAT pathway driver variants: JAK2 (64%), CALR (23%), and MPL (4%). About 10% are triple-negative (no JAK2/CALR/MPL variant).[4]
  • Thrombopoietin destruction is also critical to the development of essential thrombocytosis.
    • Thrombopoietin normally regulates the stimulation, production, and proliferation of megakaryocytes.[5]
    • Despite the high platelet count, essential thrombocytosis paradoxically manifests with an increase in free circulating concentration of thrombopoietin as the abnormal platelets have defective thrombopoietin receptors which impair proper binding of thrombopoietin.[6]
  • Platelets contain different types of granules: alpha (contain P-selectin, platelet factor 4, transforming growth factor-β1, platelet-derived growth factor, fibronectin, B-thromboglobulin, vWF, fibrinogen, and coagulation factors V and XIII), delta (δ) or dense granules (contain ADP or ATP, calcium, and serotonin), gamma (γ), and lambda (λ) granules[7].
    • With defective granules in essential thrombocytosis, there is a deficiency in clotting factors like fibrinogen and von Willebrand (vWF), which impairs the process of aggregation.
    • On the other hand, patients with secondary or reactive thrombocytosis have normal platelet activity with no defects in aggregation.
  • CFU-Me (pluripotential hemopoietic stem cell or hemocytoblast) to the formation of megakaryocyte.[8]
    CFU-Me (pluripotential hemopoietic stem cell or hemocytoblast) to the formation of megakaryocyte.[8]

Genetics

  • Essential thrombocytosis is associated with mutations in janus kinase 2 (JAK2) gene in >50% of the patients.
  • Janus kinase 2, a non-receptor tyrosine kinase protein belonging to the janus kinase family, helps in signaling pathways involved in hematopoiesis (including thrombopoietin, erythropoietin, granulocyte-colony stimulating factor, Bcl-2, and interleukin-3,5).[9]
    • A point mutation from G to T that results in the substitution of valine for phenylalanine at amino acid 617 of the JAK2 protein first activates the tyrosine kinase in JAK2 and subsequently results in the activation of the JAK-STAT pathway.
    • Activation of the JAK-STAT pathway results in abnormal differentiation and proliferation of the precursor cells, releasing the increased pool of platelets into the circulation.[10]
  • Mutations in the calreticulin (CALR) gene has been identified in patients with essential thrombocytosis who lacked JAK2 mutations.[11]
    • The mechanism by which the mutation triggers the disease remains unknown.
  • MPL (myeloproliferative leukemia protein) and THPO (thrombopoietin) gene mutations may also result in the activation of JAK-STAT pathway, causing abnormal platelet proliferation.[12]

Microscopic Pathology

  • A complete blood count shows marked elevation of platelet count greater than or equal to 600,000/μL of blood and sometimes even higher.
  • The platelet shape and size usually remain unchanged, but variations may occur.
  • The red cell morphology depends on the presence and severity of bleeding.
  • The white cell count remains slightly elevated.
  • Bone marrow biopsy is the definitive diagnostic test for essential thrombocytosis. The bone marrow is usually hypercellular, though it can be normocellular. The megakaryocytes are bigger in size and have hyperlobated nuclei which is the characteristic feature of increased thrombopoiesis. Cells are usually stainable with iron, provided the patient had no significant hemorrhagic events. Collagen fibrosis is typically absent.[3]
  • This represents a platelet count between 1.5 and 2 million per microliter (normal range is between 0.150 and 0.450 million). The patient had had an elevated count for at least 15 years but is asymptomatic.[13]
    This represents a platelet count between 1.5 and 2 million per microliter (normal range is between 0.150 and 0.450 million). The patient had had an elevated count for at least 15 years but is asymptomatic.[13]
  • Histopathological image representing a bone marrow aspirate in a patient with essential thrombocythemia. Hematoxylin & eosin stain.[14]
    Histopathological image representing a bone marrow aspirate in a patient with essential thrombocythemia. Hematoxylin & eosin stain.[14]

References

  1. ↑ Essential thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia Accessed on November 16, 2015.
  2. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  3. ↑ 3.0 3.1 Sanchez S, Ewton A (2006). [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi? dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16879015 “Essential thrombocythemia: a review of diagnostic and pathologic features”] Check |url= value (help). Arch Pathol Lab Med. 130 (8): 1144–50. doi:10.1043/1543-2165(2006)130[1144:ET]2.0.CO;2. PMID 16879015 PMID: 16879015 Check |pmid= value (help). line feed character in |url= at position 54 (help)
  4. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  5. ↑ Thrombopoietin. Wikipedia. https://en.wikipedia.org/wiki/Thrombopoietin#Function_and_regulation. Accessed on Novenber 3rd,2015.
  6. ↑ J. Li, Y. Xia & D. J. Kuter (2000). “The platelet thrombopoietin receptor number and function are markedly decreased in patients with essential thrombocythaemia”. British journal of haematology. 111 (3): 943–953. PMID 11122159. Unknown parameter |month= ignored (help)
  7. ↑ Platelet. Wikipedia.https://en.wikipedia.org/wiki/Platelet#Granule_secretion. Accessed on Novenber 3rd,2015.
  8. ↑ Megakaryocyte. Wikipedia. https://en.wikipedia.org/wiki/Megakaryocyte#/media/File:Illu_blood_cell_lineage.jpg Accessed on November 16,2015.
  9. ↑ Jones AV, Kreil S, Zoi K, Waghorn K, Curtis C, Zhang L; et al. (2005). “Widespread occurrence of the JAK2 V617F mutation in chronic myeloproliferative disorders”. Blood. 106 (6): 2162–8. doi:10.1182/blood-2005-03-1320. PMID 15920007.
  10. ↑ Essential thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia Accessed on November 16, 2015.
  11. ↑ Rotunno, G.; Mannarelli, C.; Guglielmelli, P.; Pacilli, A.; Pancrazzi, A.; Pieri, L.; Fanelli, T.; Bosi, A.; Vannucchi, A. M. (2013). “Impact of calreticulin mutations on clinical and hematological phenotype and outcome in essential thrombocythemia”. Blood. 123 (10): 1552–1555. doi:10.1182/blood-2013-11-538983. ISSN 0006-4971.
  12. ↑ Essential thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia Accessed on November 16, 2015.
  13. ↑ File:Essential Thrombocythemia, Peripheral Blood (10189570483).jpg. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:Essential_Thrombocythemia,_Peripheral_Blood_(10189570483).jpg Accessed on November 12, 2015.
  14. ↑ File:Essential thrombocythemia (1).jpg. Wikimedia commons. https://commons.wikimedia.org/wiki/File:Essential_thrombocythemia_(1).jpg Accessed on November 12, 2015.


