Primary thrombocythemia

Primary Thrombocythemia Primary thrombocythemia, also known as essential thrombocythemia (ET), is a rare chronic blood disorder characterized by the overproduction of platelets by the bone marrow. This condition is classified as a myeloproliferative neoplasm (MPN), which is a group of diseases that cause an abnormal increase in blood cells.

Pathophysiology

The pathophysiology of primary thrombocythemia involves the clonal proliferation of hematopoietic stem cells, leading to an increased production of platelets. This is often due to mutations in genes such as JAK2, CALR, or MPL. These mutations lead to constitutive activation of signaling pathways that promote cell proliferation and survival.

Symptoms

Many individuals with primary thrombocythemia are asymptomatic and are diagnosed incidentally through routine blood tests. When symptoms do occur, they may include:

• Headaches
• Dizziness or lightheadedness
• Visual disturbances
• Burning or tingling sensations in the hands and feet (erythromelalgia)
• Increased risk of thrombosis (blood clots)
• Bleeding complications, such as nosebleeds or easy bruising

Diagnosis

The diagnosis of primary thrombocythemia is based on:

• Complete blood count (CBC) showing elevated platelet count
• Bone marrow biopsy revealing increased megakaryocytes
• Genetic testing for mutations in JAK2, CALR, or MPL
• Exclusion of other causes of thrombocytosis, such as reactive thrombocytosis or other myeloproliferative neoplasms

Treatment

Treatment for primary thrombocythemia aims to reduce the risk of thrombotic and hemorrhagic complications. Options include:

• Low-dose aspirin to reduce the risk of blood clots
• Cytoreductive therapy with medications such as hydroxyurea or anagrelide to lower platelet counts
• Interferon-alpha, particularly in younger patients or during pregnancy
• Regular monitoring and follow-up with a hematologist

Prognosis

The prognosis for individuals with primary thrombocythemia is generally favorable, with many patients maintaining a normal life expectancy. However, there is a risk of progression to myelofibrosis or acute myeloid leukemia in a small percentage of patients.

See Also

• Myeloproliferative neoplasm
• Thrombocytosis
• JAK2
• Tefferi, A., & Barbui, T. (2019). Essential thrombocythemia and polycythemia vera: 2020 update on diagnosis, risk-stratification and management. American Journal of Hematology, 94(1), 133-143.
• Arber, D. A., et al. (2016). The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia. Blood, 127(20), 2391-2405.

NIH genetic and rare disease info

• NIH info on Primary thrombocythemia

Primary thrombocythemia is a rare disease.