Treatment of essential thrombocythemia in childhood.

Essential thrombocythemia is a rare myeloproliferative disorder in childhood. For symptomatic patients with platelet counts greater than 1000 x 10(9)/L, cytoreductive treatment is recommended. The authors describe a 5-year-old boy with symptomatic essential thrombocythemia who was treated with anagrelide (Agrylin) for 23 months. He responded well but early on developed anemia. Because anagrelide is thought to specifically inhibit thrombopoesis, anemia is assumed to be a rather rare and late adverse effect. Its early occurence in this patient might indicate an increased vulnerability to anagrelide (Agrylin) in young children.