Essential Thrombocytosis

Pathology

Pathology of persistent thrombocytosis (>450 x 10⁹/l) that is not reactive or attributable to another myeloproliferative neoplasm or myelodysplasia must be considered.

Aetiology

The aetiology of persistent thrombocytosis is unknown, though around 50% of cases have been seen to possess a JAK-2 mutation. This is not associated with radiation, drugs, or chemicals.

Symptoms

• Often asymptomatic
• Thrombosis
• Headache
• Light-headedness
• Haemorrhage

Signs

• Erythromelalgia (burning sensation and erythema in hands and feet caused by microthrombi)
• Splenomegaly

Investigations

• Bloods: FBC shows platelets persistently >450 with all other readings being normal. JAK-2 mutation is present in 50% of cases.
• Blood Film: giant platelets and platelet clumps.

Treatment

• Conservative: Lifestyle changes to reduce clot risk, treat thrombotic risks
• Medical: Busulfan, hydroxyurea, or interferon-alpha

Complications

Complications to be aware of include the risk of transformation to myelofibrosis or acute myeloid leukaemia (AML), although this is less likely than in polycythaemia vera (PV).

Prognosis

The prognosis for individuals with persistent thrombocytosis is near normal life expectancy.