Essential thrombocytosis (primary thrombocythaemia) is a myeloproliferative disorder associated with an increase in number and size of circulating platelets.
Half of all patients are asymptomatic, but clinical presentations include thrombosis and bleeding. There are no pathognomonic features and it is a diagnosis of exclusion.
Four risk categories exist to group patients with essential thrombocytosis: very low-risk, low-risk, intermediate-risk, and high-risk.
Treatment approach should be individualised and may include lifestyle modification and observation, cytoreductive therapy, antiplatelet and anticoagulant therapy.
Hydroxycarbamide is the preferred cytoreductive agent in most people with the disease. Interferon, busulfan, and anagrelide are alternative treatments.
The life expectancy for people with essential thrombocytosis is usually similar to that for people without the disease. Patients need FBCs on a regular follow-up basis.
Essential thrombocytosis is also known as primary thrombocythaemia. It is a chronic myeloproliferative disorder associated with sustained dysregulated megakaryocyte proliferation, increasing the number of circulating platelets. It is associated with thrombosis and bleeding.
History and exam
Key diagnostic factors
- arterial and venous thrombosis
- livedo reticularis
Other diagnostic factors
- age 50 to 70 years
- female sex
- no symptoms
- dizziness, lightheadedness, and paraesthesias
- syncope and seizures
- transient visual disturbances
- Unknown risk factors
- Genetic mutations (e.g., JAK2, CALR, or MPL)
1st investigations to order
- FBC with peripheral smear
- iron panel
Investigations to consider
- bone marrow biopsy and histopathology
- Janus kinase 2 (JAK2) mutation testing of peripheral blood
- myeloproliferative leukaemia virus oncogene (MPL) mutation testing of peripheral blood
- calreticulin (CALR) mutation testing of peripheral blood
- BCR-ABL fluorescent in situ hybridisation (FISH) of bone marrow
thrombosis or bleeding
non-pregnant: very low-, low-, or intermediate-risk
non-pregnant: high risk
pregnant: very low- or low-risk
- Secondary (reactive) thrombocytosis
- Spurious thrombocytosis
- Familial essential thrombocythaemia
- Unmet clinical needs in the management of CALR-mutated essential thrombocythaemia: a consensus-based proposal from the European LeukemiaNet
- Essential thrombocythemia treatment algorithm 2018
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