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Epidemiology and Demographics

Epidemiology and Demographics

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]Parth Vikram Singh, MBBS[3]

Overview

The incidence of essential thrombocytosis is approximately 0.6-2.5 cases per 100,000 individuals worldwide annually.[1] The prevalence of essential thrombocytosis is about 30 for every 100,000 people worldwide.[2] The incidence of essential thrombocytosis increases with age; the median age at diagnosis is 65-70 years. Patients of all age groups may develop essential thrombocytosis. However it commonly affects individuals older than 60 years of age.[3] Females are more commonly affected with essential thrombocytosis than males.[3] The female to male ratio is approximately 2 to 1.[1]

Epidemiology

Incidence

  • The annual incidence of essential thrombocytosis is estimated to be 0.6-2.5 cases per 100,000 individuals worldwide.[1]
  • The annual incidence rate of ET in the US is 1.5 per 100,000 persons (age-standardized incidence 1.6 per 100,000 in a Swedish population-based study). The median age at diagnosis is 59 years.[4]
  • In reality, the incidence may be much more higher attributing the incidental diagnosis of the condition where many go undiagnosed due to lack of routine medical care.

Prevalence

  • Worldwide, the prevalence of essential thrombocytosis is approximately 30 for every 100,000 individuals worldwide.[2].

Age

  • Patients of all age groups may develop essential thrombocytosis. However it commonly affects individuals older than 60 years of age.[3]
  • The median age at onset is 65-70 years.

Gender

  • Women in their third decade of life are more commonly affected with essential thrombocytosis than men at same age. The female to male ratio is approximately 2:1.[5]
  • Patients who present in the 6th decade of life usually have same incidence in both men and women.

References

  1. ↑ 1.0 1.1 1.2 Fabris F, Randi ML (2009). “Essential thrombocythemia: past and present”. Intern Emerg Med. 4 (5): 381–8. doi:10.1007/s11739-009-0284-x. PMID 19636672.
  2. ↑ 2.0 2.1 Essential Thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia. Accessed on October 29, 2015
  3. ↑ 3.0 3.1 3.2 Essential Thrombocythemia (ET). MPN Research foundation. http://www.mpnresearchfoundation.org/Essential-Thrombocythemia Accessed on November 15, 2015.
  4. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  5. ↑ Brière JB (2007). “Essential thrombocythemia”. Orphanet J Rare Dis. 2: 3. doi:10.1186/1750-1172-2-3. PMC 1781427. PMID 17210076.


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Risk Factors

Risk Factors

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]Parth Vikram Singh, MBBS[3]

Overview

The incidence of essential thrombocytosis is approximately 0.6-2.5 cases per 100,000 individuals worldwide annually.[1] The prevalence of essential thrombocytosis is about 30 for every 100,000 people worldwide.[2] The incidence of essential thrombocytosis increases with age; the median age at diagnosis is 65-70 years. Patients of all age groups may develop essential thrombocytosis. However it commonly affects individuals older than 60 years of age.[3] Females are more commonly affected with essential thrombocytosis than males.[3] The female to male ratio is approximately 2 to 1.[1]

Epidemiology

Incidence

  • The annual incidence of essential thrombocytosis is estimated to be 0.6-2.5 cases per 100,000 individuals worldwide.[1]
  • The annual incidence rate of ET in the US is 1.5 per 100,000 persons (age-standardized incidence 1.6 per 100,000 in a Swedish population-based study). The median age at diagnosis is 59 years.[4]
  • In reality, the incidence may be much more higher attributing the incidental diagnosis of the condition where many go undiagnosed due to lack of routine medical care.

Prevalence

  • Worldwide, the prevalence of essential thrombocytosis is approximately 30 for every 100,000 individuals worldwide.[2].

Age

  • Patients of all age groups may develop essential thrombocytosis. However it commonly affects individuals older than 60 years of age.[3]
  • The median age at onset is 65-70 years.

Gender

  • Women in their third decade of life are more commonly affected with essential thrombocytosis than men at same age. The female to male ratio is approximately 2:1.[5]
  • Patients who present in the 6th decade of life usually have same incidence in both men and women.

