Two cases of pediatric essential thrombocythemia managed effectively with hydroxyurea.

Thrombocytosis is common in infancy and childhood. Essential thrombocythemia (ET), a myeloproliferative disorder, is a much less common cause of thrombocytosis in childhood. We report two cases of essential thrombocythemia in 5- and 10-year-old children, who presented with platelet counts of more than 1,000,000/mm(3). Treatment is not recommended for ET in an asymptomatic patient in the absence of bleeding or thrombosis and a platelet count <1,500,000/mm(3). Our first case had platelets >1,500,000/mm(3), and a second child was symptomatic with recurrent headache. Both responded well to therapy with hydroxyurea (dose 15-30 mg/kg/day) and tolerated it well.