Essential thrombocytosis
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
| Essential thrombocytosis Classification and external resources | |
| ICD-10 | D75.2, D47.3 |
|---|---|
| ICD-9 | 289.9 |
| ICD-O: | 9962/3 |
| OMIM | 187950 |
| DiseasesDB | 4522 |
| MedlinePlus | 000543 |
| eMedicine | med/2266 |
| MeSH | D013920 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Essential thrombocytosis (ET, also known as essential thrombocythemia) is a rare chronic blood disorder characterized by the overproduction of platelets by megakaryocytes in the bone marrow in the absence of an alternative cause. In some cases this disorder may be progressive, and rarely may evolve into acute myeloid leukemia or myelofibrosis. It is one of four myeloproliferative disorders.
Epidemiology
Essential thrombocytosis is diagnosed at a rate of about 2 to 3 per 100,000 individuals annually.[1][1] The disease usually affects middle aged to elderly individuals, with an average age at diagnosis of 50-60 years, although it can affect children and young adults as well.[1]
Pathophysiology
The pathologic basis for this disease is unknown. However, essential thrombosis resembles polycythemia vera in that cells of the megakaryocytic series are more sensitive to growth factors. Platelets derived from the abnormal megakaryocytes do not function properly, which contributes to the clinical features of bleeding and thrombosis.
In 2005, a mutation in the JAK2 kinase (V617F) was found by multiple research groups [1][1] [1] to be associated with essential thrombocytosis in around 30% of cases. JAK2 is a member of the Janus kinase family. This mutation may be helpful in making a diagnosis or as a target for future therapy.
Clinical features
The major symptoms are bleeding and thrombosis. Other symptoms include epistaxis (nosebleeds) and bleeding from gums and gastrointestinal tract. One characteristic symptom is throbbing and burning of the hands and feet due to the occlusion of small arterioles by platelets (erythromelalgia). An enlarged spleen (splenomegaly) may be found on examination.
Diagnostic criteria
The diagnosis of essential thrombocytosis requires the presence of a persistent thrombocytosis of greater than 600 x109/L in the absence of an alternative cause.
The following revised diagnostic criteria for essential thrombocytosis were proposed in 2005 [1]. The diagnosis requires the presence of both A criteria together with B3 to B6, or of criterion A1 together with B1 to B6.
- A1. Platelet count > 600 x 109/L for at least 2 months
- A2. Acquired V617F JAK2 mutation present
- B1. No cause for a reactive thrombocytosis
- normal inflammatory indices
- B2. No evidence of iron deficiency
- stainable iron in the bone marrow or normal red cell mean corpuscular volume
- B3. No evidence of polycythemia vera
- hematocrit < midpoint of normal range or normal red cell mass in presence of normal iron stores
- B4. No evidence of chronic myeloid leukemia
But the Philadelphia chromosome may be present in up to 10% of cases. Patients withe the Philadelphia chromosome have a potential for the development of acute leukemia, especially acute lymphocytic leukemia.
- B5. No evidence of myelofibrosis
- no collagen fibrosis and ≤ grade 2 reticulin fibrosis (using 0–4 scale)
- B6. No evidence of a myelodysplastic syndrome
- no significant dysplasia
- no cytogenetic abnormalities suggestive of myelodysplasia
Treatment
Not all patients will require treatment at presentation. In those who are at increased risk of thrombosis or bleeding (older age, prior history of bleeding or thrombosis, or very high platelet count), reduction of the platelet count to the normal range can be achieved using hydroxyurea (also known as hydroxycarbamide), interferon-α or anagrelide. Low-dose aspirin is widely used to reduce the risk of thrombosis, but there may be an increased risk of bleeding if aspirin is initiated whilst the platelet count is very high.
The PT1 study [1] compared hydroxyurea in combination with aspirin to anagrelide in combination with Aspirin as initial therapy for essential thrombocytosis. Hydroxyurea was superior, with lower risk of arterial thrombosis, lower risk of severe bleeding and lower risk of transformation to myelofibrosis (although the rate of venous thrombosis was higher with hydroxycarbamide than with anagrelide).
In rare cases where patients have life-threatening complications, the platelet count can be reduced rapidly using platelet apheresis (a procedure that removes platelets from the blood directly).
Prognosis
Essential thrombocytosis is a slowly progressive disorder with long asymptomatic periods punctuated by thrombotic or hemorrhagic events.