References

  1. ↑ 1.0 1.1 1.2 Fabris F, Randi ML (2009). “Essential thrombocythemia: past and present”. Intern Emerg Med. 4 (5): 381–8. doi:10.1007/s11739-009-0284-x. PMID 19636672.
  2. ↑ 2.0 2.1 Essential Thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia. Accessed on October 29, 2015
  3. ↑ 3.0 3.1 3.2 Essential Thrombocythemia (ET). MPN Research foundation. http://www.mpnresearchfoundation.org/Essential-Thrombocythemia Accessed on November 15, 2015.
  4. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  5. ↑ Brière JB (2007). “Essential thrombocythemia”. Orphanet J Rare Dis. 2: 3. doi:10.1186/1750-1172-2-3. PMC 1781427. PMID 17210076.


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Screening

Screening

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Overview

Screening for essential thrombocytosis by cell-based quantitative assays for JAK2V617F mutation is recommended among individuals with a positive family history for the disease (autosomal dominant inheritance) and in patients who present with thrombocytosis, erythrocytosis, and monocytosis.[1][2]

Screening

Screening for essential thrombocytosis by cell-based quantitative assays for JAK2V617F mutation is recommended among the following:[1][2]

References

  1. ↑ 1.0 1.1 The Asco Post. JAK2 and MPL Mutation Screening: What Are the Indications and How to Interpret the Results. http://www.ascopost.com/issues/february-15-2012/jak2-and-mpl-mutation-screening-what-are-the-indications-and-how-to-interpret-the-results.aspx
  2. ↑ 2.0 2.1 Tefferi A, Noel P, Hanson CA (2011). “Uses and abuses of JAK2 and MPL mutation tests in myeloproliferative neoplasms a paper from the 2010 William Beaumont hospital symposium on molecular pathology”. J Mol Diagn. 13 (5): 461–6. doi:10.1016/j.jmoldx.2011.05.007. PMC 3157620. PMID 21723416.


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Causes

Causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]Parth Vikram Singh, MBBS[3]

Overview

Essential thrombocytosis may be caused by a mutation in the janus kinase 2 (JAK2) gene (in >50% of the patients), CALR, MPL, or THPO genes. Approximately 90% of patients have JAK-STAT pathway driver variants: JAK2 (64%), CALR (23%), and MPL (4%). About 10% are triple-negative (no JAK2/CALR/MPL variant).[1]

Causes

Essential thrombocytosis may be caused by a mutation in one of the following genes:[2]

Approximately 90% of patients have JAK-STAT pathway driver variants: JAK2 (64%), CALR (23%), and MPL (4%). About 10% are triple-negative (no JAK2/CALR/MPL variant).

References

  1. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  2. ↑ Essential thrombocythemia. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/essential-thrombocythemia Accessed on November 16, 2015.


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Differentiating Essential thrombocytosis from other Diseases

Differentiating Essential thrombocytosis from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Hannan Javed, M.D.[2] Zahir Ali Shaikh, MD[3] Soujanya Thummathati, MBBS [4]Parth Vikram Singh, MBBS

Overview

Essential thrombocytosis must be differentiated from other causes of thrombocytosis, such as chronic myelogenous leukemia (CML), myelodysplastic syndrome, polycythemia vera, primary myelofibrosis, secondary thrombocytosis.[1]

Differentiating Myeloproliferative Disorders

ABBREVIATIONS

N/A: Not available, NL: Normal, FISH: Fluorescence in situ hybridization, PCR: Polymerase chain reaction, LDH: Lactate dehydrogenase, PUD: Peptic ulcer disease, EPO: Erythropoietin, LFTs: Liver function tests, RFTs: Renal function tests, LAP: Leukocyte alkaline phosphatase, LAD: Leukocyte alkaline dehydrgenase, WBCs: White blood cells.

Myeloproliferative neoplasms (MPN) Clinical manifestations Diagnosis Other features
Symptoms Physical examination CBC & Peripheral smear Bone marrow biopsy Other investigations
WBCs Hb Plat-
elets
Leuko-cytes Blasts Left
shift 		Baso-
phils 		Eosino-
phils 		Mono-
cytes 		Others
Chronic myeloid leukemia
(CML), BCR-ABL1+[2][3] 		↑ <2% + ↑ ↑ ↑ N/A ↓ NL
Chronic neutrophilic leukemia (CNL)[4][5][6] ↑ Minimal + NL NL NL ↓ ↓
Polycythemia vera
(PV)[7][8][9][10]
  • Constitutional
 NL or ↑ None – ↑ or ↓ NL or ↑ NL ↑↑ NL
  • Hypercellularity for age with tri-lineage growth
Primary myelofibrosis (PMF)[11][12][13][14] ↓ Erythroblasts – Absent NL NL ↓ ↓
  • Variable with fibrosis or hypercellularity
Essential thrombocythemia (ET)[15][16][17]

NL or ↑

None

–

↓ or absent

NL

NL

  • N/A

↓

↑↑

  • Normal/Hypercellular
Chronic eosinophilic leukemia,
not otherwise specified
(NOS)[18][19][20][21] 		↑ Present + ↑ ↑↑ ↑ ↓ ↓
MPN,
unclassifiable 		↑ Variable ± ↑ or ↓ ↑ or ↓ ↑ or ↓ ↓ ↑
  • N/A
Mastocytosis[22][23][24][25]
  • Constitutional
 ↑ None – NL ↑ NL ↓ ↓ or ↑
Myeloid/lymphoid neoplasms
with eosinophilia and rearrangement
of PDGFRA, PDGFRB, or FGFR1,
or with PCM1–JAK2[26][27][28][29] 		↑ NL – NL ↑ ↑
  • None
 NL ↓
  • FISH shows t(8;13) and t(8;22)
B-lymphoblastic leukemia/lymphoma[30][31] NL or ↑ >25% N/A ↑ or ↓ ↑ or ↓ ↑ or ↓ ↓ ↓
Myelodysplastic syndromes
(MDS)[32][33] 		↓ Variable – ↓ ↓ ↓ ↓ ↓
  • Leukemia transformation
  • Acquired pseudo-Pelger-Huët anomaly
Acute myeloid leukemia (AML)
and related neoplasms[34][35] 		NL or ↑ ↑ N/A ↑ or ↓ ↑ or ↓ ↑ or ↓ ↓ ↓

