ESSENTIAL THROMBACYTHEMIA WITH BCR ABL REARRANGEMENT/

Essential thrombocythemia (ET) was diagnosed clinically in three patie nts. Karyotypic analysis and reverse transcription polymerase chain re action for the bcr-abl chimeric transcript showed that two were Philad elphia chromosome (Ph) positive, bcr-abl positive, whereas the third w as Ph negative, bcr-abl positive. The first patient received an alloge neic bone marrow transplantation but relapsed as localized blastic tra nsformation, thus behaving similarly to chronic myeloid leukemia (CML) . However, the other patients showed clinical courses more in keeping with ET. Essential thrombocythemia with BCR rearrangements may resembl e CML but there are clinical differences. These may be due to genetic changes in addition to the BCR rearrangement.