Platelet apheresis for extreme thrombocytosis in an 11-year-old girl with CML.

This report describes the dramatic reduction in the platelet count and ablation of symptoms by consecutive platelet apheresis in a young girl with CML who presented with an extremely high platelet count of 10,320 x 10(9)/l. Extreme thrombocytosis, although quite rare, can be symptomatic and life-threatening in paediatric patients and should be considered an emergency. The mechanical removal of platelets by apheresis is effective therapy and should begin as soon as possible.