with dysplasia

Blastic plasmacytoid
dendritic cell neoplasm[36][37][38][39] 		NL ↑ NL NL NL ↓ ↓
Myelodysplastic
/myeloproliferative
neoplasms (MDS/MPN) 		Chronic myelomonocytic leukemia (CMML)[40]
[41][42]
 ↑ < 20% NL ↑ ↑↑ ↓ ↓
  • Overlapping of both, MDS and MPN
  • Absolute monocytosis > 1 × 109/L (defining feature)
  • MD-CMML:WBC ≤ 13 × 109/L (FAB)
  •  MP-CMML:WBC > 13 × 109/L (FAB)
Atypical chronic myeloid leukemia (aCML), BCR-ABL1-[43][44] ↑ <20% + <2% of WBCs N/A N/A
  • N/A
 ↓ ↓
Juvenile myelomonocytic leukemia (JMML)[45][46] ↑ ↑ N/A N/A N/A ↑ ↓ ↓
MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T)[47][48][49]
  • Variable
 NL or ↑ NL – NL N/A N/A ↓ ↑
T-lymphoblastic leukemia/
lymphoma
T-lymphoblastic leukemia/
lymphoma[50][51][52] 		↑ >25% blasts (Leukemia)

<25% blasts (Lymphoma)

± ↑ or ↓ ↑ or ↓ ↑ or ↓
  • ↑ LDH
  • Positive for TdT
 ↓ ↓
  • Hypercelluarity with increased T cells precursors
Provisional entity: Natural killer (NK) cell lymphoblastic leukemia/lymph[53] ↑ ↑ ± ↑ or ↓ ↑ or ↓ ↑ or ↓ ↓ ↓
  • N/A
Provisional entity: Early T-cell precursor lymphoblastic leukemia[54][55] ↑ ↑ ± ↑ or ↓ ↑ or ↓ ↑ or ↓ ↓ ↓
  • Hypercelluarity with increased T cells precursors

Secondary causes account for >85% of thrombocytosis; exclude secondary thrombocytosis before diagnosing ET.

Table: ET vs secondary thrombocytosis[56]

Feature Suggests ET Suggests secondary thrombocytosis
Clinical clues Microcirculatory symptoms like s include erythromelalgia, acral paresthesias, burning toes and fingers, blurred vision, or headaches (~29%);

thrombosis history (~22%);

splenomegaly (~12%);

splanchnic vein thrombosis (~5%);

Superficial thrombophlebitis (<5%);

cerebral vein thrombosis (<2%)

Symptoms/signs of infection/inflammation/malignancy;

recent trauma/surgery;

prior splenectomy;

iron deficiency

Exam Palpable splenomegaly Absence of splenomegaly
Labs Sustained thrombocytosis; JAK2/CALR/MPL variant detected New-onset thrombocytosis;

positive blood culture;

neutrophilia/left shift;

elevated CRP/ESR;

iron deficiency;

functional asplenia markers (Howell-Jolly bodies, nucleated RBCs)

Treatment note – No evidence supports routine aspirin/anticoagulation/cytoreduction/plateletpheresis for reactive thrombocytosis regardless of platelet count

Table: Common causes of secondary thrombocytosis [57]

Cause (percent representation) Mechanism Typical management
Infections (17%-43%) Inflammatory cytokines; nonspecific stimulation; platelet release Resolves with treatment; may persist with chronic infection
Inflammatory diseases (4%-12%) Increased thrombopoietic factors Treat underlying condition
Malignancy (10%) (eg, lung/GI/lymphomas) Increased thrombopoietic factors Treat underlying malignancy
Iron deficiency (7%-11%) Increased progenitor proliferation Replete iron; typically resolves in 1-2 months
Splenectomy (1%-2%) Decreased sequestration/turnover; peak 1-3 weeks May be lifelong; may resolve in 1-5 years
Surgery/trauma (22%-32%) Increased thrombopoietic factors from tissue damage Resolves in days to weeks
Rebound thrombocytosis (7%) Recovery from chemotherapy; cessation of excess alcohol; vitamin deficiency/ITP treatment Resolves in 2-4 weeks
Drugs (1%-3%) Medication-related Dose modify/stop (variable)