Special care related to pregnancy
Hydroxyrea and anagrelide are counter-indicated during pregnancy and nursing. There is current debate as to the safety of interferon during pregnancy and nursing. Essential thrombocytosis can be linked with increased risk of spontaeous abortion or miscarriage in the first trimester of pregnancy. Throughout pregnancy, close monitoring of the mother for thrombosis and placenta is recommended to ensure blood clots are caught. Post partum, often daily injections of low dose low molecular weight heparin (e.g. enoxaparin) are prescribed for several weeks as this is a period where the mother is at higher risk of developing a blood clot.
References
External links
- Cancerbackup Essential Thrombocytosis page
- CMPD Education Foundation
- MPD Foundation and Research Alliance - Register for a free newsletter
- Overview of Agrylin, the tradename for anagrelide hydrochloride
Pathology: hematology, myeloid hematologic disease (primarily D50-D77, 280-289) | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| RBCs/ hemoglobinopathy |
| ||||||||||||||||||||
| Coagulation/platelets/ coagulopathy/ bleeding diathesis |
| ||||||||||||||||||||
| Monocytes/ macrophages |
| ||||||||||||||||||||
| Granulocytes |
| ||||||||||||||||||||
| See also hematological malignancy and immune disorders | |||||||||||||||||||||
WikiDoc Research Resources for Essential thrombocytosis | |
|---|---|
| Articles on Essential thrombocytosis | Most recent articles on Essential thrombocytosis • Most cited articles on Essential thrombocytosis • Review articles on Essential thrombocytosis • Articles on Essential thrombocytosis in N Eng J Med, Lancet, BMJ |
| Media (Slides, Video, Images, MP3) on Essential thrombocytosis | Powerpoint slides on Essential thrombocytosis • Images of Essential thrombocytosis • Photos of Essential thrombocytosis • Podcasts & MP3s on Essential thrombocytosis • Videos on Essential thrombocytosis |
| Evidence Based Medicine Regarding Essential thrombocytosis | Cochrane Collaboration on Essential thrombocytosis • Bandolier on Essential thrombocytosis • TRIP on Essential thrombocytosis |
| Cost Effectiveness of Essential thrombocytosis | Cost Effectiveness of Essential thrombocytosis |
| Clinical Trials Involving Essential thrombocytosis | Ongoing Trials on Essential thrombocytosis at Clinical Trials.gov • Trial results on Essential thrombocytosis • Clinical Trials on Essential thrombocytosis at Google |
| Guidelines / Policies / Government Resources (FDA/CDC) Regarding Essential thrombocytosis | US National Guidelines Clearinghouse on Essential thrombocytosis • NICE Guidance on Essential thrombocytosis • NHS PRODIGY Guidance • FDA on Essential thrombocytosis • CDC on Essential thrombocytosis |
| Textbook Information on Essential thrombocytosis | Books and Textbook Information on Essential thrombocytosis |
| Pharmacology Resources on Essential thrombocytosis | Dosing of Essential thrombocytosis • Drug interactions with Essential thrombocytosis • Side effects of Essential thrombocytosis • Allergic reactions to Essential thrombocytosis • Overdose information on Essential thrombocytosis • Carcinogenicity information on Essential thrombocytosis • Essential thrombocytosis in pregnancy • Pharmacokinetics of Essential thrombocytosis • |
| Genetics, Pharmacogenomics, and Proteinomics of Essential thrombocytosis | Genetics of Essential thrombocytosis • Pharmacogenomics of Essential thrombocytosis • Proteomics of Essential thrombocytosis |
| Newstories on Essential thrombocytosis | Essential thrombocytosis in the news • Be alerted to news on Essential thrombocytosis • News trends on Essential thrombocytosis |
| Commentary on Essential thrombocytosis | Blogs on Essential thrombocytosis |
| Patient Resources on Essential thrombocytosis | Patient resources on Essential thrombocytosis • Discussion groups on Essential thrombocytosis • Patient Handouts on Essential thrombocytosis • Directions to Hospitals Treating Essential thrombocytosis • Risk calculators and risk factors for Essential thrombocytosis |
| Healthcare Provider Resources on Essential thrombocytosis | Symptoms of Essential thrombocytosis • Causes & Risk Factors for Essential thrombocytosis • Diagnostic studies for Essential thrombocytosis • Treatment of Essential thrombocytosis |
| Continuing Medical Education (CME) Programs on Essential thrombocytosis | CME Programs on Essential thrombocytosis |
| International Resources on Essential thrombocytosis | Essential thrombocytosis en Espanol • Essential thrombocytosis en Francais |
| Business Resources on Essential thrombocytosis | Essential thrombocytosis in the Marketplace • Patents on Essential thrombocytosis |
| Informatics Resources on Essential thrombocytosis | List of terms related to Essential thrombocytosis |
de:Essentielle Thrombozythämie fr:Thrombocytémie essentielle
| ||||
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
