RESUMO
Objective To observe the efficacy of imatinib on the treatment of bcr-abl positive essential thrombocythemia (ET). Methods A case of bcr-abl positive ET resistant to hydroxyurea (HU) treating with imatinib (200～400 mg/d) was reported and related literatures were reviewed. Results A case of bcr-abl positive ET was initially treated with 1.5～2.0 g/d HU, the platelet count decreased to 562x109/L after 4 weeks; however, the platelet count increased to (1020～1330)×109/L treating with same dose of HU 16 months later. With the elevation of HU to 3.0 g/d, platelet count was still high(1290～1780)x109/L companied with the very low white blood cell count(0.3～0.9)×109/L. While treating with imatinib (400 mg/d) for 1 month,the platelet count decreased to 390×109/L and white blood cell count was 0.5×109/L; Furthermore, treating with 200×300 mg/d of imatinib, the platelet and white blood cell count recovered in normal after 1 month,and bcr-abl fusion gene negative 2 months later. Conclusion Imatinib may be the effective targeting drug for the bcr-abl positive ET, and the bcr-abl positive ET is sensitive to low dose imatinib.