References

  1. ↑ Essential Thrombocytosis Differential Diagnoses. Medscape. http://emedicine.medscape.com/article/206697-differential Accessed on November 12, 2015.
  2. ↑ Savage DG, Szydlo RM, Goldman JM (January 1997). “Clinical features at diagnosis in 430 patients with chronic myeloid leukaemia seen at a referral centre over a 16-year period”. Br. J. Haematol. 96 (1): 111–6. PMID 9012696.
  3. ↑ Thompson PA, Kantarjian HM, Cortes JE (October 2015). “Diagnosis and Treatment of Chronic Myeloid Leukemia in 2015”. Mayo Clin. Proc. 90 (10): 1440–54. doi:10.1016/j.mayocp.2015.08.010. PMC 5656269. PMID 26434969.
  4. ↑ Szuber N, Tefferi A (February 2018). “Chronic neutrophilic leukemia: new science and new diagnostic criteria”. Blood Cancer J. 8 (2): 19. doi:10.1038/s41408-018-0049-8. PMC 5811432. PMID 29440636.
  5. ↑ Maxson JE, Tyner JW (February 2017). “Genomics of chronic neutrophilic leukemia”. Blood. 129 (6): 715–722. doi:10.1182/blood-2016-10-695981. PMC 5301820. PMID 28028025.
  6. ↑ Menezes J, Cigudosa JC (2015). “Chronic neutrophilic leukemia: a clinical perspective”. Onco Targets Ther. 8: 2383–90. doi:10.2147/OTT.S49688. PMC 4562747. PMID 26366092.
  7. ↑ Vannucchi AM, Guglielmelli P, Tefferi A (March 2018). “Polycythemia vera and essential thrombocythemia: algorithmic approach”. Curr. Opin. Hematol. 25 (2): 112–119. doi:10.1097/MOH.0000000000000402. PMID 29194068.
  8. ↑ Pillai AA, Babiker HM. PMID 30252337. Missing or empty |title= (help)
  9. ↑ Tefferi A, Barbui T (January 2019). “Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management”. Am. J. Hematol. 94 (1): 133–143. doi:10.1002/ajh.25303. PMID 30281843.
  10. ↑ Rumi E, Cazzola M (February 2017). “Diagnosis, risk stratification, and response evaluation in classical myeloproliferative neoplasms”. Blood. 129 (6): 680–692. doi:10.1182/blood-2016-10-695957. PMC 5335805. PMID 28028026.
  11. ↑ Cervantes F, Correa JG, Hernandez-Boluda JC (May 2016). “Alleviating anemia and thrombocytopenia in myelofibrosis patients”. Expert Rev Hematol. 9 (5): 489–96. doi:10.1586/17474086.2016.1154452. PMID 26891375.
  12. ↑ Hoffman, Ronald (2018). Hematology : basic principles and practice. Philadelphia, PA: Elsevier. ISBN 9780323357623.
  13. ↑ Michiels JJ, Bernema Z, Van Bockstaele D, De Raeve H, Schroyens W (March 2007). “Current diagnostic criteria for the chronic myeloproliferative disorders (MPD) essential thrombocythemia (ET), polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF)”. Pathol. Biol. 55 (2): 92–104. doi:10.1016/j.patbio.2006.06.002. PMID 16919893.
  14. ↑ Hoffman, Ronald (2018). Hematology : basic principles and practice. Philadelphia, PA: Elsevier. ISBN 9780323357623.
  15. ↑ Schmoldt A, Benthe HF, Haberland G (1975). “Digitoxin metabolism by rat liver microsomes”. Biochem Pharmacol. 24 (17): 1639–41. PMID http://dx.doi.org/10.1182/blood-2007-04-083501 Check |pmid= value (help).
  16. ↑ Daniel A. Arber, Attilio Orazi, Robert Hasserjian, Jurgen Thiele, Michael J. Borowitz, Michelle M. Le Beau, Clara D. Bloomfield, Mario Cazzola & James W. Vardiman (2016). “The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia”. Blood. 127 (20): 2391–2405. doi:10.1182/blood-2016-03-643544. PMID 27069254. Unknown parameter |month= ignored (help)
  17. ↑ A. Tefferi, R. Fonseca, D. L. Pereira & H. C. Hoagland (2001). “A long-term retrospective study of young women with essential thrombocythemia”. Mayo Clinic proceedings. 76 (1): 22–28. doi:10.4065/76.1.22. PMID 11155408. Unknown parameter |month= ignored (help)
  18. ↑ Vidyadharan S, Joseph B, Nair SP (2016). “Chronic Eosinophilic Leukemia Presenting Predominantly with Cutaneous Manifestations”. Indian J Dermatol. 61 (4): 437–9. doi:10.4103/0019-5154.185716. PMC 4966405. PMID 27512192.
  19. ↑ Hofmans M, Delie A, Vandepoele K, Van Roy N, Van der Meulen J, Philippé J, Moors I (2018). “A case of chronic eosinophilic leukemia with secondary transformation to acute myeloid leukemia”. Leuk Res Rep. 9: 45–47. doi:10.1016/j.lrr.2018.04.001. PMC 5993353. PMID 29892549.
  20. ↑ Yamada Y, Rothenberg ME, Cancelas JA (2006). “Current concepts on the pathogenesis of the hypereosinophilic syndrome/chronic eosinophilic leukemia”. Transl Oncogenomics. 1: 53–63. PMC 3642145. PMID 23662039.
  21. ↑ Kim TH, Gu HJ, Lee WI, Lee J, Yoon HJ, Park TS (September 2016). “Chronic eosinophilic leukemia with FIP1L1-PDGFRA rearrangement”. Blood Res. 51 (3): 204–206. doi:10.5045/br.2016.51.3.204. PMID 27722133.
  22. ↑ Carter MC, Metcalfe DD, Komarow HD (February 2014). “Mastocytosis”. Immunol Allergy Clin North Am. 34 (1): 181–96. doi:10.1016/j.iac.2013.09.001. PMC 3863935. PMID 24262698.
  23. ↑ Macri A, Cook C. PMID 29494109. Missing or empty |title= (help)
  24. ↑ Lladó AC, Mihon CE, Silva M, Galzerano A (2014). “Systemic mastocytosis – a diagnostic challenge”. Rev Bras Hematol Hemoter. 36 (3): 226–9. doi:10.1016/j.bjhh.2014.03.003. PMC 4109736. PMID 25031064.
  25. ↑ Valent P, Akin C, Metcalfe DD (March 2017). “Mastocytosis: 2016 updated WHO classification and novel emerging treatment concepts”. Blood. 129 (11): 1420–1427. doi:10.1182/blood-2016-09-731893. PMC 5356454. PMID 28031180.
  26. ↑ Kumar, Kirthi R.; Chen, Weina; Koduru, Prasad R.; Luu, Hung S. (2015). “Myeloid and Lymphoid Neoplasm With Abnormalities of FGFR1 Presenting With Trilineage Blasts and RUNX1 Rearrangement”. American Journal of Clinical Pathology. 143 (5): 738–748. doi:10.1309/AJCPUD6W1JLQQMNA. ISSN 1943-7722.
  27. ↑ Paolo Strati, Guilin Tang, Dzifa Y. Duose, Saradhi Mallampati, Rajyalakshmi Luthra, Keyur P. Patel, Mohammad Hussaini, Abu-Sayeef Mirza, Rami S. Komrokji, Stephen Oh, John Mascarenhas, Vesna Najfeld, Vivek Subbiah, Hagop Kantarjian, Guillermo Garcia-Manero, Srdan Verstovsek & Naval Daver (2018). “Myeloid/lymphoid neoplasms with FGFR1 rearrangement”. Leukemia & lymphoma. 59 (7): 1672–1676. doi:10.1080/10428194.2017.1397663. PMID 29119847. Unknown parameter |month= ignored (help)
  28. ↑ Ximena Montenegro-Garreaud, Roberto N. Miranda, Alexandra Reynolds, Guilin Tang, Sa A. Wang, Mariko Yabe, Wei Wang, Lianghua Fang, Carlos E. Bueso-Ramos, Pei Lin, L. Jeffrey Medeiros & Xinyan Lu (2017). “Myeloproliferative neoplasms with t(8;22)(p11.2;q11.2)/BCR-FGFR1: a meta-analysis of 20 cases shows cytogenetic progression with B-lymphoid blast phase”. Human pathology. 65: 147–156. doi:10.1016/j.humpath.2017.05.008. PMID 28551329. Unknown parameter |month= ignored (help)
  29. ↑ Paola Villafuerte-Gutierrez, Montserrat Lopez Rubio, Pilar Herrera & Eva Arranz (2018). “A Case of Myeloproliferative Neoplasm with BCR-FGFR1 Rearrangement: Favorable Outcome after Haploidentical Allogeneic Transplantation”. Case reports in hematology. 2018: 5724960. doi:10.1155/2018/5724960. PMID 30647980.
  30. ↑ Kamiya-Matsuoka C, Garciarena P, Amin HM, Tremont-Lukats IW, de Groot JF (December 2013). “B lymphoblastic leukemia/lymphoma presenting as seventh cranial nerve palsy”. Neurol Clin Pract. 3 (6): 532–534. doi:10.1212/CPJ.0b013e3182a78ef0. PMC 6082360. PMID 30107017.
  31. ↑ Zhang X, Rastogi P, Shah B, Zhang L (September 2017). “B lymphoblastic leukemia/lymphoma: new insights into genetics, molecular aberrations, subclassification and targeted therapy”. Oncotarget. 8 (39): 66728–66741. doi:10.18632/oncotarget.19271. PMC 5630450. PMID 29029550.
  32. ↑ Germing U, Kobbe G, Haas R, Gattermann N (November 2013). “Myelodysplastic syndromes: diagnosis, prognosis, and treatment”. Dtsch Arztebl Int. 110 (46): 783–90. doi:10.3238/arztebl.2013.0783. PMC 3855821. PMID 24300826.
  33. ↑ Gangat N, Patnaik MM, Tefferi A (January 2016). “Myelodysplastic syndromes: Contemporary review and how we treat”. Am. J. Hematol. 91 (1): 76–89. doi:10.1002/ajh.24253. PMID 26769228.
  34. ↑ Islam A, Catovsky D, Goldman JM, Galton DA (September 1985). “Bone marrow biopsy changes in acute myeloid leukaemia. I: Observations before chemotherapy”. Histopathology. 9 (9): 939–57. PMID 3864727.
  35. ↑ Orazi A (2007). “Histopathology in the diagnosis and classification of acute myeloid leukemia, myelodysplastic syndromes, and myelodysplastic/myeloproliferative diseases”. Pathobiology. 74 (2): 97–114. doi:10.1159/000101709. PMID 17587881.
  36. ↑ F. Julia, T. Petrella, M. Beylot-Barry, M. Bagot, D. Lipsker, L. Machet, P. Joly, O. Dereure, M. Wetterwald, M. d’Incan, F. Grange, J. Cornillon, G. Tertian, E. Maubec, P. Saiag, S. Barete, I. Templier, F. Aubin & S. Dalle (2013). “Blastic plasmacytoid dendritic cell neoplasm: clinical features in 90 patients”. The British journal of dermatology. 169 (3): 579–586. doi:10.1111/bjd.12412. PMID 23646868. Unknown parameter |month= ignored (help)
  37. ↑ Livio Pagano, Caterina Giovanna Valentini, Alessandro Pulsoni, Simona Fisogni, Paola Carluccio, Francesco Mannelli, Monia Lunghi, Gianmatteo Pica, Francesco Onida, Chiara Cattaneo, Pier Paolo Piccaluga, Eros Di Bona, Elisabetta Todisco, Pellegrino Musto, Antonio Spadea, Alfonso D’Arco, Stefano Pileri, Giuseppe Leone, Sergio Amadori & Fabio Facchetti (2013). “Blastic plasmacytoid dendritic cell neoplasm with leukemic presentation: an Italian multicenter study”. Haematologica. 98 (2): 239–246. doi:10.3324/haematol.2012.072645. PMID 23065521. Unknown parameter |month= ignored (help)
  38. ↑ Joseph D. Khoury (2018). “Blastic Plasmacytoid Dendritic Cell Neoplasm”. Current hematologic malignancy reports. 13 (6): 477–483. doi:10.1007/s11899-018-0489-z. PMID 30350260. Unknown parameter |month= ignored (help)
  39. ↑ Shinichiro Sukegawa, Mamiko Sakata-Yanagimoto, Ryota Matsuoka, Haruka Momose, Yusuke Kiyoki, Masayuki Noguchi, Naoya Nakamura, Rei Watanabe, Manabu Fujimoto, Yasuhisa Yokoyama, Hidekazu Nishikii, Takayasu Kato, Manabu Kusakabe, Naoki Kurita, Naoshi Obara, Yuichi Hasegawa & Shigeru Chiba (2018). “[Blastic plasmacytoid dendritic cell neoplasm accompanied by chronic myelomonocytic leukemia successfully treated with azacitidine]”. [[[Rinsho ketsueki] The Japanese journal of clinical hematology]]. 59 (12): 2567–2573. doi:10.11406/rinketsu.59.2567. PMID 30626790.
  40. ↑ Patnaik MM, Tefferi A (June 2016). “Chronic myelomonocytic leukemia: 2016 update on diagnosis, risk stratification, and management”. Am. J. Hematol. 91 (6): 631–42. doi:10.1002/ajh.24396. PMID 27185207.
  41. ↑ Parikh SA, Tefferi A (June 2012). “Chronic myelomonocytic leukemia: 2012 update on diagnosis, risk stratification, and management”. Am. J. Hematol. 87 (6): 610–9. doi:10.1002/ajh.23203. PMID 22615103.
  42. ↑ Benton CB, Nazha A, Pemmaraju N, Garcia-Manero G (August 2015). “Chronic myelomonocytic leukemia: Forefront of the field in 2015”. Crit. Rev. Oncol. Hematol. 95 (2): 222–42. doi:10.1016/j.critrevonc.2015.03.002. PMC 4859155. PMID 25869097.
  43. ↑ Dao KH, Tyner JW (2015). “What’s different about atypical CML and chronic neutrophilic leukemia?”. Hematology Am Soc Hematol Educ Program. 2015: 264–71. doi:10.1182/asheducation-2015.1.264. PMC 5266507. PMID 26637732.
  44. ↑ Muramatsu H, Makishima H, Maciejewski JP (February 2012). “Chronic myelomonocytic leukemia and atypical chronic myeloid leukemia: novel pathogenetic lesions”. Semin. Oncol. 39 (1): 67–73. doi:10.1053/j.seminoncol.2011.11.004. PMC 3523950. PMID 22289493.
  45. ↑ Aricò M, Biondi A, Pui CH (July 1997). “Juvenile myelomonocytic leukemia”. Blood. 90 (2): 479–88. PMID 9226148.
  46. ↑ Hasle H (March 1994). “Myelodysplastic syndromes in childhood–classification, epidemiology, and treatment”. Leuk. Lymphoma. 13 (1–2): 11–26. doi:10.3109/10428199409051647. PMID 8025513.
  47. ↑ Patnaik MM, Tefferi A (March 2017). “Refractory anemia with ring sideroblasts (RARS) and RARS with thrombocytosis (RARS-T): 2017 update on diagnosis, risk-stratification, and management”. Am. J. Hematol. 92 (3): 297–310. doi:10.1002/ajh.24637. PMID 28188970.
  48. ↑ Alshaban A, Padilla O, Philipovskiy A, Corral J, McAlice M, Gaur S (2018). “Lenalidomide induced durable remission in a patient with MDS/MPN-with ring sideroblasts and thrombocytosis with associated 5q- syndrome”. Leuk Res Rep. 10: 37–40. doi:10.1016/j.lrr.2018.08.001. PMID 30186759.
  49. ↑ Bouchla A, Papageorgiou SG, Tsakiraki Z, Glezou E, Pavlidis G, Stavroulaki G, Bazani E, Foukas P, Pappa V (2018). “Plasmablastic Lymphoma in an Immunocompetent Patient with MDS/MPN with Ring Sideroblasts and Thrombocytosis-A Case Report”. Case Rep Hematol. 2018: 2525070. doi:10.1155/2018/2525070. PMC 6247723. PMID 30524760.
  50. ↑ You MJ, Medeiros LJ, Hsi ED (September 2015). “T-lymphoblastic leukemia/lymphoma”. Am. J. Clin. Pathol. 144 (3): 411–22. doi:10.1309/AJCPMF03LVSBLHPJ. PMID 26276771.
  51. ↑ Patel KJ, Latif SU, de Calaca WM (March 2009). “An unusual presentation of precursor T cell lymphoblastic leukemia/lymphoma with cholestatic jaundice: case report”. J Hematol Oncol. 2: 12. doi:10.1186/1756-8722-2-12. PMC 2663564. PMID 19284608.
  52. ↑ Elreda L, Sandhu M, Sun X, Bekele W, Cohen AJ, Shah M (2014). “T-cell lymphoblastic leukemia/lymphoma: relapse 16 years after first remission”. Case Rep Hematol. 2014: 359158. doi:10.1155/2014/359158. PMC 4005062. PMID 24822133.
  53. ↑ Sedick Q, Alotaibi S, Alshieban S, Naheet KB, Elyamany G (2017). “Natural Killer Cell Lymphoblastic Leukaemia/Lymphoma: Case Report and Review of the Recent Literature”. Case Rep Oncol. 10 (2): 588–595. doi:10.1159/000477843. PMID 28868017.
  54. ↑ Jain N, Lamb AV, O’Brien S, Ravandi F, Konopleva M, Jabbour E, Zuo Z, Jorgensen J, Lin P, Pierce S, Thomas D, Rytting M, Borthakur G, Kadia T, Cortes J, Kantarjian HM, Khoury JD (April 2016). “Early T-cell precursor acute lymphoblastic leukemia/lymphoma (ETP-ALL/LBL) in adolescents and adults: a high-risk subtype”. Blood. 127 (15): 1863–9. doi:10.1182/blood-2015-08-661702. PMC 4915808. PMID 26747249.
  55. ↑ Haydu JE, Ferrando AA (July 2013). “Early T-cell precursor acute lymphoblastic leukaemia”. Curr. Opin. Hematol. 20 (4): 369–73. doi:10.1097/MOH.0b013e3283623c61. PMC 3886681. PMID 23695450.
  56. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).
  57. ↑ Tefferi A, Gangat N, Loscocco GG, Guglielmelli P, Szuber N, Pardanani A, Orazi A, Barbui T, Vannucchi AM (February 2025). “Essential Thrombocythemia: A Review”. JAMA. 333 (8): 701–714. doi:10.1001/jama.2024.25349. PMID 39869325 Check |pmid= value (help).


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Natural History, Complications and Prognosis

Natural History, Complications and Prognosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Overview

If left untreated, patients with essential thrombocytosis may progress to develop symptoms like headache, dizziness, vision disturbances, chest pain, intense burning pain in hands and/or feet (erythromelalgia), numbness and tingling of hands and feet, and priapism (persistent and painful erection of the penis) depending on the vessel occluded with the thrombus. Common complications of essential thrombocytosis include thrombotic events (DVT, cerebrovascular accidents,etc), bleeding (bruises, gum bleeds, epistaxis, etc), acute leukemia, and myelofibrosis.[1][2] Prognosis is generally good, and the survival rate of patients is usually normal with regular medical supervision. However, the patient may rarely experience a leukemic conversion or develop myelofibrosis.

Natural history

  • The majority of patients with essential thrombocytosis remain asymptomatic for a long time and are diagnosed on routine blood tests or when tested for other conditions. Although some patients with very high counts may present with severe hemorrhagic or thombotic events, needing treatment.
  • The symptoms arise from complications of essential thrombocytosis and may include but are not limited to headache, dizziness, vision disturbances, chest pain, intense burning pain in hands and/or feet (erythromelalgia), numbness and tingling of hands and feet and priapism (persistent and painful erection of the penis).[1][3][4]
  • In predisposed individuals, gastrointestinal bleeding may sometimes worsen with aspirin where it is used to relieve symptoms of mild essential thrombocytosis. Hence it is contraindicated in these patients.[5]
  • Without treatment, patients with very high platelet counts will develop serious complications from vascular occlusion and/or bleeding.
  • Rarely some cases progress to fatal leukemia or may develop myelofibrosis.

Complications

Prognosis

  • Essential thrombocytosis is associated with a good prognosis if medically supervised on a regular basis.
  • Pregnancy in patients with essential thrombocytosis is associated with a two to three fold increase in risk for spontaneous micarriage and need special care.[8]

References

  1. ↑ 1.0 1.1 1.2 Frewin, R (October 2012). “Headache in essential thrombocythaemia” (PDF). International Journal of Clinical Practice. 66 (10): 976–83. doi:10.1111/j.1742-1241.2012.02986.x. PMC 3469735. PMID 22889110. Unknown parameter |coauthors= ignored (help)
  2. ↑ Tefferi, A (March 2011). “Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management”. American Journal of Hematology. 86 (3): 292–301. doi:10.1002/ajh.21946. PMID 21351120.
  3. ↑ Frewin, R (October 2012). “Headache in essential thrombocythaemia” (PDF). International Journal of Clinical Practice. 66 (10): 976–83. doi:10.1111/j.1742-1241.2012.02986.x. PMC 3469735. PMID 22889110. Unknown parameter |coauthors= ignored (help)
  4. ↑ Tefferi, A (March 2011). “Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management”. American Journal of Hematology. 86 (3): 292–301. doi:10.1002/ajh.21946. PMID 21351120.
  5. ↑ Brière JB (2007). “Essential thrombocythemia”. Orphanet J Rare Dis. 2: 3. doi:10.1186/1750-1172-2-3. PMC 1781427. PMID 17210076.
  6. ↑ Frewin, R (October 2012). “Headache in essential thrombocythaemia” (PDF). International Journal of Clinical Practice. 66 (10): 976–83. doi:10.1111/j.1742-1241.2012.02986.x. PMC 3469735. PMID 22889110. Unknown parameter |coauthors= ignored (help)
  7. ↑ Tefferi, A (March 2011). “Annual Clinical Updates in Hematological Malignancies: a continuing medical education series: polycythemia vera and essential thrombocythemia: 2011 update on diagnosis, risk-stratification, and management”. American Journal of Hematology. 86 (3): 292–301. doi:10.1002/ajh.21946. PMID 21351120.
  8. ↑ Essential thrombocythemia. Orphanet journal of rare diseases. http://www.ojrd.com/content/2/1/3 Accessed on November 11, 2015.


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